1
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Slewinski TL. Plant development: Laying the foundation for high-performance photosynthesis. Curr Biol 2024; 34:R326-R328. [PMID: 38653202 DOI: 10.1016/j.cub.2024.03.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Abstract
A new study shows that TOO MANY LATERALS/WIP6 acts as a key regulator of vein specification and development across C3 and C4 photosynthetic grasses.
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Affiliation(s)
- Thomas L Slewinski
- Lead of Crop Efficiency and Disease Discovery, Bayer Crop Science, Biotechnology Division, 700 Chesterfield Parkway West, Chesterfield, MO 63017, USA; Adjunct Faculty, Department of Plant Science, University of Missouri, Columbia, MO 65201, USA. thomas.slewinski,@,bayer.com
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2
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Mahapatra K, Mukherjee A, Suyal S, Dar MA, Bhagavatula L, Datta S. Regulation of chloroplast biogenesis, development, and signaling by endogenous and exogenous cues. Physiol Mol Biol Plants 2024; 30:167-183. [PMID: 38623168 PMCID: PMC11016055 DOI: 10.1007/s12298-024-01427-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 02/07/2024] [Accepted: 02/27/2024] [Indexed: 04/17/2024]
Abstract
Chloroplasts are one of the defining features in most plants, primarily known for their unique property to carry out photosynthesis. Besides this, chloroplasts are also associated with hormone and metabolite productions. For this, biogenesis and development of chloroplast are required to be synchronized with the seedling growth to corroborate the maximum rate of photosynthesis following the emergence of seedlings. Chloroplast biogenesis and development are dependent on the signaling to and from the chloroplast, which are in turn regulated by several endogenous and exogenous cues. Light and hormones play a crucial role in chloroplast maturation and development. Chloroplast signaling involves a coordinated two-way connection between the chloroplast and nucleus, termed retrograde and anterograde signaling, respectively. Anterograde and retrograde signaling are involved in regulation at the transcriptional level and downstream modifications and are modulated by several metabolic and external cues. The communication between chloroplast and nucleus is essential for plants to develop strategies to cope with various stresses including high light or high heat. In this review, we have summarized several aspects of chloroplast development and its regulation through the interplay of various external and internal factors. We have also discussed the involvement of chloroplasts as sensors of various external environment stress factors including high light and temperature, and communicate via a series of retrograde signals to the nucleus, thus playing an essential role in plants' abiotic stress response.
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Affiliation(s)
- Kalyan Mahapatra
- Plant Cell and Developmental Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research (IISER), Bhopal, Madhya Pradesh 462066 India
| | - Arpan Mukherjee
- Plant Cell and Developmental Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research (IISER), Bhopal, Madhya Pradesh 462066 India
| | - Shikha Suyal
- Plant Cell and Developmental Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research (IISER), Bhopal, Madhya Pradesh 462066 India
| | - Mansoor Ali Dar
- Plant Cell and Developmental Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research (IISER), Bhopal, Madhya Pradesh 462066 India
| | | | - Sourav Datta
- Plant Cell and Developmental Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research (IISER), Bhopal, Madhya Pradesh 462066 India
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3
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Li X, Li J, Wei S, Gao Y, Pei H, Geng R, Lu Z, Wang P, Zhou W. Maize GOLDEN2-LIKE proteins enhance drought tolerance in rice by promoting stomatal closure. Plant Physiol 2024; 194:774-786. [PMID: 37850886 PMCID: PMC10828204 DOI: 10.1093/plphys/kiad561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Revised: 09/26/2023] [Accepted: 09/29/2023] [Indexed: 10/19/2023]
Abstract
Drought has become one of the most severe abiotic stresses experienced in agricultural production across the world. Plants respond to water deficit via stomatal movements in the leaves, which are mainly regulated by abscisic acid (ABA). A previous study from our lab showed that constitutive expression of maize (Zea mays L.) GOLDEN2-LIKE (GLK) transcription factors in rice (Oryza sativa L.) can improve stomatal conductance and plant photosynthetic capacity under field conditions. In the present study, we uncovered a function of ZmGLK regulation of stomatal movement in rice during drought stress. We found that elevated drought tolerance in rice plants overexpressing ZmGLK1 or GOLDEN2 (ZmG2) was conferred by rapid ABA-mediated stomatal closure. Comparative analysis of RNA-sequencing (RNA-seq) data from the rice leaves and DNA affinity purification sequencing (DAP-seq) results obtained in vitro revealed that ZmGLKs played roles in regulating ABA-related and stress-responsive pathways. Four upregulated genes closely functioning in abiotic stress tolerance with strong binding peaks in the DAP-seq data were identified as putative target genes of ZmGLK1 and ZmG2 in rice. These results demonstrated that maize GLKs play an important role in regulating stomatal movements to coordinate photosynthesis and stress tolerance. This trait is a valuable target for breeding drought-tolerant crop plants without compromising photosynthetic capacity.
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Affiliation(s)
- Xia Li
- Institute of Crop Sciences, Chinese Academy of Agricultural
Sciences, Beijing 100081, China
| | - Jing Li
- Institute of Crop Sciences, Chinese Academy of Agricultural
Sciences, Beijing 100081, China
| | - Shaobo Wei
- Institute of Crop Sciences, Chinese Academy of Agricultural
Sciences, Beijing 100081, China
| | - Yuan Gao
- Institute of Crop Sciences, Chinese Academy of Agricultural
Sciences, Beijing 100081, China
| | - Hongcui Pei
- Institute of Crop Sciences, Chinese Academy of Agricultural
Sciences, Beijing 100081, China
| | - Rudan Geng
- Institute of Crop Sciences, Chinese Academy of Agricultural
Sciences, Beijing 100081, China
| | - Zefu Lu
- Institute of Crop Sciences, Chinese Academy of Agricultural
Sciences, Beijing 100081, China
| | - Peng Wang
- CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant
Physiology and Ecology, Chinese Academy of Sciences, Shanghai
200032, China
| | - Wenbin Zhou
- Institute of Crop Sciences, Chinese Academy of Agricultural
Sciences, Beijing 100081, China
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4
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Liu Z, Cheng J. C 4 rice engineering, beyond installing a C 4 cycle. Plant Physiol Biochem 2024; 206:108256. [PMID: 38091938 DOI: 10.1016/j.plaphy.2023.108256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 11/28/2023] [Accepted: 11/30/2023] [Indexed: 02/15/2024]
Abstract
C4 photosynthesis in higher plants is carried out by two distinct cell types: mesophyll cells and bundle sheath cells, as a result highly concentrated carbon dioxide is released surrounding RuBisCo in chloroplasts of bundle sheath cells and the photosynthetic efficiency is significantly higher than that of C3 plants. The evolution of the dual-cell C4 cycle involved complex modifications to leaf anatomy and cell ultra-structures. These include an increase in leaf venation, the formation of Kranz anatomy, changes in chloroplast morphology in bundle sheath cells, and increases in the density of plasmodesmata at interfaces between the bundle sheath and mesophyll cells. It is predicted that cereals will be in severe worldwide shortage at the mid-term of this century. Rice is a staple food that feeds more than half of the world's population. If rice can be engineered to perform C4 photosynthesis, it is estimated that rice yield will be increased by at least 50% due to enhanced photosynthesis. Thus, the Second Green Revolution has been launched on this principle by genetically installing C4 photosynthesis into C3 crops. The studies on molecular mechanisms underlying the changes in leaf morphoanatomy involved in C4 photosynthesis have made great progress in recent years. As there are plenty of reviews discussing the installment of the C4 cycle, we focus on the current progress and challenges posed to the research regarding leaf anatomy and cell ultra-structure modifications made towards the development of C4 rice.
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Affiliation(s)
- Zheng Liu
- State Key Laboratory of North China Crop Improvement and Regulation, College of Agronomy, Hebei Agricultural University, Baoding, 071001, China.
| | - Jinjin Cheng
- College of Agronomy, Shanxi Agricultural University, Jinzhong, 030801, China
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Schreier TB, Müller KH, Eicke S, Faulkner C, Zeeman SC, Hibberd JM. Plasmodesmal connectivity in C 4 Gynandropsis gynandra is induced by light and dependent on photosynthesis. New Phytol 2024; 241:298-313. [PMID: 37882365 PMCID: PMC10952754 DOI: 10.1111/nph.19343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2022] [Accepted: 09/28/2023] [Indexed: 10/27/2023]
Abstract
In leaves of C4 plants, the reactions of photosynthesis become restricted between two compartments. Typically, this allows accumulation of C4 acids in mesophyll (M) cells and subsequent decarboxylation in the bundle sheath (BS). In C4 grasses, proliferation of plasmodesmata between these cell types is thought to increase cell-to-cell connectivity to allow efficient metabolite movement. However, it is not known whether C4 dicotyledons also show this enhanced plasmodesmal connectivity and so whether this is a general requirement for C4 photosynthesis is not clear. How M and BS cells in C4 leaves become highly connected is also not known. We investigated these questions using 3D- and 2D-electron microscopy on the C4 dicotyledon Gynandropsis gynandra as well as phylogenetically close C3 relatives. The M-BS interface of C4 G. gynandra showed higher plasmodesmal frequency compared with closely related C3 species. Formation of these plasmodesmata was induced by light. Pharmacological agents that perturbed photosynthesis reduced the number of plasmodesmata, but this inhibitory effect could be reversed by the provision of exogenous sucrose. We conclude that enhanced formation of plasmodesmata between M and BS cells is wired to the induction of photosynthesis in C4 G. gynandra.
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Affiliation(s)
- Tina B. Schreier
- Department of Plant SciencesUniversity of CambridgeDowning StreetCambridgeCB1 3EAUK
- Present address:
Department of BiologyUniversity of OxfordSouth Parks RoadOxfordOX1 3RBUK
| | - Karin H. Müller
- Cambridge Advanced Imaging Centre (CAIC)University of CambridgeDowning StreetCambridgeCB2 3DYUK
| | - Simona Eicke
- Institute of Molecular Plant BiologyETH ZurichZurichCH‐8092Switzerland
| | - Christine Faulkner
- Cell and Developmental BiologyJohn Innes CentreNorwich Research ParkNorwichNR4 7UHUK
| | - Samuel C. Zeeman
- Institute of Molecular Plant BiologyETH ZurichZurichCH‐8092Switzerland
| | - Julian M. Hibberd
- Department of Plant SciencesUniversity of CambridgeDowning StreetCambridgeCB1 3EAUK
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6
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DiMario RJ, Kophs AN, Apalla AJA, Schnable JN, Cousins AB. Multiple highly expressed phosphoenolpyruvate carboxylase genes have divergent enzyme kinetic properties in two C4 grasses. Ann Bot 2023; 132:413-428. [PMID: 37675505 PMCID: PMC10667006 DOI: 10.1093/aob/mcad116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Accepted: 09/06/2023] [Indexed: 09/08/2023]
Abstract
BACKGROUND AND AIMS Phosphoenolpyruvate (PEP) carboxylase (PEPC) catalyses the irreversible carboxylation of PEP with bicarbonate to produce oxaloacetate. This reaction powers the carbon-concentrating mechanism (CCM) in plants that perform C4 photosynthesis. This CCM is generally driven by a single PEPC gene product that is highly expressed in the cytosol of mesophyll cells. We found two C4 grasses, Panicum miliaceum and Echinochloa colona, that each have two highly expressed PEPC genes. We characterized the kinetic properties of the two most abundant PEPCs in E. colona and P. miliaceum to better understand how the enzyme's amino acid structure influences its function. METHODS Coding sequences of the two most abundant PEPC proteins in E. colona and P. miliaceum were synthesized by GenScript and were inserted into bacteria expression plasmids. Point mutations resulting in substitutions at conserved amino acid residues (e.g. N-terminal serine and residue 890) were created via site-directed PCR mutagenesis. The kinetic properties of semi-purified plant PEPCs from Escherichia coli were analysed using membrane-inlet mass spectrometry and a spectrophotometric enzyme-coupled reaction. KEY RESULTS The two most abundant P. miliaceum PEPCs (PmPPC1 and PmPPC2) have similar sequence identities (>95 %), and as a result had similar kinetic properties. The two most abundant E. colona PEPCs (EcPPC1 and EcPPC2) had identities of ~78 % and had significantly different kinetic properties. The PmPPCs and EcPPCs had different responses to allosteric inhibitors and activators, and substitutions at the conserved N-terminal serine and residue 890 resulted in significantly altered responses to allosteric regulators. CONCLUSIONS The two, significantly expressed C4Ppc genes in P. miliaceum were probably the result of genomes combining from two closely related C4Panicum species. We found natural variation in PEPC's sensitivity to allosteric inhibition that seems to bypass the conserved 890 residue, suggesting alternative evolutionary pathways for increased malate tolerance and other kinetic properties.
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Affiliation(s)
- Robert J DiMario
- School of Biological Sciences, Washington State University, Pullman, WA 99164, USA
| | - Ashley N Kophs
- School of Biological Sciences, Washington State University, Pullman, WA 99164, USA
| | - Anthony J A Apalla
- School of Biological Sciences, Washington State University, Pullman, WA 99164, USA
| | - James N Schnable
- Department of Agronomy and Horticulture, University of Nebraska, Lincoln, NE 68583, USA
| | - Asaph B Cousins
- School of Biological Sciences, Washington State University, Pullman, WA 99164, USA
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Wang X, Ma X, Yan G, Hua L, Liu H, Huang W, Liang Z, Chao Q, Hibberd JM, Jiao Y, Zhang M. Gene duplications facilitate C4-CAM compatibility in common purslane. Plant Physiol 2023; 193:2622-2639. [PMID: 37587696 PMCID: PMC10663116 DOI: 10.1093/plphys/kiad451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 07/14/2023] [Accepted: 07/19/2023] [Indexed: 08/18/2023]
Abstract
Common purslane (Portulaca oleracea) integrates both C4 and crassulacean acid metabolism (CAM) photosynthesis pathways and is a promising model plant to explore C4-CAM plasticity. Here, we report a high-quality chromosome-level genome of nicotinamide adenine dinucleotide (NAD)-malic enzyme (ME) subtype common purslane that provides evidence for 2 rounds of whole-genome duplication (WGD) with an ancient WGD (P-β) in the common ancestor to Portulacaceae and Cactaceae around 66.30 million years ago (Mya) and another (Po-α) specific to common purslane lineage around 7.74 Mya. A larger number of gene copies encoding key enzymes/transporters involved in C4 and CAM pathways were detected in common purslane than in related species. Phylogeny, conserved functional site, and collinearity analyses revealed that the Po-α WGD produced the phosphoenolpyruvate carboxylase-encoded gene copies used for photosynthesis in common purslane, while the P-β WGD event produced 2 ancestral genes of functionally differentiated (C4- and CAM-specific) beta carbonic anhydrases involved in the C4 + CAM pathways. Additionally, cis-element enrichment analysis in the promoters showed that CAM-specific genes have recruited both evening and midnight circadian elements as well as the Abscisic acid (ABA)-independent regulatory module mediated by ethylene-response factor cis-elements. Overall, this study provides insights into the origin and evolutionary process of C4 and CAM pathways in common purslane, as well as potential targets for engineering crops by integrating C4 or CAM metabolism.
