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Zhou H, Peng J, Zhao W, Zeng Y, Xie K, Huang G. Leaf diffusional capacity largely contributes to the reduced photosynthesis in rice plants under magnesium deficiency. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2024; 209:108565. [PMID: 38537380 DOI: 10.1016/j.plaphy.2024.108565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 03/07/2024] [Accepted: 03/24/2024] [Indexed: 04/06/2024]
Abstract
Numerous studies have clarified the impacts of magnesium (Mg) on leaf photosynthesis from the perspectives of protein synthesis, enzymes activation and carbohydrate partitioning. However, it still remains largely unknown how stomatal and mesophyll conductances (gs and gm, respectively) are regulated by Mg. In the present study, leaf gas exchanges, leaf hydraulic parameters, leaf structural traits and cell wall composition were examined in rice plants grown under high and low Mg treatments to elucidate the impacts of Mg on gs and gm. Our results showed that reduction of leaf photosynthesis under Mg deficiency was mainly caused by the decreased gm, followed by reduced leaf biochemical capacity and gs, and leaf outside-xylem hydraulic conductance (Kox) was the major factor restricting gs under Mg deficiency. Moreover, increased leaf hemicellulose, lignin and pectin contents and decreased cell wall effective porosity were observed in low Mg plants relative to high Mg plants. These results suggest that Kox and cell wall composition play important roles in regulating gs and gm, respectively, in rice plants under Mg shortages.
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Affiliation(s)
- Haimei Zhou
- Key Laboratory of Crop Physiology, Ecology and Genetic Breeding, Ministry of Education, School of Agricultural Sciences, Jiangxi Agricultural University, Nanchang, 330045, Jiangxi, China
| | - Jiang Peng
- Key Laboratory of Crop Physiology, Ecology and Genetic Breeding, Ministry of Education, School of Agricultural Sciences, Jiangxi Agricultural University, Nanchang, 330045, Jiangxi, China
| | - Wanling Zhao
- Key Laboratory of Crop Physiology, Ecology and Genetic Breeding, Ministry of Education, School of Agricultural Sciences, Jiangxi Agricultural University, Nanchang, 330045, Jiangxi, China
| | - Yongjun Zeng
- Key Laboratory of Crop Physiology, Ecology and Genetic Breeding, Ministry of Education, School of Agricultural Sciences, Jiangxi Agricultural University, Nanchang, 330045, Jiangxi, China
| | - Kailiu Xie
- School of Land Resources and Environment, Jiangxi Agricultural University, Nanchang, 330045, Jiangxi, China.
| | - Guanjun Huang
- Key Laboratory of Crop Physiology, Ecology and Genetic Breeding, Ministry of Education, School of Agricultural Sciences, Jiangxi Agricultural University, Nanchang, 330045, Jiangxi, China.
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Zhou Z, Su P, Yang J, Shi R, Ding X. Warming affects leaf light use efficiency and functional traits in alpine plants: evidence from a 4-year in-situ field experiment. FRONTIERS IN PLANT SCIENCE 2024; 15:1353762. [PMID: 38567127 PMCID: PMC10985207 DOI: 10.3389/fpls.2024.1353762] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Accepted: 02/27/2024] [Indexed: 04/04/2024]
Abstract
Introduction Light use efficiency (LUE) is a crucial determinant of plant productivity, while leaf functional traits directly affect ecosystem functions. However, it remains unclear how climate warming affects LUE and leaf functional traits of dominant species in alpine meadows. Methods We conducted a 4-year in-situ field warming experiment to investigate the eco-physiological characteristics for a dominant species (Elymus nutans) and a common species (Potentilla anserina) on the Tibetan Plateau. The leaf traits, photosynthesis and fluorescence characteristics were measured, along with the soil physical-chemical properties associated with the two species. Results and discussions Experimental warming increased the leaf LUE, maximum photochemical efficiency, non-photochemical quenching, relative water content and specific leaf area for both species. However, there was a decrease in leaf and soil element content. Different species exhibit varying adaptability to warming. Increasing temperature significantly increased the photosynthetic rate, stomatal conductance, transpiration rate, total water content, and specific leaf volume of E. nutans; however, all these traits exhibited an opposite trend in P. anserina. Warming has a direct negative impact on leaf LUE and an indirectly enhances LUE through its effects on leaf traits. The impact of warming on plant photosynthetic capacity is primarily mediated by soil nutrients and leaf traits. These results indicate that the two different species employ distinct adaptive strategies in response to climate change, which are related to their species-specific variations. Such changes can confer an adaptive advantage for plant to cope with environmental change and potentially lead to alterations to ecosystem structure and functioning.