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Affiliation(s)
- Xiaoliang Wang
- Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- State Key Laboratory of Plant Diversity and Specialty Crops, Beijing 100093, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- China National Botanical Garden, Beijing 100093, China
| | - Xuxu Ma
- Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- China National Botanical Garden, Beijing 100093, China
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Ge Yan
- Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- China National Botanical Garden, Beijing 100093, China
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Lei Hua
- Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, UK
| | - Han Liu
- Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- China National Botanical Garden, Beijing 100093, China
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Wei Huang
- National Maize Improvement Center, China Agricultural University, Beijing 100193, China
| | - Zhikai Liang
- Department of Plant and Microbial Biology, University of Minnesota, Saint Paul, MN 55108, USA
| | - Qing Chao
- Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- China National Botanical Garden, Beijing 100093, China
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Julian M Hibberd
- Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, UK
| | - Yuannian Jiao
- Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- State Key Laboratory of Plant Diversity and Specialty Crops, Beijing 100093, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- China National Botanical Garden, Beijing 100093, China
| | - Mei Zhang
- Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- China National Botanical Garden, Beijing 100093, China
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
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8
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Guerreiro R, Bonthala VS, Schlüter U, Hoang NV, Triesch S, Schranz ME, Weber APM, Stich B. A genomic panel for studying C3-C4 intermediate photosynthesis in the Brassiceae tribe. Plant Cell Environ 2023; 46:3611-3627. [PMID: 37431820 DOI: 10.1111/pce.14662] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 05/18/2023] [Accepted: 06/23/2023] [Indexed: 07/12/2023]
Abstract
Research on C4 and C3-C4 photosynthesis has attracted significant attention because the understanding of the genetic underpinnings of these traits will support the introduction of its characteristics into commercially relevant crop species. We used a panel of 19 taxa of 18 Brassiceae species with different photosynthesis characteristics (C3 and C3-C4) with the following objectives: (i) create draft genome assemblies and annotations, (ii) quantify orthology levels using synteny maps between all pairs of taxa, (iii) describe the phylogenetic relatedness across all the species, and (iv) track the evolution of C3-C4 intermediate photosynthesis in the Brassiceae tribe. Our results indicate that the draft de novo genome assemblies are of high quality and cover at least 90% of the gene space. Therewith we more than doubled the sampling depth of genomes of the Brassiceae tribe that comprises commercially important as well as biologically interesting species. The gene annotation generated high-quality gene models, and for most genes extensive upstream sequences are available for all taxa, yielding potential to explore variants in regulatory sequences. The genome-based phylogenetic tree of the Brassiceae contained two main clades and indicated that the C3-C4 intermediate photosynthesis has evolved five times independently. Furthermore, our study provides the first genomic support of the hypothesis that Diplotaxis muralis is a natural hybrid of D. tenuifolia and D. viminea. Altogether, the de novo genome assemblies and the annotations reported in this study are a valuable resource for research on the evolution of C3-C4 intermediate photosynthesis.
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Affiliation(s)
- Ricardo Guerreiro
- Institute of Quantitative Genetics and Genomics of Plants, Faculty of Mathematics and Natural Sciences, Heinrich Heine University, Düsseldorf, Germany
| | - Venkata Suresh Bonthala
- Institute of Quantitative Genetics and Genomics of Plants, Faculty of Mathematics and Natural Sciences, Heinrich Heine University, Düsseldorf, Germany
| | - Urte Schlüter
- Institute of Plant Biochemistry, Faculty of Mathematics and Natural Sciences, Heinrich Heine University, Düsseldorf, Germany
- Cluster of Excellence on Plant Sciences (CEPLAS), Düsseldorf, Germany
| | - Nam V Hoang
- Biosystematics Group, Department of Plant Sciences, Wageningen University, Wageningen, The Netherlands
| | - Sebastian Triesch
- Institute of Plant Biochemistry, Faculty of Mathematics and Natural Sciences, Heinrich Heine University, Düsseldorf, Germany
- Cluster of Excellence on Plant Sciences (CEPLAS), Düsseldorf, Germany
| | - M Eric Schranz
- Biosystematics Group, Department of Plant Sciences, Wageningen University, Wageningen, The Netherlands
| | - Andreas P M Weber
- Institute of Plant Biochemistry, Faculty of Mathematics and Natural Sciences, Heinrich Heine University, Düsseldorf, Germany
- Cluster of Excellence on Plant Sciences (CEPLAS), Düsseldorf, Germany
| | - Benjamin Stich
- Institute of Quantitative Genetics and Genomics of Plants, Faculty of Mathematics and Natural Sciences, Heinrich Heine University, Düsseldorf, Germany
- Cluster of Excellence on Plant Sciences (CEPLAS), Düsseldorf, Germany
- Max Planck Institute for Plant Breeding Research, Köln, Germany
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Furbank R, Kelly S, von Caemmerer S. Photosynthesis and food security: the evolving story of C 4 rice. Photosynth Res 2023; 158:121-130. [PMID: 37067631 PMCID: PMC10108777 DOI: 10.1007/s11120-023-01014-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Accepted: 03/15/2023] [Indexed: 06/19/2023]
Abstract
Traditional "Green Revolution" cereal breeding strategies to improve yield are now reaching a plateau in our principal global food crop rice. Photosynthesis has now become a major target of international consortia to increase yield potential. Synthetic biology is being used across multiple large projects to improve photosynthetic efficiency. This review follows the genesis and progress of one of the first of these consortia projects, now in its 13th year; the Bill and Melinda Gates funded C4 Rice Project. This project seeks to install the biochemical and anatomical attributes necessary to support C4 photosynthesis in the C3 crop rice. Here we address the advances made thus far in installing the biochemical pathway and some of the key targets yet to be reached.
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Affiliation(s)
- Robert Furbank
- Division of Plant Science, Centre of Excellence for Translational Photosynthesis, Research School of Biology, Australian National University, Acton, ACT, Australia.
| | - Steven Kelly
- Department of Plant Sciences, University of Oxford, Oxford, UK
| | - Susanne von Caemmerer
- Division of Plant Science, Centre of Excellence for Translational Photosynthesis, Research School of Biology, Australian National University, Acton, ACT, Australia
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10
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Billakurthi K, Hibberd JM. A rapid and robust leaf ablation method to visualize bundle sheath cells and chloroplasts in C 3 and C 4 grasses. Plant Methods 2023; 19:69. [PMID: 37408013 DOI: 10.1186/s13007-023-01041-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 06/19/2023] [Indexed: 07/07/2023]
Abstract
BACKGROUND It has been proposed that engineering the C4 photosynthetic pathway into C3 crops could significantly increase yield. This goal requires an increase in the chloroplast compartment of bundle sheath cells in C3 species. To facilitate large-scale testing of candidate regulators of chloroplast development in the rice bundle sheath, a simple and robust method to phenotype this tissue in C3 species is required. RESULTS We established a leaf ablation method to accelerate phenotyping of rice bundle sheath cells. The bundle sheath cells and chloroplasts were visualized using light and confocal laser microscopy. Bundle sheath cell dimensions, chloroplast area and chloroplast number per cell were measured from the images obtained by confocal laser microscopy. Bundle sheath cell dimensions of maize were also measured and compared with rice. Our data show that bundle sheath width but not length significantly differed between C3 rice and C4 maize. Comparison of paradermal versus transverse bundle sheath cell width indicated that bundle sheath cells were intact after leaf ablation. Moreover, comparisons of planar chloroplast areas and chloroplast numbers per bundle sheath cell between wild-type and transgenic rice lines expressing the maize GOLDEN-2 (ZmG2) showed that the leaf ablation method allowed differences in chloroplast parameters to be detected. CONCLUSIONS Leaf ablation is a simple approach to accessing bundle sheath cell files in C3 species. We show that this method is suitable for obtaining parameters associated with bundle sheath cell size, chloroplast area and chloroplast number per cell.
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Affiliation(s)
- Kumari Billakurthi
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, UK.
| | - Julian M Hibberd
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, UK
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11
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Daloso DDM, Morais EG, Oliveira E Silva KF, Williams TCR. Cell-type-specific metabolism in plants. Plant J 2023; 114:1093-1114. [PMID: 36987968 DOI: 10.1111/tpj.16214] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 03/20/2023] [Accepted: 03/25/2023] [Indexed: 05/31/2023]
Abstract
Every plant organ contains tens of different cell types, each with a specialized function. These functions are intrinsically associated with specific metabolic flux distributions that permit the synthesis of the ATP, reducing equivalents and biosynthetic precursors demanded by the cell. Investigating such cell-type-specific metabolism is complicated by the mosaic of different cells within each tissue combined with the relative scarcity of certain types. However, techniques for the isolation of specific cells, their analysis in situ by microscopy, or modeling of their function in silico have permitted insight into cell-type-specific metabolism. In this review we present some of the methods used in the analysis of cell-type-specific metabolism before describing what we know about metabolism in several cell types that have been studied in depth; (i) leaf source and sink cells; (ii) glandular trichomes that are capable of rapid synthesis of specialized metabolites; (iii) guard cells that must accumulate large quantities of the osmolytes needed for stomatal opening; (iv) cells of seeds involved in storage of reserves; and (v) the mesophyll and bundle sheath cells of C4 plants that participate in a CO2 concentrating cycle. Metabolism is discussed in terms of its principal features, connection to cell function and what factors affect the flux distribution. Demand for precursors and energy, availability of substrates and suppression of deleterious processes are identified as key factors in shaping cell-type-specific metabolism.
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Affiliation(s)
- Danilo de Menezes Daloso
- Lab Plant, Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Ceará, Fortaleza-CA, 60451-970, Brazil
| | - Eva Gomes Morais
- Lab Plant, Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Ceará, Fortaleza-CA, 60451-970, Brazil
| | - Karen Fernanda Oliveira E Silva
- Departamento de Botânica, Instituto de Ciências Biológicas, Universidade de Brasília, Asa Norte, Brasília-DF, 70910-900, Brazil
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12
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Li R, He Y, Chen J, Zheng S, Zhuang C. Research Progress in Improving Photosynthetic Efficiency. Int J Mol Sci 2023; 24:ijms24119286. [PMID: 37298238 DOI: 10.3390/ijms24119286] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 05/23/2023] [Accepted: 05/24/2023] [Indexed: 06/12/2023] Open
Abstract
Photosynthesis is the largest mass- and energy-conversion process on Earth, and it is the material basis for almost all biological activities. The efficiency of converting absorbed light energy into energy substances during photosynthesis is very low compared to theoretical values. Based on the importance of photosynthesis, this article summarizes the latest progress in improving photosynthesis efficiency from various perspectives. The main way to improve photosynthetic efficiency is to optimize the light reactions, including increasing light absorption and conversion, accelerating the recovery of non-photochemical quenching, modifying enzymes in the Calvin cycle, introducing carbon concentration mechanisms into C3 plants, rebuilding the photorespiration pathway, de novo synthesis, and changing stomatal conductance. These developments indicate that there is significant room for improvement in photosynthesis, providing support for improving crop yields and mitigating changes in climate conditions.
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Affiliation(s)
- Ruiqi Li
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, China
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Sciences, South China Agricultural University, Guangzhou 510642, China
| | - Ying He
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, China
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Sciences, South China Agricultural University, Guangzhou 510642, China
| | - Junyu Chen
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, China
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Sciences, South China Agricultural University, Guangzhou 510642, China
| | - Shaoyan Zheng
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, China
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Sciences, South China Agricultural University, Guangzhou 510642, China
| | - Chuxiong Zhuang
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, China
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Sciences, South China Agricultural University, Guangzhou 510642, China
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13
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Sierra J, Escobar-Tovar L, Leon P. Plastids: diving into their diversity, their functions, and their role in plant development. J Exp Bot 2023; 74:2508-2526. [PMID: 36738278 DOI: 10.1093/jxb/erad044] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 01/31/2023] [Indexed: 06/06/2023]
Abstract
Plastids are a group of essential, heterogenous semi-autonomous organelles characteristic of plants that perform photosynthesis and a diversity of metabolic pathways that impact growth and development. Plastids are remarkably dynamic and can interconvert in response to specific developmental and environmental cues, functioning as a central metabolic hub in plant cells. By far the best studied plastid is the chloroplast, but in recent years the combination of modern techniques and genetic analyses has expanded our current understanding of plastid morphological and functional diversity in both model and non-model plants. These studies have provided evidence of an unexpected diversity of plastid subtypes with specific characteristics. In this review, we describe recent findings that provide insights into the characteristics of these specialized plastids and their functions. We concentrate on the emerging evidence that supports the model that signals derived from particular plastid types play pivotal roles in plant development, environmental, and defense responses. Furthermore, we provide examples of how new technologies are illuminating the functions of these specialized plastids and the overall complexity of their differentiation processes. Finally, we discuss future research directions such as the use of ectopic plastid differentiation as a valuable tool to characterize factors involved in plastid differentiation. Collectively, we highlight important advances in the field that can also impact future agricultural and biotechnological improvement in plants.