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Affiliation(s)
- Zijuan Zhou
- Key Laboratory of Land Surface Process and Climate Change in Cold and Arid Regions, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, China
| | - Peixi Su
- Key Laboratory of Land Surface Process and Climate Change in Cold and Arid Regions, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, China
| | - Jianping Yang
- Key Laboratory of Land Surface Process and Climate Change in Cold and Arid Regions, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, China
| | - Rui Shi
- Key Laboratory of Land Surface Process and Climate Change in Cold and Arid Regions, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, China
| | - Xinjing Ding
- School of Geography, Liaoning Normal University, Dalian, China
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Luo D, Huang G, Zhang Q, Zhou G, Peng S, Li Y. Plasticity of mesophyll cell density and cell wall thickness and composition play a pivotal role in regulating plant growth and photosynthesis under shading in rapeseed. ANNALS OF BOTANY 2023; 132:963-978. [PMID: 37739395 PMCID: PMC10808032 DOI: 10.1093/aob/mcad140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 09/20/2023] [Indexed: 09/24/2023]
Abstract
BACKGROUND AND AIMS Plasticity of leaf growth and photosynthesis is an important strategy of plants to adapt to shading stress; however, their strategy of leaf development to achieve a simultaneous increase in leaf area and photosynthesis under shading remains unknown. METHODS In the present study, a pot experiment was conducted using three rapeseed genotypes of Huayouza 50 (HYZ50), Zhongshuang 11 (ZS11) and Huayouza 62 (HYZ62), and the responses of plant growth, leaf morphoanatomical traits, cell wall composition and photosynthesis to shading were investigated. KEY RESULTS Shading significantly increased leaf area per plant (LAplant) in all genotypes, but the increase in HYZ62 was greater than that in HYZ50 and ZS11. The greater increment of LAplant in HYZ62 was related to the larger decrease in leaf mass per area (LMA) and leaf density (LD), which were in turn related to less densely packed mesophyll cells and thinner cell walls (Tcw). Moreover, shading significantly increased photosynthesis in HYZ62 but significantly decreased it in HYZ50. The enhanced photosynthesis in HYZ62 was related to increased mesophyll conductance (gm) due primarily to thinner cell walls. CONCLUSIONS The data presented indicate that the different plasticity of mesophyll cell density, cell wall thickness and cell wall composition in response to shading can dramatically affect leaf growth and photosynthesis.
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Affiliation(s)
- Dongxu Luo
- Ministry of Agriculture Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
| | - Guanjun Huang
- Ministry of Agriculture Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
| | - Qiangqiang Zhang
- Rice Ecophysiology and Precise Management Laboratory, College of Agronomy, Anhui Agricultural University, Anhui 230036, China
| | - Guangsheng Zhou
- Ministry of Agriculture Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
| | - Shaobing Peng
- Ministry of Agriculture Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
| | - Yong Li
- Ministry of Agriculture Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
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Ozawa Y, Tanaka A, Suzuki T, Sugiura D. Sink-source imbalance triggers delayed photosynthetic induction: Transcriptomic and physiological evidence. PHYSIOLOGIA PLANTARUM 2023; 175:e14000. [PMID: 37882282 DOI: 10.1111/ppl.14000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 08/01/2023] [Accepted: 08/06/2023] [Indexed: 10/27/2023]
Abstract
Sink-source imbalance causes accumulation of nonstructural carbohydrates (NSCs) and photosynthetic downregulation. However, despite numerous studies, it remains unclear whether NSC accumulation or N deficiency more directly decreases steady-state maximum photosynthesis and photosynthetic induction, as well as underlying gene expression profiles. We evaluated the relationship between photosynthetic capacity and NSC accumulation induced by cold girdling, sucrose feeding, and low nitrogen treatment in Glycine max and Phaseolus vulgaris. In G. max, changes in transcriptome profiles were further investigated, focusing on the physiological processes of photosynthesis and NSC accumulation. NSC accumulation decreased the maximum photosynthetic capacity and delayed photosynthetic induction in both species. In G. max, such photosynthetic downregulation was explained by coordinated downregulation of photosynthetic genes involved in the Calvin cycle, Rubisco activase, photochemical reactions, and stomatal opening. Furthermore, sink-source imbalance may have triggered a change in the balance of sugar-phosphate translocators in chloroplast membranes, which may have promoted starch accumulation in chloroplasts. Our findings provide an overall picture of photosynthetic downregulation and NSC accumulation in G. max, demonstrating that photosynthetic downregulation is triggered by NSC accumulation and cannot be explained solely by N deficiency.