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Affiliation(s)
- Julio Sierra
- Departamento de Biología Molecular de Plantas, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca 62210, México
| | - Lina Escobar-Tovar
- Departamento de Biología Molecular de Plantas, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca 62210, México
| | - Patricia Leon
- Departamento de Biología Molecular de Plantas, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca 62210, México
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14
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Luo W, Tan J, Li T, Feng Z, Ding Z, Xie X, Chen Y, Chen L, Liu YG, Zhu Q, Guo J. Overexpression of maize GOLDEN2 in rice and maize calli improves regeneration by activating chloroplast development. Sci China Life Sci 2023; 66:340-349. [PMID: 35982378 DOI: 10.1007/s11427-022-2149-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 06/21/2022] [Indexed: 11/25/2022]
Abstract
Golden2 (G2), a member of the GARP transcription factor superfamily, regulates several biological processes and phytohormone signaling pathways in plants. In this study, we used a rice codon-optimized maize G2 gene (rZmG2) to improve the regeneration efficiency of rice and maize calli for genetic transformation. We isolated a promoter driving strong and callus-specific expression from rice to drive rZmG2 transcription from a transgene after transformation of two indica and two japonica rice cultivars. The resulting rZmG2 transgenic calli turned green in advance at the differentiation stage, thus significantly raising the regeneration rates of the transgenic indica and japonica rice plants relative to control transformations. Similar effect of this gene on improving maize transformation was also observed. Transcriptome sequencing and RT-qPCR analyses showed that many rice genes related to chloroplast development and phytohormones are upregulated in rZmG2-transgenic calli. These results demonstrate that rZmG2 can promote embryogenic callus differentiation and improve regeneration efficiency by activating chloroplast development and phytohormone pathways. We also established a heat-inducible Cre/loxP-based gene-excision system to remove rZmG2 and the antibiotic selectable gene after obtaining the transgenic plants. This study provides a useful tool for functional genomics work and biotechnology in plants.
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Affiliation(s)
- Wanni Luo
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Sciences, South China Agricultural University, SCAU, Guangzhou, 510642, China
| | - Jiantao Tan
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Sciences, South China Agricultural University, SCAU, Guangzhou, 510642, China
| | - Tie Li
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Sciences, South China Agricultural University, SCAU, Guangzhou, 510642, China
| | - Ziting Feng
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Sciences, South China Agricultural University, SCAU, Guangzhou, 510642, China
| | - Zhi Ding
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Sciences, South China Agricultural University, SCAU, Guangzhou, 510642, China
| | - Xianrong Xie
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Sciences, South China Agricultural University, SCAU, Guangzhou, 510642, China.,Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China
| | - Yuanling Chen
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Sciences, South China Agricultural University, SCAU, Guangzhou, 510642, China.,Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China
| | - Letian Chen
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Sciences, South China Agricultural University, SCAU, Guangzhou, 510642, China.,Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China
| | - Yao-Guang Liu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Sciences, South China Agricultural University, SCAU, Guangzhou, 510642, China.,Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China
| | - Qinlong Zhu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Sciences, South China Agricultural University, SCAU, Guangzhou, 510642, China. .,Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China.
| | - Jinxing Guo
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Sciences, South China Agricultural University, SCAU, Guangzhou, 510642, China. .,Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China.
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15
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Jin K, Chen G, Yang Y, Zhang Z, Lu T. Strategies for manipulating Rubisco and creating photorespiratory bypass to boost C 3 photosynthesis: Prospects on modern crop improvement. Plant Cell Environ 2023; 46:363-378. [PMID: 36444099 DOI: 10.1111/pce.14500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 11/25/2022] [Accepted: 11/26/2022] [Indexed: 06/16/2023]
Abstract
Photosynthesis is a process that uses solar energy to fix CO2 in the air and converts it into sugar, and ultimately powers almost all life activities on the earth. C3 photosynthesis is the most common form of photosynthesis in crops. Current efforts of increasing crop yields in response to growing global food requirement are mostly focused on improving C3 photosynthesis. In this review, we summarized the strategies of C3 photosynthesis improvement in terms of Rubisco properties and photorespiratory limitation. Potential engineered targets include Rubisco subunits and their catalytic sites, Rubisco assembly chaperones, and Rubisco activase. In addition, we reviewed multiple photorespiratory bypasses built by strategies of synthetic biology to reduce the release of CO2 and ammonia and minimize energy consumption by photorespiration. The potential strategies are suggested to enhance C3 photosynthesis and boost crop production.
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Affiliation(s)
- Kaining Jin
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, P. R. China
- Department of Plant Sciences, Centre for Crop Systems Analysis, Wageningen University & Research, Wageningen, The Netherlands
| | - Guoxin Chen
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, P. R. China
| | - Yirong Yang
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, P. R. China
| | - Zhiguo Zhang
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, P. R. China
| | - Tiegang Lu
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, P. R. China
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16
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Eckardt NA, Ainsworth EA, Bahuguna RN, Broadley MR, Busch W, Carpita NC, Castrillo G, Chory J, DeHaan LR, Duarte CM, Henry A, Jagadish SVK, Langdale JA, Leakey ADB, Liao JC, Lu KJ, McCann MC, McKay JK, Odeny DA, Jorge de Oliveira E, Platten JD, Rabbi I, Rim EY, Ronald PC, Salt DE, Shigenaga AM, Wang E, Wolfe M, Zhang X. Climate change challenges, plant science solutions. Plant Cell 2023; 35:24-66. [PMID: 36222573 PMCID: PMC9806663 DOI: 10.1093/plcell/koac303] [Citation(s) in RCA: 31] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Accepted: 09/29/2022] [Indexed: 06/16/2023]
Abstract
Climate change is a defining challenge of the 21st century, and this decade is a critical time for action to mitigate the worst effects on human populations and ecosystems. Plant science can play an important role in developing crops with enhanced resilience to harsh conditions (e.g. heat, drought, salt stress, flooding, disease outbreaks) and engineering efficient carbon-capturing and carbon-sequestering plants. Here, we present examples of research being conducted in these areas and discuss challenges and open questions as a call to action for the plant science community.
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Affiliation(s)
| | - Elizabeth A Ainsworth
- USDA ARS Global Change and Photosynthesis Research Unit, Urbana, Illinois 61801, USA
| | - Rajeev N Bahuguna
- Centre for Advanced Studies on Climate Change, Dr Rajendra Prasad Central Agricultural University, Samastipur 848125, Bihar, India
| | - Martin R Broadley
- School of Biosciences, University of Nottingham, Nottingham, NG7 2RD, UK
- Rothamsted Research, West Common, Harpenden, Hertfordshire, AL5 2JQ, UK
| | - Wolfgang Busch
- Plant Molecular and Cellular Biology Laboratory, Salk Institute for Biological Studies, La Jolla, California 92037, USA
| | - Nicholas C Carpita
- Biosciences Center, National Renewable Energy Laboratory, Golden, Colorado 80401, USA
| | - Gabriel Castrillo
- School of Biosciences, University of Nottingham, Nottingham, NG7 2RD, UK
- Future Food Beacon of Excellence, University of Nottingham, Nottingham, NG7 2RD, UK
| | - Joanne Chory
- Plant Molecular and Cellular Biology Laboratory, Salk Institute for Biological Studies, La Jolla, California 92037, USA
- Howard Hughes Medical Institute, Salk Institute for Biological Studies, La Jolla, California 92037, USA
| | | | - Carlos M Duarte
- Red Sea Research Center (RSRC) and Computational Bioscience Research Center, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia
| | - Amelia Henry
- International Rice Research Institute, Rice Breeding Innovations Platform, Los Baños, Laguna 4031, Philippines
| | - S V Krishna Jagadish
- Department of Plant and Soil Science, Texas Tech University, Lubbock, Texas 79410, USA
| | - Jane A Langdale
- Department of Biology, University of Oxford, Oxford, OX1 3RB, UK
| | - Andrew D B Leakey
- Department of Plant Biology, Department of Crop Sciences, and Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Illinois 61801, USA
| | - James C Liao
- Institute of Biological Chemistry, Academia Sinica, Taipei 11528, Taiwan
| | - Kuan-Jen Lu
- Institute of Biological Chemistry, Academia Sinica, Taipei 11528, Taiwan
| | - Maureen C McCann
- Biosciences Center, National Renewable Energy Laboratory, Golden, Colorado 80401, USA
| | - John K McKay
- Department of Agricultural Biology, Colorado State University, Fort Collins, Colorado 80523, USA
| | - Damaris A Odeny
- The International Crops Research Institute for the Semi-Arid Tropics–Eastern and Southern Africa, Gigiri 39063-00623, Nairobi, Kenya
| | | | - J Damien Platten
- International Rice Research Institute, Rice Breeding Innovations Platform, Los Baños, Laguna 4031, Philippines
| | - Ismail Rabbi
- International Institute of Tropical Agriculture (IITA), PMB 5320 Ibadan, Oyo, Nigeria
| | - Ellen Youngsoo Rim
- Department of Plant Pathology and the Genome Center, University of California, Davis, California 95616, USA
| | - Pamela C Ronald
- Department of Plant Pathology and the Genome Center, University of California, Davis, California 95616, USA
- Innovative Genomics Institute, Berkeley, California 94704, USA
| | - David E Salt
- School of Biosciences, University of Nottingham, Nottingham, NG7 2RD, UK
- Future Food Beacon of Excellence, University of Nottingham, Nottingham, NG7 2RD, UK
| | - Alexandra M Shigenaga
- Department of Plant Pathology and the Genome Center, University of California, Davis, California 95616, USA
| | - Ertao Wang
- National Key Laboratory of Plant Molecular Genetics, Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Marnin Wolfe
- Auburn University, Dept. of Crop Soil and Environmental Sciences, College of Agriculture, Auburn, Alabama 36849, USA
| | - Xiaowei Zhang
- National Key Laboratory of Plant Molecular Genetics, Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
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17
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Leister D. Enhancing the light reactions of photosynthesis: Strategies, controversies, and perspectives. Mol Plant 2023; 16:4-22. [PMID: 35996755 DOI: 10.1016/j.molp.2022.08.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2022] [Revised: 07/26/2022] [Accepted: 08/16/2022] [Indexed: 06/15/2023]
Abstract
Photosynthesis is central to life on Earth, employing sunlight, water, and carbon dioxide to produce chemical energy and oxygen. It is generally accepted that boosting its efficiency offers one promising way to increase crop yields under agronomically realistic conditions. Since the components, structure, and regulatory mechanisms of the light reactions of photosynthesis are well understood, concepts for enhancing the process have been suggested and partially tested. These approaches vary in complexity, from targeting single components to comprehensive redesign of the whole process on the scales from single cells or tissues to whole canopies. Attempts to enhance light utilization per leaf, by decreasing pigmentation, increasing levels of photosynthetic proteins, prolonging the lifespan of the photosynthetic machinery, or massive reconfiguration of the photosynthetic machinery and the incorporation of nanomaterials, are discussed in this review first. Secondly, strategies intended to optimize the acclimation of photosynthesis to changes in the environment are presented, including redesigning mechanisms to dissipate excess excitation energy (e.g., non-photochemical quenching) or reduction power (e.g., flavodiiron proteins). Moreover, schemes for improving acclimation, inspired by natural or laboratory-induced adaptation, are introduced. However, all these endeavors are still in an early exploratory phase and/or have not resulted in the desired outcome, largely because photosynthesis is embedded within large networks of closely interacting cellular and metabolic processes, which can vary among species and even cultivars. This explains why integrated, systems-wide approaches are required to achieve the breakthroughs required for effectively increasing crop yields.
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Affiliation(s)
- Dario Leister
- Plant Molecular Biology, Faculty of Biology, Ludwig-Maximilians-University (LMU) Munich, Martinsried-Planegg, D-82152 Munich, Germany.
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18
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Munekage YN, Taniguchi YY. A scheme for C 4 evolution derived from a comparative analysis of the closely related C 3, C 3-C 4 intermediate, C 4-like, and C 4 species in the genus Flaveria. Plant Mol Biol 2022; 110:445-454. [PMID: 35119574 DOI: 10.1007/s11103-022-01246-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Accepted: 01/21/2022] [Indexed: 06/14/2023]
Abstract
A comparative analysis of the genus Flaveria showed a C4 evolutionary process in which the anatomical and metabolic features of C4 photosynthesis were gradually acquired through C3-C4 intermediate stages. C4 photosynthesis has been acquired in multiple lineages of angiosperms during evolution to suppress photorespiration. Crops that perform C4 photosynthesis exhibit high rates of CO2 assimilation and high grain production even under high-temperature in semiarid environments; therefore, engineering C4 photosynthesis in C3 plants is of great importance in the application field. The genus Flaveria contains a large number of C3, C3-C4 intermediate, C4-like, and C4 species, making it a good model genus to study the evolution of C4 photosynthesis, and these studies indicate the direction for C4 engineering. C4 photosynthesis was acquired gradually through the C3-C4 intermediate stage. First, a two-celled C2 cycle called C2 photosynthesis was acquired by localizing glycine decarboxylase activity in the mitochondria of bundle sheath cells. With the development of two-cell metabolism, anatomical features also changed. Next, the replacement of the two-celled C2 cycle by the two-celled C4 cycle was induced by the acquisition of cell-selective expression in addition to the upregulation of enzymes in the C4 cycle during the C3-C4 intermediate stage. This was supported by an increase in cyclic electron transport activity in response to an increase in the ATP/NADPH demand for metabolism. Suppression of the C3 cycle in mesophyll cells was induced after the functional establishment of the C4 cycle, and optimization of electron transport by suppressing the activity of photosystem II also occurred during the final phase of C4 evolution.
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Affiliation(s)
- Yuri N Munekage
- School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo, 669-1337, Japan.
| | - Yukimi Y Taniguchi
- School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo, 669-1337, Japan
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19
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Takao K, Shirakura H, Hatakeyama Y, Ueno O. Salt stress induces Kranz anatomy and expression of C 4 photosynthetic enzymes in the amphibious sedge Eleocharis vivipara. Photosynth Res 2022; 153:93-102. [PMID: 35352232 DOI: 10.1007/s11120-022-00913-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 03/10/2022] [Indexed: 06/14/2023]
Abstract
Eleocharis vivipara Link is a unique amphibious leafless plant of the Cyperaceae. The terrestrial form develops culms with Kranz anatomy and C4-like traits, while the submerged form does culms with non-Kranz anatomy and C3 traits. The submerged form develops new culms with C4-like mode when exposed to air or exogenous abscisic acid. In this study, we investigated whether salt stress (0.05-0.3 M NaCl) has a similar effect. When the submerged form was grown for one month in solutions of 0.1 M NaCl and more, culm growth was strongly suppressed. However, these plants slowly developed new culms that had Kranz anatomy with chloroplast-abundant Kranz bundle sheath cells. Although the culms of the submerged form had only few stomata, culms grown in the NaCl solution had many stomata. The NaCl-grown culms also accumulated large amounts of C4 photosynthetic enzymes (phosphoenolpyruvate carboxylase and pyruvate Pi dikinase), and the cellular localization patterns of these enzymes and ribulose 1,5-bisphosphate carboxylase/oxygenase were similar to those in terrestrial culms. Accumulation of C4 enzymes increased in mature culms of the submerged form (with non-Kranz anatomy) when exposed to 0.2 M NaCl solution for one week. These results suggest that salt stress induces development of Kranz anatomy and expression of C4 photosynthetic enzymes in the submerged C3 form of E. vivipara, whereas the anatomical and biochemical traits of C4 photosynthesis appear to be regulated independently.
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Affiliation(s)
- Kazuya Takao
- Graduate School of Bioresources and Environmental Sciences, Kyushu University, Motooka, Fukuoka, 819-0395, Japan
| | - Hiroko Shirakura
- School of Agriculture, Kyushu University, Motooka, Fukuoka, 819-0395, Japan
| | - Yuto Hatakeyama
- Graduate School of Bioresources and Environmental Sciences, Kyushu University, Motooka, Fukuoka, 819-0395, Japan
| | - Osamu Ueno
- Faculty of Agriculture, Kyushu University, Motooka, Fukuoka, 819-0395, Japan.
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20
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Sharwood RE, Quick WP, Sargent D, Estavillo GM, Silva-Perez V, Furbank RT. Mining for allelic gold: finding genetic variation in photosynthetic traits in crops and wild relatives. J Exp Bot 2022; 73:3085-3108. [PMID: 35274686 DOI: 10.1093/jxb/erac081] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Accepted: 02/28/2022] [Indexed: 06/14/2023]
Abstract
Improvement of photosynthetic traits in crops to increase yield potential and crop resilience has recently become a major breeding target. Synthetic biology and genetic technologies offer unparalleled opportunities to create new genetics for photosynthetic traits driven by existing fundamental knowledge. However, large 'gene bank' collections of germplasm comprising historical collections of crop species and their relatives offer a wealth of opportunities to find novel allelic variation in the key steps of photosynthesis, to identify new mechanisms and to accelerate genetic progress in crop breeding programmes. Here we explore the available genetic resources in food and fibre crops, strategies to selectively target allelic variation in genes underpinning key photosynthetic processes, and deployment of this variation via gene editing in modern elite material.
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Affiliation(s)
- Robert E Sharwood
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
- ARC Centre of Excellence for Translational Photosynthesis, Research School of Biology, Australian National University, Canberra, ACT, Australia
| | - W Paul Quick
- ARC Centre of Excellence for Translational Photosynthesis, Research School of Biology, Australian National University, Canberra, ACT, Australia
- International Rice Research Institute, Los Baños, Laguna, Philippines
| | - Demi Sargent
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | | | | | - Robert T Furbank
- ARC Centre of Excellence for Translational Photosynthesis, Research School of Biology, Australian National University, Canberra, ACT, Australia
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21
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Mercado MA, Studer AJ. Meeting in the Middle: Lessons and Opportunities from Studying C 3-C 4 Intermediates. Annu Rev Plant Biol 2022; 73:43-65. [PMID: 35231181 DOI: 10.1146/annurev-arplant-102720-114201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The discovery of C3-C4 intermediate species nearly 50 years ago opened up a new avenue for studying the evolution of photosynthetic pathways. Intermediate species exhibit anatomical, biochemical, and physiological traits that range from C3 to C4. A key feature of C3-C4 intermediates that utilize C2 photosynthesis is the improvement in photosynthetic efficiency compared with C3 species. Although the recruitment of some core enzymes is shared across lineages, there is significant variability in gene expression patterns, consistent with models that suggest numerous evolutionary paths from C3 to C4 photosynthesis. Despite the many evolutionary trajectories, the recruitment of glycine decarboxylase for C2 photosynthesis is likely required. As technologies enable high-throughput genotyping and phenotyping, the discovery of new C3-C4 intermediates species will enrich comparisons between evolutionary lineages. The investigation of C3-C4 intermediate species will enhance our understanding of photosynthetic mechanisms and evolutionary processes and will potentially aid in crop improvement.
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Affiliation(s)
| | - Anthony J Studer
- Department of Crop Sciences, University of Illinois, Urbana, Illinois, USA; ,
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22
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Bianconi ME, Sotelo G, Curran EV, Milenkovic V, Samaritani E, Dunning LT, Bertolino LT, Osborne CP, Christin PA. Upregulation of C 4 characteristics does not consistently improve photosynthetic performance in intraspecific hybrids of a grass. Plant Cell Environ 2022. [PMID: 35201618 DOI: 10.1101/2021.08.10.455822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
C4 photosynthesis is thought to have evolved via intermediate stages, with changes towards the C4 phenotype gradually enhancing photosynthetic performance. This hypothesis is widely supported by modelling studies, but experimental tests are missing. Mixing of C4 components to generate artificial intermediates can be achieved via crossing, and the grass Alloteropsis semialata represents an outstanding study system since it includes C4 and non-C4 populations. Here, we analyse F1 hybrids between C3 and C4 , and C3 +C4 and C4 genotypes to determine whether the acquisition of C4 characteristics increases photosynthetic performance. The hybrids have leaf anatomical characters and C4 gene expression profiles that are largely intermediate between those of their parents. Carbon isotope ratios are similarly intermediate, which suggests that a partial C4 cycle coexists with C3 carbon fixation in the hybrids. This partial C4 phenotype is associated with C4 -like photosynthetic efficiency in C3 +C4 × C4 , but not in C3 × C4 hybrids, which are overall less efficient than both parents. Our results support the hypothesis that the photosynthetic gains from the upregulation of C4 characteristics depend on coordinated changes in anatomy and biochemistry. The order of acquisition of C4 components is thus constrained, with C3 +C4 species providing an essential step for C4 evolution.
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Affiliation(s)
- Matheus E Bianconi
- Ecology and Evolutionary Biology, School of Biosciences, University of Sheffield, Western Bank, Sheffield, UK
| | - Graciela Sotelo
- Ecology and Evolutionary Biology, School of Biosciences, University of Sheffield, Western Bank, Sheffield, UK
| | - Emma V Curran
- Ecology and Evolutionary Biology, School of Biosciences, University of Sheffield, Western Bank, Sheffield, UK
| | - Vanja Milenkovic
- Ecology and Evolutionary Biology, School of Biosciences, University of Sheffield, Western Bank, Sheffield, UK
| | - Emanuela Samaritani
- Ecology and Evolutionary Biology, School of Biosciences, University of Sheffield, Western Bank, Sheffield, UK
| | - Luke T Dunning
- Ecology and Evolutionary Biology, School of Biosciences, University of Sheffield, Western Bank, Sheffield, UK
| | - Lígia T Bertolino
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Western Bank, Sheffield, UK
| | - Colin P Osborne
- Plants, Photosynthesis and Soil, School of Biosciences, University of Sheffield, Western Bank, Sheffield, UK
| | - Pascal-Antoine Christin
- Ecology and Evolutionary Biology, School of Biosciences, University of Sheffield, Western Bank, Sheffield, UK
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23
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Bianconi ME, Sotelo G, Curran EV, Milenkovic V, Samaritani E, Dunning LT, Bertolino LT, Osborne CP, Christin P. Upregulation of C 4 characteristics does not consistently improve photosynthetic performance in intraspecific hybrids of a grass. Plant Cell Environ 2022; 45:1398-1411. [PMID: 35201618 PMCID: PMC9314825 DOI: 10.1111/pce.14301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 11/20/2021] [Accepted: 11/21/2021] [Indexed: 06/14/2023]
Abstract
C4 photosynthesis is thought to have evolved via intermediate stages, with changes towards the C4 phenotype gradually enhancing photosynthetic performance. This hypothesis is widely supported by modelling studies, but experimental tests are missing. Mixing of C4 components to generate artificial intermediates can be achieved via crossing, and the grass Alloteropsis semialata represents an outstanding study system since it includes C4 and non-C4 populations. Here, we analyse F1 hybrids between C3 and C4 , and C3 +C4 and C4 genotypes to determine whether the acquisition of C4 characteristics increases photosynthetic performance. The hybrids have leaf anatomical characters and C4 gene expression profiles that are largely intermediate between those of their parents. Carbon isotope ratios are similarly intermediate, which suggests that a partial C4 cycle coexists with C3 carbon fixation in the hybrids. This partial C4 phenotype is associated with C4 -like photosynthetic efficiency in C3 +C4 × C4 , but not in C3 × C4 hybrids, which are overall less efficient than both parents. Our results support the hypothesis that the photosynthetic gains from the upregulation of C4 characteristics depend on coordinated changes in anatomy and biochemistry. The order of acquisition of C4 components is thus constrained, with C3 +C4 species providing an essential step for C4 evolution.
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Affiliation(s)
- Matheus E. Bianconi
- Ecology and Evolutionary Biology, School of BiosciencesUniversity of SheffieldWestern BankSheffieldUK
| | - Graciela Sotelo
- Ecology and Evolutionary Biology, School of BiosciencesUniversity of SheffieldWestern BankSheffieldUK
| | - Emma V. Curran
- Ecology and Evolutionary Biology, School of BiosciencesUniversity of SheffieldWestern BankSheffieldUK
| | - Vanja Milenkovic
- Ecology and Evolutionary Biology, School of BiosciencesUniversity of SheffieldWestern BankSheffieldUK
| | - Emanuela Samaritani
- Ecology and Evolutionary Biology, School of BiosciencesUniversity of SheffieldWestern BankSheffieldUK
| | - Luke T. Dunning
- Ecology and Evolutionary Biology, School of BiosciencesUniversity of SheffieldWestern BankSheffieldUK
| | - Lígia T. Bertolino
- Plants, Photosynthesis and Soil, School of BiosciencesUniversity of SheffieldWestern BankSheffieldUK
| | - Colin P. Osborne
- Plants, Photosynthesis and Soil, School of BiosciencesUniversity of SheffieldWestern BankSheffieldUK
| | - Pascal‐Antoine Christin
- Ecology and Evolutionary Biology, School of BiosciencesUniversity of SheffieldWestern BankSheffieldUK
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24
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Khoshravesh R, Hoffmann N, Hanson DT. Leaf microscopy applications in photosynthesis research: identifying the gaps. J Exp Bot 2022; 73:1868-1893. [PMID: 34986250 DOI: 10.1093/jxb/erab548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Accepted: 12/10/2021] [Indexed: 06/14/2023]
Abstract
Leaf imaging via microscopy has provided critical insights into research on photosynthesis at multiple junctures, from the early understanding of the role of stomata, through elucidating C4 photosynthesis via Kranz anatomy and chloroplast arrangement in single cells, to detailed explorations of diffusion pathways and light utilization gradients within leaves. In recent decades, the original two-dimensional (2D) explorations have begun to be visualized in three-dimensional (3D) space, revising our understanding of structure-function relationships between internal leaf anatomy and photosynthesis. In particular, advancing new technologies and analyses are providing fresh insight into the relationship between leaf cellular components and improving the ability to model net carbon fixation, water use efficiency, and metabolite turnover rate in leaves. While ground-breaking developments in imaging tools and techniques have expanded our knowledge of leaf 3D structure via high-resolution 3D and time-series images, there is a growing need for more in vivo imaging as well as metabolite imaging. However, these advances necessitate further improvement in microscopy sciences to overcome the unique challenges a green leaf poses. In this review, we discuss the available tools, techniques, challenges, and gaps for efficient in vivo leaf 3D imaging, as well as innovations to overcome these difficulties.
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Affiliation(s)
| | - Natalie Hoffmann
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
| | - David T Hanson
- Department of Biology, University of New Mexico, Albuquerque, NM, USA
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25
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Hughes TE, Langdale JA. SCARECROW is deployed in distinct contexts during rice and maize leaf development. Development 2022; 149:274881. [PMID: 35293577 PMCID: PMC8995083 DOI: 10.1242/dev.200410] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 02/28/2022] [Indexed: 12/25/2022]
Abstract
ABSTRACT
The flexible deployment of developmental regulators is an increasingly appreciated aspect of plant development and evolution. The GRAS transcription factor SCARECROW (SCR) regulates the development of the endodermis in Arabidopsis and maize roots, but during leaf development it regulates the development of distinct cell types; bundle-sheath in Arabidopsis and mesophyll in maize. In rice, SCR is implicated in stomatal patterning, but it is unknown whether this function is additional to a role in inner leaf patterning. Here, we demonstrate that two duplicated SCR genes function redundantly in rice. Contrary to previous reports, we show that these genes are necessary for stomatal development, with stomata virtually absent from leaves that are initiated after germination of mutants. The stomatal regulator OsMUTE is downregulated in Osscr1;Osscr2 mutants, indicating that OsSCR acts early in stomatal development. Notably, Osscr1;Osscr2 mutants do not exhibit the inner leaf patterning perturbations seen in Zmscr1;Zmscr1h mutants, and Zmscr1;Zmscr1h mutants do not exhibit major perturbations in stomatal patterning. Taken together, these results indicate that SCR was deployed in different developmental contexts after the divergence of rice and maize around 50 million years ago.
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Affiliation(s)
- Thomas E. Hughes
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford, OX1 3RB, UK
| | - Jane A. Langdale
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford, OX1 3RB, UK
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26
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Fan Y, Scafaro AP, Asao S, Furbank RT, Agostino A, Day DA, von Caemmerer S, Danila FR, Rug M, Webb D, Lee J, Atkin OK. Dark respiration rates are not determined by differences in mitochondrial capacity, abundance and ultrastructure in C 4 leaves. Plant Cell Environ 2022; 45:1257-1269. [PMID: 35048399 DOI: 10.1111/pce.14267] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 12/28/2021] [Indexed: 06/14/2023]
Abstract
Our understanding of the regulation of respiration in C4 plants, where mitochondria play different roles in the different types of C4 photosynthetic pathway, remains limited. We examined how leaf dark respiration rates (Rdark ), in the presence and absence of added malate, vary in monocots representing the three classical biochemical types of C4 photosynthesis (NADP-ME, NAD-ME and PCK) using intact leaves and extracted bundle sheath strands. In particular, we explored to what extent rates of Rdark are associated with mitochondrial number, volume and ultrastructure. Based on examination of a single species per C4 type, we found that the respiratory response of NAD-ME and PCK type bundle sheath strands to added malate was associated with differences in mitochondrial number, volume, and/or ultrastructure, while NADP-ME type bundle sheath strands did not respond to malate addition. In general, mitochondrial traits reflected the contributions mitochondria make to photosynthesis in the three C4 types. However, despite the obvious differences in mitochondrial traits, no clear correlation was observed between these traits and Rdark . We suggest that Rdark is primarily driven by cellular maintenance demands and not mitochondrial composition per se, in a manner that is somewhat independent of mitochondrial organic acid cycling in the light.
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Affiliation(s)
- Yuzhen Fan
- Research School of Biology, ARC Centre of Excellence in Plant Energy Biology, The Australian National University, Canberra, Australian Capital Territory, Australia
- Research School of Biology, Division of Plant Sciences, The Australian National University, Canberra, Australian Capital Territory, Australia
| | - Andrew P Scafaro
- Research School of Biology, ARC Centre of Excellence in Plant Energy Biology, The Australian National University, Canberra, Australian Capital Territory, Australia
- Research School of Biology, Division of Plant Sciences, The Australian National University, Canberra, Australian Capital Territory, Australia
| | - Shinichi Asao
- Research School of Biology, Division of Plant Sciences, The Australian National University, Canberra, Australian Capital Territory, Australia
| | - Robert T Furbank
- Research School of Biology, Division of Plant Sciences, The Australian National University, Canberra, Australian Capital Territory, Australia
- Research School of Biology, ARC Centre of Excellence for Translational Photosynthesis, The Australian National University, Canberra, Australian Capital Territory, Australia
| | - Antony Agostino
- Research School of Biology, Division of Plant Sciences, The Australian National University, Canberra, Australian Capital Territory, Australia
| | - David A Day
- College of Science and Engineering, Flinders University, Adelaide, South Australia, Australia
| | - Susanne von Caemmerer
- Research School of Biology, Division of Plant Sciences, The Australian National University, Canberra, Australian Capital Territory, Australia
- Research School of Biology, ARC Centre of Excellence for Translational Photosynthesis, The Australian National University, Canberra, Australian Capital Territory, Australia
| | - Florence R Danila
- Research School of Biology, Division of Plant Sciences, The Australian National University, Canberra, Australian Capital Territory, Australia
- Research School of Biology, ARC Centre of Excellence for Translational Photosynthesis, The Australian National University, Canberra, Australian Capital Territory, Australia
| | - Melanie Rug
- Centre for Advanced Microscopy, The Australian National University, Canberra, Australian Capital Territory, Australia
| | - Daryl Webb
- Centre for Advanced Microscopy, The Australian National University, Canberra, Australian Capital Territory, Australia
| | - Jiwon Lee
- Centre for Advanced Microscopy, The Australian National University, Canberra, Australian Capital Territory, Australia
| | - Owen K Atkin
- Research School of Biology, ARC Centre of Excellence in Plant Energy Biology, The Australian National University, Canberra, Australian Capital Territory, Australia
- Research School of Biology, Division of Plant Sciences, The Australian National University, Canberra, Australian Capital Territory, Australia
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27
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Cackett L, Luginbuehl LH, Schreier TB, Lopez-Juez E, Hibberd JM. Chloroplast development in green plant tissues: the interplay between light, hormone, and transcriptional regulation. New Phytol 2022; 233:2000-2016. [PMID: 34729790 DOI: 10.1111/nph.17839] [Citation(s) in RCA: 45] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Accepted: 10/09/2021] [Indexed: 05/20/2023]
Abstract
Chloroplasts are best known for their role in photosynthesis, but they also allow nitrogen and sulphur assimilation, amino acid, fatty acid, nucleotide and hormone synthesis. How chloroplasts develop is therefore relevant to these diverse and fundamental biological processes, but also to attempts at their rational redesign. Light is strictly required for chloroplast formation in all angiosperms and directly regulates the expression of hundreds of chloroplast-related genes. Light also modulates the levels of several hormones including brassinosteriods, cytokinins, auxins and gibberellins, which themselves control chloroplast development particularly during early stages of plant development. Transcription factors such as GOLDENLIKE1&2 (GLK1&2), GATA NITRATE-INDUCIBLE CARBON METABOLISM-INVOLVED (GNC) and CYTOKININ-RESPONSIVE GATA FACTOR 1 (CGA1) act downstream of both light and phytohormone signalling to regulate chloroplast development. Thus, in green tissues transcription factors, light signalling and hormone signalling form a complex network regulating the transcription of chloroplast- and photosynthesis-related genes to control the development and number of chloroplasts per cell. We use this conceptual framework to identify points of regulation that could be harnessed to modulate chloroplast abundance and increase photosynthetic efficiency of crops, and to highlight future avenues to overcome gaps in current knowledge.
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Affiliation(s)
- Lee Cackett
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, UK
| | - Leonie H Luginbuehl
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, UK
| | - Tina B Schreier
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, UK
| | - Enrique Lopez-Juez
- Department of Biological Sciences, Royal Holloway University of London, Egham, TW20 0EX, UK
| | - Julian M Hibberd
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, UK
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28
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Fan Y, Asao S, Furbank RT, von Caemmerer S, Day DA, Tcherkez G, Sage TL, Sage RF, Atkin OK. The crucial roles of mitochondria in supporting C 4 photosynthesis. New Phytol 2022; 233:1083-1096. [PMID: 34669188 DOI: 10.1111/nph.17818] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Accepted: 10/18/2021] [Indexed: 06/13/2023]
Abstract
C4 photosynthesis involves a series of biochemical and anatomical traits that significantly improve plant productivity under conditions that reduce the efficiency of C3 photosynthesis. We explore how evolution of the three classical biochemical types of C4 photosynthesis (NADP-ME, NAD-ME and PCK types) has affected the functions and properties of mitochondria. Mitochondria in C4 NAD-ME and PCK types play a direct role in decarboxylation of metabolites for C4 photosynthesis. Mitochondria in C4 PCK type also provide ATP for C4 metabolism, although this role for ATP provision is not seen in NAD-ME type. Such involvement has increased mitochondrial abundance/size and associated enzymatic capacity, led to changes in mitochondrial location and ultrastructure, and altered the role of mitochondria in cellular carbon metabolism in the NAD-ME and PCK types. By contrast, these changes in mitochondrial properties are absent in the C4 NADP-ME type and C3 leaves, where mitochondria play no direct role in photosynthesis. From an eco-physiological perspective, rates of leaf respiration in darkness vary considerably among C4 species but does not differ systematically among the three C4 types. This review outlines further mitochondrial research in key areas central to the engineering of the C4 pathway into C3 plants and to the understanding of variation in rates of C4 dark respiration.
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Affiliation(s)
- Yuzhen Fan
- ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
- Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
| | - Shinichi Asao
- ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
| | - Robert T Furbank
- Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
- ARC Centre of Excellence for Translational Photosynthesis, Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
| | - Susanne von Caemmerer
- Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
- ARC Centre of Excellence for Translational Photosynthesis, Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
| | - David A Day
- College of Science and Engineering, Flinders University, GPO Box 2100, Adelaide, SA, 5001, Australia
| | - Guillaume Tcherkez
- Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
- Institut de Recherche en Horticulture et Semences, INRA and University of Angers, Beaucouzé, 49070, France
| | - Tammy L Sage
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, M5S 3B2, Canada
| | - Rowan F Sage
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, M5S 3B2, Canada
| | - Owen K Atkin
- ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
- Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
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29
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Chen L, Ganguly DR, Shafik SH, Ermakova M, Pogson BJ, Grof CPL, Sharwood RE, Furbank RT. Elucidating the role of SWEET13 in phloem loading of the C 4 grass Setaria viridis. Plant J 2022; 109:615-632. [PMID: 34780111 DOI: 10.1111/tpj.15581] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 10/11/2021] [Accepted: 11/08/2021] [Indexed: 06/13/2023]
Abstract
Photosynthetic efficiency and sink demand are tightly correlated with rates of phloem loading, where maintaining low cytosolic sugar concentrations is paramount to prevent the downregulation of photosynthesis. Sugars Will Eventually be Exported Transporters (SWEETs) are thought to have a pivotal role in the apoplastic phloem loading of C4 grasses. SWEETs have not been well studied in C4 species, and their investigation is complicated by photosynthesis taking place across two cell types and, therefore, photoassimilate export can occur from either one. SWEET13 homologues in C4 grasses have been proposed to facilitate apoplastic phloem loading. Here, we provide evidence for this hypothesis using the C4 grass Setaria viridis. Expression analyses on the leaf gradient of C4 species Setaria and Sorghum bicolor show abundant transcript levels for SWEET13 homologues. Carbohydrate profiling along the Setaria leaf shows total sugar content to be significantly higher in the mature leaf tip compared with the younger tissue at the base. We present the first known immunolocalization results for SvSWEET13a and SvSWEET13b using novel isoform-specific antisera. These results show localization to the bundle sheath and phloem parenchyma cells of both minor and major veins. We further present the first transport kinetics study of C4 monocot SWEETs by using a Xenopus laevis oocyte heterologous expression system. We demonstrate that SvSWEET13a and SvSWEET13b are high-capacity transporters of glucose and sucrose, with a higher apparent Vmax for sucrose, compared with glucose, typical of clade III SWEETs. Collectively, these results provide evidence for an apoplastic phloem loading pathway in Setaria and possibly other C4 species.
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Affiliation(s)
- Lily Chen
- Research School of Biology, ARC Centre of Excellence for Translational Photosynthesis, Australian National University, Canberra, Australian Capital Territory, 2601, Australia
- School of Science, Hawkesbury Institute for the Environment, Western Sydney University, Hawkesbury Campus, New South Wales, 2753, Australia
| | - Diep R Ganguly
- ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, Australian National University, Canberra, Australian Capital Territory, 2601, Australia
- CSIRO Synthetic Biology Future Science Platform, Canberra, Australian Capital Territory, 2601, Australia
| | - Sarah H Shafik
- Research School of Biology, Australian National University, Canberra, Australian Capital Territory, 2601, Australia
| | - Maria Ermakova
- Research School of Biology, ARC Centre of Excellence for Translational Photosynthesis, Australian National University, Canberra, Australian Capital Territory, 2601, Australia
| | - Barry J Pogson
- ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, Australian National University, Canberra, Australian Capital Territory, 2601, Australia
| | - Christopher P L Grof
- Centre for Plant Science, School of Environmental and Life Sciences, College of Engineering Science and Environment, University of Newcastle, Callaghan, New South Wales, 2308, Australia
| | - Robert E Sharwood
- Research School of Biology, ARC Centre of Excellence for Translational Photosynthesis, Australian National University, Canberra, Australian Capital Territory, 2601, Australia
- School of Science, Hawkesbury Institute for the Environment, Western Sydney University, Hawkesbury Campus, New South Wales, 2753, Australia
| | - Robert T Furbank
- Research School of Biology, ARC Centre of Excellence for Translational Photosynthesis, Australian National University, Canberra, Australian Capital Territory, 2601, Australia
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30
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Yong MT, Solis CA, Amatoury S, Sellamuthu G, Rajakani R, Mak M, Venkataraman G, Shabala L, Zhou M, Ghannoum O, Holford P, Huda S, Shabala S, Chen ZH. Proto Kranz-like leaf traits and cellular ionic regulation are associated with salinity tolerance in a halophytic wild rice. Stress Biol 2022; 2:8. [PMID: 37676369 PMCID: PMC10441962 DOI: 10.1007/s44154-021-00016-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2021] [Accepted: 11/17/2021] [Indexed: 09/08/2023]
Abstract
Species of wild rice (Oryza spp.) possess a wide range of stress tolerance traits that can be potentially utilized in breeding climate-resilient cultivated rice cultivars (Oryza sativa) thereby aiding global food security. In this study, we conducted a greenhouse trial to evaluate the salinity tolerance of six wild rice species, one cultivated rice cultivar (IR64) and one landrace (Pokkali) using a range of electrophysiological, imaging, and whole-plant physiological techniques. Three wild species (O. latifolia, O. officinalis and O. coarctata) were found to possess superior salinity stress tolerance. The underlying mechanisms, however, were strikingly different. Na+ accumulation in leaves of O. latifolia, O. officinalis and O. coarctata were significantly higher than the tolerant landrace, Pokkali. Na+ accumulation in mesophyll cells was only observed in O. coarctata, suggesting that O. officinalis and O. latifolia avoid Na+ accumulation in mesophyll by allocating Na+ to other parts of the leaf. The finding also suggests that O. coarctata might be able to employ Na+ as osmolyte without affecting its growth. Further study of Na+ allocation in leaves will be helpful to understand the mechanisms of Na+ accumulation in these species. In addition, O. coarctata showed Proto Kranz-like leaf anatomy (enlarged bundle sheath cells and lower numbers of mesophyll cells), and higher expression of C4-related genes (e.g., NADPME, PPDK) and was a clear outlier with respect to salinity tolerance among the studied wild and cultivated Oryza species. The unique phylogenetic relationship of O. coarctata with C4 grasses suggests the potential of this species for breeding rice with high photosynthetic rate under salinity stress in the future.
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Affiliation(s)
- Miing-Tiem Yong
- School of Science, Western Sydney University, Penrith, NSW, 2751, Australia
| | - Celymar Angela Solis
- School of Science, Western Sydney University, Penrith, NSW, 2751, Australia
- Tasmanian Institute of Agriculture, College of Science and Engineering, University of Tasmania, Hobart, Tasmania, 7001, Australia
| | - Samuel Amatoury
- School of Science, Western Sydney University, Penrith, NSW, 2751, Australia
| | - Gothandapani Sellamuthu
- Plant Molecular Biology Laboratory, M. S. Swaminathan Research Foundation, III Cross Street, Taramani Institutional Area, -600113, Chennai, India
| | - Raja Rajakani
- Plant Molecular Biology Laboratory, M. S. Swaminathan Research Foundation, III Cross Street, Taramani Institutional Area, -600113, Chennai, India
| | - Michelle Mak
- School of Science, Western Sydney University, Penrith, NSW, 2751, Australia
| | - Gayatri Venkataraman
- Plant Molecular Biology Laboratory, M. S. Swaminathan Research Foundation, III Cross Street, Taramani Institutional Area, -600113, Chennai, India
| | - Lana Shabala
- Tasmanian Institute of Agriculture, College of Science and Engineering, University of Tasmania, Hobart, Tasmania, 7001, Australia
| | - Meixue Zhou
- Tasmanian Institute of Agriculture, College of Science and Engineering, University of Tasmania, Hobart, Tasmania, 7001, Australia
| | - Oula Ghannoum
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, 2751, Australia
| | - Paul Holford
- School of Science, Western Sydney University, Penrith, NSW, 2751, Australia
| | - Samsul Huda
- School of Science, Western Sydney University, Penrith, NSW, 2751, Australia
| | - Sergey Shabala
- Tasmanian Institute of Agriculture, College of Science and Engineering, University of Tasmania, Hobart, Tasmania, 7001, Australia.
- International Research Centre for Environmental Membrane Biology, Foshan University, Foshan, 528000, China.
| | - Zhong-Hua Chen
- School of Science, Western Sydney University, Penrith, NSW, 2751, Australia.
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, 2751, Australia.
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31
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Yeh SY, Lin HH, Chang YM, Chang YL, Chang CK, Huang YC, Ho YW, Lin CY, Zheng JZ, Jane WN, Ng CY, Lu MY, Lai IL, To KY, Li WH, Ku MSB. Maize Golden2-like transcription factors boost rice chloroplast development, photosynthesis, and grain yield. Plant Physiol 2022; 188:442-459. [PMID: 34747472 PMCID: PMC9049120 DOI: 10.1093/plphys/kiab511] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Accepted: 10/10/2021] [Indexed: 05/03/2023]
Abstract
Chloroplasts are the sites for photosynthesis, and two Golden2-like factors act as transcriptional activators of chloroplast development in rice (Oryza sativa L.) and maize (Zea mays L.). Rice OsGLK1 and OsGLK2 are orthologous to maize ZmGLK1 (ZmG1) and ZmGLK2 (ZmG2), respectively. However, while rice OsGLK1 and OsGLK2 act redundantly to regulate chloroplast development in mesophyll cells, maize ZmG1 and ZmG2 are functionally specialized and expressed in different cell-specific manners. To boost rice chloroplast development and photosynthesis, we generated transgenic rice plants overexpressing ZmG1 and ZmG2, individually or simultaneously, with constitutive promoters (pZmUbi::ZmG1 and p35S::ZmG2) or maize promoters (pZmG1::ZmG1, pZmG2::ZmG2, and pZmG1::ZmG1/pZmG2::ZmG2). Both ZmG1 and ZmG2 genes were highly expressed in transgenic rice leaves. Moreover, ZmG1 and ZmG2 showed coordinated expression in pZmG1::ZmG1/pZmG2::ZmG2 plants. All Golden2-like (GLK) transgenic plants had higher chlorophyll and protein contents, Rubisco activities and photosynthetic rates per unit leaf area in flag leaves. However, the highest grain yields occurred when maize promoters were used; pZmG1::ZmG1, pZmG2::ZmG2, and pZmG1::ZmG1/pZmG2::ZmG2 transgenic plants showed increases in grain yield by 51%, 47%, and 70%, respectively. In contrast, the pZmUbi::ZmG1 plant produced smaller seeds without yield increases. Transcriptome analysis indicated that maize GLKs act as master regulators promoting the expression of both photosynthesis-related and stress-responsive regulatory genes in both rice shoot and root. Thus, by promoting these important functions under the control of their own promoters, maize GLK1 and GLK2 genes together dramatically improved rice photosynthetic performance and productivity. A similar approach can potentially improve the productivity of many other crops.
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Affiliation(s)
| | | | - Yao-Ming Chang
- Biodiversity Research Center, Academia
Sinica, Taipei 11529, Taiwan
- Institute of Biomedical Sciences, Academia
Sinica, Taipei 11529, Taiwan
| | - Yu-Lun Chang
- Department of Bioagricultural Science, National
Chiayi University, Chiayi 600, Taiwan
| | - Chao-Kang Chang
- Biodiversity Research Center, Academia
Sinica, Taipei 11529, Taiwan
| | - Yi-Cin Huang
- Biodiversity Research Center, Academia
Sinica, Taipei 11529, Taiwan
| | - Yi-Wen Ho
- Biodiversity Research Center, Academia
Sinica, Taipei 11529, Taiwan
| | - Chu-Yin Lin
- Biodiversity Research Center, Academia
Sinica, Taipei 11529, Taiwan
| | - Jun-Ze Zheng
- Department of Bioagricultural Science, National
Chiayi University, Chiayi 600, Taiwan
| | - Wann-Neng Jane
- Institute of Plant and Microbial Biology, Academia
Sinica, Taipei 11529, Taiwan
| | - Chun-Yeung Ng
- Biodiversity Research Center, Academia
Sinica, Taipei 11529, Taiwan
| | - Mei-Yeh Lu
- Biodiversity Research Center, Academia
Sinica, Taipei 11529, Taiwan
| | - I-Ling Lai
- Graduate Institute of Bioresources, National
Pingtung University of Science and Technology, Pingtung 912,
Taiwan
| | - Kin-Ying To
- Agricultural Biotechnology Research Center, Academia
Sinica, Taipei 11529, Taiwan
| | - Wen-Hsiung Li
- Biodiversity Research Center, Academia
Sinica, Taipei 11529, Taiwan
- Department of Ecology and Evolution, University of
Chicago, Chicago, Illinois 60637, USA
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32
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Iñiguez C, Aguiló-Nicolau P, Galmés J. Improving photosynthesis through the enhancement of Rubisco carboxylation capacity. Biochem Soc Trans 2021; 49:2007-2019. [PMID: 34623388 DOI: 10.1042/bst20201056] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 09/07/2021] [Accepted: 09/09/2021] [Indexed: 12/14/2022]
Abstract
Rising human population, along with the reduction in arable land and the impacts of global change, sets out the need for continuously improving agricultural resource use efficiency and crop yield (CY). Bioengineering approaches for photosynthesis optimization have largely demonstrated the potential for enhancing CY. This review is focused on the improvement of Rubisco functioning, which catalyzes the rate-limiting step of CO2 fixation required for plant growth, but also catalyzes the ribulose-bisphosphate oxygenation initiating the carbon and energy wasteful photorespiration pathway. Rubisco carboxylation capacity can be enhanced by engineering the Rubisco large and/or small subunit genes to improve its catalytic traits, or by engineering the mechanisms that provide enhanced Rubisco expression, activation and/or elevated [CO2] around the active sites to favor carboxylation over oxygenation. Recent advances have been made in the expression, assembly and activation of foreign (either natural or mutant) faster and/or more CO2-specific Rubisco versions. Some components of CO2 concentrating mechanisms (CCMs) from bacteria, algae and C4 plants has been successfully expressed in tobacco and rice. Still, none of the transformed plant lines expressing foreign Rubisco versions and/or simplified CCM components were able to grow faster than wild type plants under present atmospheric [CO2] and optimum conditions. However, the results obtained up to date suggest that it might be achievable in the near future. In addition, photosynthetic and yield improvements have already been observed when manipulating Rubisco quantity and activation degree in crops. Therefore, engineering Rubisco carboxylation capacity continues being a promising target for the improvement in photosynthesis and yield.
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Affiliation(s)
- Concepción Iñiguez
- Research Group on Plant Biology Under Mediterranean Conditions, Universitat de les Illes Balears-INAGEA, Palma, Balearic Islands, Spain
- Department of Ecology, Faculty of Sciences, University of Málaga, Málaga, Spain
| | - Pere Aguiló-Nicolau
- Research Group on Plant Biology Under Mediterranean Conditions, Universitat de les Illes Balears-INAGEA, Palma, Balearic Islands, Spain
| | - Jeroni Galmés
- Research Group on Plant Biology Under Mediterranean Conditions, Universitat de les Illes Balears-INAGEA, Palma, Balearic Islands, Spain
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33
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Lee D, Hua L, Khoshravesh R, Giuliani R, Kumar I, Cousins A, Sage TL, Hibberd JM, Brutnell TP. Engineering chloroplast development in rice through cell-specific control of endogenous genetic circuits. Plant Biotechnol J 2021; 19:2291-2303. [PMID: 34328250 PMCID: PMC8541780 DOI: 10.1111/pbi.13660] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 06/21/2021] [Accepted: 06/25/2021] [Indexed: 05/03/2023]
Abstract
The engineering of C4 photosynthetic activity into the C3 plant rice has the potential to nearly double rice yields. To engineer a two-cell photosynthetic system in rice, the rice bundle sheath (BS) must be rewired to enhance photosynthetic capacity. Here, we show that BS chloroplast biogenesis is enhanced when the transcriptional activator, Oryza sativa Cytokinin GATA transcription factor 1 (OsCGA1), is driven by a vascular specific promoter. Ectopic expression of OsCGA1 resulted in increased BS chloroplast planar area and increased expression of photosynthesis-associated nuclear genes (PhANG), required for the biogenesis of photosynthetically active chloroplasts in BS cells of rice. A further refinement using a DNAse dead Cas9 (dCas9) activation module driven by the same cell-type specific promoter, directed enhanced chloroplast development of the BS cells when gRNA sequences were delivered by the dCas9 module to the promoter of the endogenous OsCGA1 gene. Single gRNA expression was sufficient to mediate the transactivation of both the endogenous gene and a transgenic GUS reporter fused with OsCGA1 promoter. Our results illustrate the potential for tissue-specific dCas9-activation and the co-regulation of genes needed for multistep engineering of C4 rice.
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Affiliation(s)
| | - Lei Hua
- Department of Plant SciencesUniversity of CambridgeCambridgeUK
| | - Roxana Khoshravesh
- Department of Ecology and Evolutionary Biologythe University of TorontoTorontoONCanada
- Department of Biologythe University of New MexicoAlbuquerqueNMUSA
| | - Rita Giuliani
- School of Biological SciencesWashington State UniversityPullmanWAUSA
| | | | - Asaph Cousins
- School of Biological SciencesWashington State UniversityPullmanWAUSA
| | - Tammy L. Sage
- Department of Ecology and Evolutionary Biologythe University of TorontoTorontoONCanada
| | | | - Thomas P. Brutnell
- Donald Danforth Plant Science CenterSt. LouisMOUSA
- Biotechnology Research InstituteChinese Academy of Agricultural SciencesBeijingChina
- Joint Laboratory for Photosynthesis Enhancement and C4 Rice DevelopmentBiotechnology Research InstituteChinese Academy of Agricultural SciencesBeijingChina
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34
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Abstract
With a rapidly growing world population and dwindling natural resources, we are now facing the enormous challenge of increasing crop yields while simultaneously improving the efficiency of resource utilization. Introduction of C4 photosynthesis into C3 crops is widely accepted as a key strategy to meet this challenge because C4 plants are more efficient than C3 plants in photosynthesis and resource usage, particularly in hot climates, where the potential for productivity is high. Lending support to the feasibility of this C3-to-C4 engineering, evidence indicates that C4 photosynthesis has evolved from C3 photosynthesis in multiple lineages. Nevertheless, C3-to-C4 engineering is not an easy task, as several features essential to C4 photosynthesis must be introduced into C3 plants. One such feature is the spatial separation of the two phases of photosynthesis (CO2 fixation and carbohydrate synthesis) into the mesophyll and bundle sheath cells, respectively. Another feature is the Kranz anatomy, characterized by a close association between the mesophyll and bundle sheath (BS) cells (1:1 ratio). These anatomical features, along with a C4-specific carbon fixation enzyme (PEPC), form a CO2-concentration mechanism that ensures a high photosynthetic efficiency. Much effort has been taken in the past to introduce the C4 mechanism into C3 plants, but none of these attempts has met with success, which is in my opinion due to a lack of system-level understanding and manipulation of the C3 and C4 pathways. As a prerequisite for the C3-to-C4 engineering, I propose that not only the mechanisms that control the Kranz anatomy and cell-type-specific expression in C3 and C4 plants must be elucidated, but also a good understanding of the gene regulatory network underlying C3 and C4 photosynthesis must be achieved. In this review, I first describe the past and current efforts to increase photosynthetic efficiency in C3 plants and their limitations; I then discuss a systems approach to tackling down this challenge, some practical issues, and recent technical innovations that would help us to solve these problems.
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Affiliation(s)
- Hongchang Cui
- Department of Biological Science, Florida State University, Tallahassee, FL, United States
- College of Life Science, Northwest Science University of Agriculture and Forestry, Yangling, China
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35
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Hua L, Stevenson SR, Reyna-Llorens I, Xiong H, Kopriva S, Hibberd JM. The bundle sheath of rice is conditioned to play an active role in water transport as well as sulfur assimilation and jasmonic acid synthesis. Plant J 2021; 107:268-286. [PMID: 33901336 DOI: 10.1111/tpj.15292] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 04/16/2021] [Accepted: 04/20/2021] [Indexed: 06/12/2023]
Abstract
Leaves comprise multiple cell types but our knowledge of the patterns of gene expression that underpin their functional specialization is fragmentary. Our understanding and ability to undertake the rational redesign of these cells is therefore limited. We aimed to identify genes associated with the incompletely understood bundle sheath of C3 plants, which represents a key target associated with engineering traits such as C4 photosynthesis into Oryza sativa (rice). To better understand the veins, bundle sheath and mesophyll cells of rice, we used laser capture microdissection followed by deep sequencing. Gene expression of the mesophyll is conditioned to allow coenzyme metabolism and redox homeostasis, as well as photosynthesis. In contrast, the bundle sheath is specialized in water transport, sulphur assimilation and jasmonic acid biosynthesis. Despite the small chloroplast compartment of bundle sheath cells, substantial photosynthesis gene expression was detected. These patterns of gene expression were not associated with the presence or absence of specific transcription factors in each cell type, but were instead associated with gradients in expression across the leaf. Comparative analysis with C3 Arabidopsis identified a small gene set preferentially expressed in the bundle sheath cells of both species. This gene set included genes encoding transcription factors from 14 orthogroups and proteins allowing water transport, sulphate assimilation and jasmonic acid synthesis. The most parsimonious explanation for our findings is that bundle sheath cells from the last common ancestor of rice and Arabidopsis were specialized in this manner, and as the species diverged these patterns of gene expression have been maintained.
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Affiliation(s)
- Lei Hua
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, UK
| | - Sean R Stevenson
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, UK
| | - Ivan Reyna-Llorens
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, UK
| | - Haiyan Xiong
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, UK
| | - Stanislav Kopriva
- Institute for Plant Sciences, Cluster of Excellence on Plant Sciences (CEPLAS), University of Cologne, Zülpicher Str. 47b, Cologne, 50674, Germany
| | - Julian M Hibberd
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, UK
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36
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Robil JM, Gao K, Neighbors CM, Boeding M, Carland FM, Bunyak F, McSteen P. grasviq: an image analysis framework for automatically quantifying vein number and morphology in grass leaves. Plant J 2021; 107:629-648. [PMID: 33914380 DOI: 10.1111/tpj.15299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 04/16/2021] [Accepted: 04/21/2021] [Indexed: 06/12/2023]
Abstract
Beyond facilitating transport and providing mechanical support to the leaf, veins have important roles in the performance and productivity of plants and the ecosystem. In recent decades, computational image analysis has accelerated the extraction and quantification of vein traits, benefiting fields of research from agriculture to climatology. However, most of the existing leaf vein image analysis programs have been developed for the reticulate venation found in dicots. Despite the agroeconomic importance of cereal grass crops, like Oryza sativa (rice) and Zea mays (maize), a dedicated image analysis program for the parallel venation found in monocots has yet to be developed. To address the need for an image-based vein phenotyping tool for model and agronomic grass species, we developed the grass vein image quantification (grasviq) framework. Designed specifically for parallel venation, this framework automatically segments and quantifies vein patterns from images of cleared leaf pieces using classical computer vision techniques. Using image data sets from maize inbred lines and auxin biosynthesis and transport mutants in maize, we demonstrate the utility of grasviq for quantifying important vein traits, including vein density, vein width and interveinal distance. Furthermore, we show that the framework can resolve quantitative differences and identify vein patterning defects, which is advantageous for genetic experiments and mutant screens. We report that grasviq can perform high-throughput vein quantification, with precision on a par with that of manual quantification. Therefore, we envision that grasviq will be adopted for vein phenomics in maize and other grass species.
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Affiliation(s)
- Janlo M Robil
- Division of Biological Sciences, Interdisciplinary Plant Group, and Missouri Maize Center, University of Missouri, Columbia, Missouri, 65211, USA
| | - Ke Gao
- Department of Electrical Engineering and Computer Science, University of Missouri, Columbia, Missouri, 65211, USA
| | - Claire M Neighbors
- Division of Biological Sciences, Interdisciplinary Plant Group, and Missouri Maize Center, University of Missouri, Columbia, Missouri, 65211, USA
| | - Michael Boeding
- Department of Electrical Engineering and Computer Science, University of Missouri, Columbia, Missouri, 65211, USA
| | - Francine M Carland
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, Connecticut, 06520, USA
| | - Filiz Bunyak
- Department of Electrical Engineering and Computer Science, University of Missouri, Columbia, Missouri, 65211, USA
| | - Paula McSteen
- Division of Biological Sciences, Interdisciplinary Plant Group, and Missouri Maize Center, University of Missouri, Columbia, Missouri, 65211, USA
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Maheshwari C, Coe RA, Karki S, Covshoff S, Tapia R, Tyagi A, Hibberd JM, Furbank RT, Quick WP, Lin HC. Targeted knockdown of ribulose-1, 5-bisphosphate carboxylase-oxygenase in rice mesophyll cells. J Plant Physiol 2021; 260:153395. [PMID: 33684805 PMCID: PMC8090977 DOI: 10.1016/j.jplph.2021.153395] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 02/06/2021] [Accepted: 02/21/2021] [Indexed: 05/22/2023]
Abstract
We generated antisense constructs targeting two of the five Rubisco small subunit genes (OsRBCS2 and 4) which account for between 30-40 % of the RBCS transcript abundance in leaf blades. The constructs were driven by a maize phosphoenolpyruvate carboxylase (PEPC) promoter known to have enriched expression in mesophyll cells (MCs). In the resulting lines leaf, Rubisco protein content was reduced by between 30-50 % and CO2 assimilation rate was limited under photorespiratory and non-photorespiratory conditions. A relationship between Rubisco protein content and CO2 assimilation rate was found. This was associated with a significant reduction in dry biomass accumulation and grain yield of between 37-70%. In addition to serving as a resource for reducing Rubisco accumulation in a cell-preferential manner, these lines allow us to characterize gene function and isoform specific suppression on photosynthesis and growth. Our results suggest that the knockdown of multiple genes is required to completely reduce Rubisco accumulation in MCs.
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Affiliation(s)
- Chirag Maheshwari
- C4Rice Centre, International Rice Research Institute (IRRI), Los Baños, Philippines
| | - Robert A Coe
- C4Rice Centre, International Rice Research Institute (IRRI), Los Baños, Philippines
| | - Shanta Karki
- C4Rice Centre, International Rice Research Institute (IRRI), Los Baños, Philippines
| | - Sarah Covshoff
- Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA, United Kingdom
| | - Ronald Tapia
- C4Rice Centre, International Rice Research Institute (IRRI), Los Baños, Philippines
| | - Aruna Tyagi
- Division of Biochemistry, ICAR-Indian Agricultural Research Institute, New Delhi, India
| | - Julian M Hibberd
- Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA, United Kingdom
| | - Robert T Furbank
- ARC Centre of Excellence for Translational Photosynthesis, Research School of Biology, The Australian National University, Acton, 2601, Australia
| | - William Paul Quick
- C4Rice Centre, International Rice Research Institute (IRRI), Los Baños, Philippines; Department of Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, United Kingdom
| | - Hsiang-Chun Lin
- C4Rice Centre, International Rice Research Institute (IRRI), Los Baños, Philippines.
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38
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Jiang D, Wang F, Zhang H, Gao W, Tong X, Lv C, Chen G. Formation of Proto-Kranz in C3 Rice Induced by Spike-Stalk Injection Method. Int J Mol Sci 2021; 22:4305. [PMID: 33919137 DOI: 10.3390/ijms22094305] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 04/15/2021] [Accepted: 04/19/2021] [Indexed: 01/08/2023] Open
Abstract
Introduction of C4 photosynthetic traits into C3 crops is an important strategy for improving photosynthetic capacity and productivity. Here, we report the research results of a variant line of sorghum-rice (SR) plant with big panicle and high spikelet density by introducing sorghum genome DNA into rice by spike-stalk injection. The whole-genome resequencing showed that a few sorghum genes could be integrated into the rice genome. Gene expression was confirmed for two C4 photosynthetic enzymes containing pyruvate, orthophosphate dikinase and phosphoenolpyruvate carboxykinase. Exogenous sorghum DNA integration induced a series of key traits associated with the C4 pathway called "proto-Kranz" anatomy, including leaf thickness, bundle sheath number and size, and chloroplast size in bundle sheath cells. Significantly, transgenic plants exhibited enhanced photosynthetic capacity resulting from both photosynthetic CO2-concentrating effect and improved energy balance, which led to an increase in carbohydrate levels and productivity. Furthermore, such rice plant exhibited delayed leaf senescence. In summary, this study provides a proof for the feasibility of inducing the transition from C3 leaf anatomy to proto-Kranz by spike-stalk injection to achieve efficient photosynthesis and increase productivity.
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39
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Yin X, Struik PC. Exploiting differences in the energy budget among C 4 subtypes to improve crop productivity. New Phytol 2021; 229:2400-2409. [PMID: 33067814 PMCID: PMC7894359 DOI: 10.1111/nph.17011] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2020] [Accepted: 10/11/2020] [Indexed: 05/22/2023]
Abstract
C4 crops of agricultural importance all belong to the NADP-malic enzyme (ME) subtype, and this subtype has been the template for C4 introductions into C3 crops, like rice, to improve their productivity. However, the ATP cost for the C4 cycle in both NADP-ME and NAD-ME subtypes accounts for > 40% of the total ATP requirement for CO2 assimilation. These high ATP costs, and the associated need for intense cyclic electron transport and low intrinsic quantum yield ΦCO2 , are major constraints in realizing strong improvements of canopy photosynthesis and crop productivity. Based on mathematical modelling, we propose a C4 ideotype that utilizes low chloroplastic ATP requirements present in the nondomesticated phosphoenolpyruvate carboxykinase (PEP-CK) subtype. The ideotype is a mixed form of NAD(P)-ME and PEP-CK types, requires no cyclic electron transport under low irradiances, and its theoretical ΦCO2 is c. 25% higher than that of a C4 crop type. Its cell-type-specific ATP and NADPH requirements can be fulfilled by local energy production. The ideotype is projected to have c. 10% yield advantage over NADP-ME-type crops and > 50% advantage over C3 counterparts. The ideotype provides a unique (theoretical) case where ΦCO2 could be improved, thereby paving a new avenue for improving photosynthesis in both C3 and C4 crops.
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Affiliation(s)
- Xinyou Yin
- Centre for Crop Systems AnalysisDepartment of Plant SciencesWageningen University & ResearchPO Box 430Wageningen6700 AKthe Netherlands
| | - Paul C. Struik
- Centre for Crop Systems AnalysisDepartment of Plant SciencesWageningen University & ResearchPO Box 430Wageningen6700 AKthe Netherlands
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40
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Wu L, Han L, Li Q, Wang G, Zhang H, Li L. Using Interactome Big Data to Crack Genetic Mysteries and Enhance Future Crop Breeding. Mol Plant 2021; 14:77-94. [PMID: 33340690 DOI: 10.1016/j.molp.2020.12.012] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 12/11/2020] [Accepted: 12/14/2020] [Indexed: 05/27/2023]
Abstract
The functional genes underlying phenotypic variation and their interactions represent "genetic mysteries". Understanding and utilizing these genetic mysteries are key solutions for mitigating the current threats to agriculture posed by population growth and individual food preferences. Due to advances in high-throughput multi-omics technologies, we are stepping into an Interactome Big Data era that is certain to revolutionize genetic research. In this article, we provide a brief overview of current strategies to explore genetic mysteries. We then introduce the methods for constructing and analyzing the Interactome Big Data and summarize currently available interactome resources. Next, we discuss how Interactome Big Data can be used as a versatile tool to dissect genetic mysteries. We propose an integrated strategy that could revolutionize genetic research by combining Interactome Big Data with machine learning, which involves mining information hidden in Big Data to identify the genetic models or networks that control various traits, and also provide a detailed procedure for systematic dissection of genetic mysteries,. Finally, we discuss three promising future breeding strategies utilizing the Interactome Big Data to improve crop yields and quality.
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Affiliation(s)
- Leiming Wu
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China
| | - Linqian Han
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China
| | - Qing Li
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China
| | - Guoying Wang
- Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Hongwei Zhang
- Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
| | - Lin Li
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China.
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41
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Abstract
C2 photosynthesis is a carbon concentrating mechanism that can increase net CO2 assimilation by capturing, concentrating and re-assimilating CO2 released by photorespiration. Empirical and modelling studies indicate that C2 plants assimilate more carbon than C3 plants under high temperature, bright light, and low CO2 conditions. I argue that engineering C2 photosynthesis into C3 crops is a promising approach to improve photosynthetic performance under these - and temporally heterogeneous - environments, and review the modifications that may re-create a C2 phenotype in C3 plants. Although a C2 engineering program would encounter many of the same challenges faced by C4 engineering programmes, the simpler leaf anatomical requirements make C2 engineering a feasible approach to improve crops in the medium term.
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42
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Hughes TE, Langdale JA. SCARECROW gene function is required for photosynthetic development in maize. Plant Direct 2020; 4:e00264. [PMID: 32999956 PMCID: PMC7507539 DOI: 10.1002/pld3.264] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 07/30/2020] [Accepted: 08/03/2020] [Indexed: 05/31/2023]
Abstract
C4 photosynthesis in grasses relies on a specialized leaf anatomy. In maize, this "Kranz" leaf anatomy is patterned in part by the duplicated SCARECROW (SCR) genes ZmSCR1 and ZmSCR1h. Here we show that in addition to patterning defects, chlorophyll content and levels of transcripts encoding Golden2-like regulators of chloroplast development are significantly lower in Zmscr1; Zmscr1h mutants than in wild-type. These perturbations are not associated with changes in chloroplast number, size, or ultrastructure. However, the maximum rates of carboxylation by ribulose bisphosphate carboxylase/oxygenase (RuBisCO, V cmax) and phosphoenolpyruvate carboxylase (PEPC, V pmax) are both reduced, leading to perturbed plant growth. The CO2 compensation point and 13C‰ of Zmscr1;Zmscr1h plants are both normal, indicating that a canonical C4 cycle is operating, albeit at reduced overall capacity. Taken together, our results reveal that the maize SCR genes, either directly or indirectly, play a role in photosynthetic development. SIGNIFICANCE STATEMENT SCARECROW (SCR) is one of the best studied plant developmental regulators, however, its role in downstream plant physiology is less well-understood. Here, we have demonstrated that SCR is required to establish and/or maintain photosynthetic capacity in maize leaves.
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Affiliation(s)
- Thomas E. Hughes
- Department of Plant SciencesUniversity of OxfordOxfordUnited Kingdom
| | - Jane A. Langdale
- Department of Plant SciencesUniversity of OxfordOxfordUnited Kingdom
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43
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Sadanandom A, Murchie EH. A Tropical Plant with Friends in Cold Places: The Formation of the UK Rice Research Community. Trends Plant Sci 2020; 25:421-422. [PMID: 32304652 DOI: 10.1016/j.tplants.2020.02.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 02/26/2020] [Accepted: 02/27/2020] [Indexed: 06/11/2023]
Abstract
The trend for translating fundamental plant science to applied solutions in agriculture has accelerated the formation of global networks and partnerships to achieve common global goals in food security. Here we highlight a thriving rice research community in the UK contributing to long-term approaches to understand rice biology.
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Affiliation(s)
- Ari Sadanandom
- Department of Biosciences, Durham University, Durham, UK.
| | - Erik H Murchie
- School of Biosciences, University of Nottingham, Nottingham, UK
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44
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Abstract
C4 photosynthesis evolved multiple times independently from ancestral C3 photosynthesis in a broad range of flowering land plant families and in both monocots and dicots. The evolution of C4 photosynthesis entails the recruitment of enzyme activities that are not involved in photosynthetic carbon fixation in C3 plants to photosynthesis. This requires a different regulation of gene expression as well as a different regulation of enzyme activities in comparison to the C3 context. Further, C4 photosynthesis relies on a distinct leaf anatomy that differs from that of C3, requiring a differential regulation of leaf development in C4. We summarize recent progress in the understanding of C4-specific features in evolution and metabolic regulation in the context of C4 photosynthesis.
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Affiliation(s)
- Urte Schlüter
- Institute of Plant Biochemistry, Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich Heine University, 40225 Düsseldorf, Germany; ,
| | - Andreas P M Weber
- Institute of Plant Biochemistry, Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich Heine University, 40225 Düsseldorf, Germany; ,
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45
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Kohli A, Miro B, Balié J, d’A Hughes J. Photosynthesis research: a model to bridge fundamental science, translational products, and socio-economic considerations in agriculture. J Exp Bot 2020; 71:2281-2298. [PMID: 32076700 PMCID: PMC7135011 DOI: 10.1093/jxb/eraa087] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2019] [Accepted: 02/19/2020] [Indexed: 05/04/2023]
Abstract
Despite impressive success in molecular physiological understanding of photosynthesis, and preliminary evidence on its potential for quantum shifts in agricultural productivity, the question remains of whether increased photosynthesis, without parallel fine-tuning of the associated processes, is enough. There is a distinct lack of formal socio-economic impact studies that address the critical questions of product profiling, cost-benefit analysis, environmental trade-offs, and technological and market forces in product acceptability. When a relatively well understood process gains enough traction for translational value, its broader scientific and technical gap assessment, in conjunction with its socio-economic impact assessment for success, should be a prerequisite. The successes in the upstream basic understanding of photosynthesis should be integrated with a gap analysis for downstream translational applications to impact the farmers' and customers' lifestyles and livelihoods. The purpose of this review is to assess how the laboratory, the field, and the societal demands from photosynthesis could generate a transformative product. Two crucial recommendations from the analysis of the state of knowledge and potential ways forward are (i) the formulation of integrative mega-projects, which span the multistakeholder spectrum, to ensure rapid success in harnessing the transformative power of photosynthesis; and (ii) stipulating spatiotemporal, labour, and economic criteria to stage-gate deliverables.
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Affiliation(s)
- Ajay Kohli
- International Rice Research Institute, Los Baños, Philippines
| | - Berta Miro
- International Rice Research Institute, Los Baños, Philippines
| | - Jean Balié
- International Rice Research Institute, Los Baños, Philippines
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Paul MJ, Watson A, Griffiths CA. Linking fundamental science to crop improvement through understanding source and sink traits and their integration for yield enhancement. J Exp Bot 2020; 71:2270-2280. [PMID: 31665486 PMCID: PMC7134924 DOI: 10.1093/jxb/erz480] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 10/11/2019] [Indexed: 05/19/2023]
Abstract
Understanding processes in sources and sinks that contribute to crop yields has taken years of painstaking research. For crop yield improvement, processes need to be understood as standalone mechanisms in addition to how these mechanisms perform at the crop level; currently there is often a chasm between the two. Fundamental mechanisms need to be considered in the context of crop ideotypes and the agricultural environment which is often more water limited than carbon limited. Different approaches for improvement should be considered, namely is there genetic variation? Or if not, could genetic modification, genome editing, or alternative approaches be utilized? Currently, there are few examples where genetic modification has improved intrinsic yield in the field for commercial application in a major crop. Genome editing, particularly of negative yield regulators as a first step, is providing new opportunities. Here we highlight key mechanisms in source and sink, arguing that for large yield increases integration of key processes is likely to produce the biggest successes within the framework of crop ideotypes with optimized phenology. We highlight a plethora of recent papers that show breakthroughs in fundamental science and the promise of the trehalose 6-phosphate signalling pathway, which regulates carbohydrate allocation which is key for many crop traits.
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Affiliation(s)
- Matthew J Paul
- Plant Science, Rothamsted Research, Harpenden, Hertfordshire, UK
- Correspondence:
| | - Amy Watson
- Plant Science, Rothamsted Research, Harpenden, Hertfordshire, UK
| | - Cara A Griffiths
- Plant Science, Rothamsted Research, Harpenden, Hertfordshire, UK
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47
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Li X, Wang P, Li J, Wei S, Yan Y, Yang J, Zhao M, Langdale JA, Zhou W. Maize GOLDEN2-LIKE genes enhance biomass and grain yields in rice by improving photosynthesis and reducing photoinhibition. Commun Biol 2020; 3:151. [PMID: 32238902 PMCID: PMC7113295 DOI: 10.1038/s42003-020-0887-3] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2019] [Accepted: 03/05/2020] [Indexed: 12/29/2022] Open
Abstract
Photosynthetic efficiency is a major target for improvement of crop yield potential under agricultural field conditions. Inefficiencies can occur in many steps of the photosynthetic process, from chloroplast biogenesis to functioning of the light harvesting and carbon fixation reactions. Nuclear-encoded GOLDEN2-LIKE (GLK) transcription factors regulate some of the earliest steps by activating target genes encoding chloroplast-localized and photosynthesis-related proteins. Here we show that constitutive expression of maize GLK genes in rice leads to enhanced levels of chlorophylls and pigment-protein antenna complexes, and that these increases lead to improved light harvesting efficiency via photosystem II in field-grown plants. Increased levels of xanthophylls further buffer the negative effects of photoinhibition under high or fluctuating light conditions by facilitating greater dissipation of excess absorbed energy as heat. Significantly, the enhanced photosynthetic capacity of field-grown transgenic plants resulted in increased carbohydrate levels and a 30–40% increase in both vegetative biomass and grain yield. Li et al. improve photosynthetic efficiency in rice by constitutively expressing maize GOLDEN2-like (GLK) genes (ZmG2 and ZmGLK1). They are able to reduce photoinhibition and enhance the photosynthetic potential as well as increase the carbohydrate, biomass and grain yield.
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Affiliation(s)
- Xia Li
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, 100081, Beijing, China
| | - Peng Wang
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford, OX1 3RB, UK.,CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Jing Li
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, 100081, Beijing, China
| | - Shaobo Wei
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, 100081, Beijing, China
| | - Yanyan Yan
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, 100081, Beijing, China
| | - Jun Yang
- Shanghai Key Laboratory of Plant Functional Genomics and Resources, Shanghai Chenshan Plant Science Research Center, Chinese Academy of Sciences, Shanghai Chenshan Botanical Garden, 201602, Shanghai, China
| | - Ming Zhao
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, 100081, Beijing, China
| | - Jane A Langdale
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford, OX1 3RB, UK
| | - Wenbin Zhou
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, 100081, Beijing, China.
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48
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Hendron RW, Kelly S. Subdivision of Light Signaling Networks Contributes to Partitioning of C 4 Photosynthesis. Plant Physiol 2020; 182:1297-1309. [PMID: 31862840 PMCID: PMC7054874 DOI: 10.1104/pp.19.01053] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 12/04/2019] [Indexed: 05/29/2023]
Abstract
Plants coordinate the expression of photosynthesis-related genes in response to growth and environmental changes. In species that conduct two-cell C4 photosynthesis, expression of photosynthesis genes is partitioned such that leaf mesophyll and bundle sheath cells accumulate different components of the photosynthetic pathway. The identities of the regulatory networks that facilitate this partitioning are unknown. Here, we show that differences in light perception between mesophyll and bundle sheath cells facilitate differential regulation and accumulation of photosynthesis gene transcripts in the C4 crop maize (Zea mays). Key components of the photosynthesis gene regulatory network differentially accumulated between mesophyll and bundle sheath cells, indicative of differential network activity across cell types. We further show that blue (but not red) light is necessary and sufficient to activate photosystem II assembly in mesophyll cells in etiolated maize. Finally, we demonstrate that 61% of all light-induced mesophyll and bundle sheath genes were induced only by blue light or only by red light, but not both. These findings provide evidence that subdivision of light signaling networks is a component of cellular partitioning of C4 photosynthesis in maize.
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Affiliation(s)
- Ross-W Hendron
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, United Kingdom
| | - Steven Kelly
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, United Kingdom
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Abstract
After entering the leaf, CO2 faces an intricate pathway to the site of photosynthetic fixation embedded within the chloroplasts. The efficiency of CO2 flux is hindered by a number of structural and biochemical barriers which, together, define the ease of flow of the gas within the leaf, termed mesophyll conductance. Previous authors have identified the key elements of this pathway, raising the prospect of engineering the system to improve CO2 flux and, thus, to increase leaf photosynthetic efficiency. In this review, we provide a perspective on the potential for improving the individual elements that contribute to this complex parameter. We lay particular emphasis on generation of the cellular architecture of the leaf which sets the initial boundaries of a number of mesophyll conductance parameters, incorporating an overview of the molecular transport processes which have been proposed as major facilitators of CO2 flux across structural boundaries along the pathway. The review highlights the research areas where future effort might be invested to increase our fundamental understanding of mesophyll conductance and leaf function and, consequently, to enable translation of these findings to improve the efficiency of crop photosynthesis.
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Affiliation(s)
| | - Andrew J. Fleming
- Department of Animal and Plant SciencesUniversity of SheffieldWestern BankSheffieldS10 2TNUK
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50
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Ermakova M, Danila FR, Furbank RT, von Caemmerer S. On the road to C 4 rice: advances and perspectives. Plant J 2020; 101:940-950. [PMID: 31596523 PMCID: PMC7065233 DOI: 10.1111/tpj.14562] [Citation(s) in RCA: 92] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2019] [Revised: 09/27/2019] [Accepted: 10/03/2019] [Indexed: 05/18/2023]
Abstract
The international C4 rice consortium aims to introduce into rice a high capacity photosynthetic mechanism, the C4 pathway, to increase yield. The C4 pathway is characterised by a complex combination of biochemical and anatomical specialisation that ensures high CO2 partial pressure at RuBisCO sites in bundle sheath (BS) cells. Here we report an update of the progress of the C4 rice project. Since its inception in 2008 there has been an exponential growth in synthetic biology and molecular tools. Golden Gate cloning and synthetic promoter systems have facilitated gene building block approaches allowing multiple enzymes and metabolite transporters to be assembled and expressed from single gene constructs. Photosynthetic functionalisation of the BS in rice remains an important step and there has been some success overexpressing transcription factors in the cytokinin signalling network which influence chloroplast volume. The C4 rice project has rejuvenated the research interest in C4 photosynthesis. Comparative anatomical studies now point to critical features essential for the design. So far little attention has been paid to the energetics. C4 photosynthesis has a greater ATP requirement, which is met by increased cyclic electron transport in BS cells. We hypothesise that changes in energy statues may drive this increased capacity for cyclic electron flow without the need for further modification. Although increasing vein density will ultimately be necessary for high efficiency C4 rice, our modelling shows that small amounts of C4 photosynthesis introduced around existing veins could already provide benefits of increased photosynthesis on the road to C4 rice.
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Affiliation(s)
- Maria Ermakova
- Australian Research Council Centre of Excellence for Translational PhotosynthesisDivision of Plant ScienceResearch School of BiologyThe Australian National UniversityActonACT2601Australia
| | - Florence R. Danila
- Australian Research Council Centre of Excellence for Translational PhotosynthesisDivision of Plant ScienceResearch School of BiologyThe Australian National UniversityActonACT2601Australia
| | - Robert T. Furbank
- Australian Research Council Centre of Excellence for Translational PhotosynthesisDivision of Plant ScienceResearch School of BiologyThe Australian National UniversityActonACT2601Australia
| | - Susanne von Caemmerer
- Australian Research Council Centre of Excellence for Translational PhotosynthesisDivision of Plant ScienceResearch School of BiologyThe Australian National UniversityActonACT2601Australia
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