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Affiliation(s)
- Yui Ozawa
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Aiko Tanaka
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Takamasa Suzuki
- College of Bioscience and Biotechnology, Chubu University, Kasugai, Aichi, Japan
| | - Daisuke Sugiura
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
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Wang JW, Squire HJ, Goh NS, Ni HM, Lien E, Wong C, González-Grandío E, Landry MP. Delivered complementation in planta (DCIP) enables measurement of peptide-mediated protein delivery efficiency in plants. Commun Biol 2023; 6:840. [PMID: 37573467 PMCID: PMC10423278 DOI: 10.1038/s42003-023-05191-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Accepted: 07/28/2023] [Indexed: 08/14/2023] Open
Abstract
Using a fluorescence complementation assay, Delivered Complementation in Planta (DCIP), we demonstrate cell-penetrating peptide-mediated cytosolic delivery of peptides and recombinant proteins in Nicotiana benthamiana. We show that DCIP enables quantitative measurement of protein delivery efficiency and enables functional screening of cell-penetrating peptides for in-planta protein delivery. Finally, we demonstrate that DCIP detects cell-penetrating peptide-mediated delivery of recombinantly expressed proteins such as mCherry and Lifeact into intact leaves. We also demonstrate delivery of a recombinant plant transcription factor, WUSCHEL (AtWUS), into N. benthamiana. RT-qPCR analysis of AtWUS delivery in Arabidopsis seedlings also suggests delivered WUS can recapitulate transcriptional changes induced by overexpression of AtWUS. Taken together, our findings demonstrate that DCIP offers a new and powerful tool for interrogating cytosolic delivery of proteins in plants and highlights future avenues for engineering plant physiology.
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Affiliation(s)
- Jeffrey W Wang
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Henry J Squire
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Natalie S Goh
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Heyuan Michael Ni
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Edward Lien
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Cerise Wong
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Eduardo González-Grandío
- Plant Molecular Genetics Department, Centro Nacional de Biotecnología-CSIC, Campus Universidad Autónoma de Madrid, Madrid, Spain
| | - Markita P Landry
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA, 94720, USA.
- Innovative Genomics Institute, Berkeley, CA, 94720, USA.
- California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA, 94720, USA.
- Chan Zuckerberg Biohub, San Francisco, CA, 94063, USA.
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Xiong D. Leaf anatomy does not explain the large variability of mesophyll conductance across C 3 crop species. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2023; 113:1035-1048. [PMID: 36602006 DOI: 10.1111/tpj.16098] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2022] [Revised: 12/29/2022] [Accepted: 01/02/2023] [Indexed: 06/17/2023]
Abstract
Increasing mesophyll conductance of CO2 (gm ) is a strategy to improve photosynthesis in C3 crops. However, the relative importance of different anatomical traits in determining gm in crops is unclear. Mesophyll conductance measurements were performed on 10 crops using the online carbon isotope discrimination method and the 'variable J' method in parallel. The influences of crucial leaf anatomical traits on gm were evaluated using a one-dimensional anatomical CO2 diffusion model. The gm values measured using two independent methods were compatible, although significant differences were observed in their absolute values. Quantitative analysis showed that cell wall thickness and chloroplast stroma thickness are the most important elements along the diffusion pathway. Unexpectedly, the large variability of gm across crops was not associated with any investigated leaf anatomical traits except chloroplast thickness. The gm values estimated using the anatomical model differed remarkably from the values measured in vivo in most species. However, when the species-specific effective porosity of the cell wall and the species-specific facilitation effect of CO2 diffusion across the membrane and chloroplast stoma were taken into account, the model could output gm values very similar to those measured in vivo. These results indicate that gm variation across crops is probably also driven by the effective porosity of the cell wall and effects of facilitation of CO2 transport across the membrane and chloroplast stroma in addition to the thicknesses of the elements.
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Affiliation(s)
- Dongliang Xiong
- National Key Laboratory of Crop Genetic Improvement, Hubei Hongshan Laboratory, MOA Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
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Ouk R, Oi T, Sugiura D, Taniguchi M. 3-D reconstruction of rice leaf tissue for proper estimation of surface area of mesophyll cells and chloroplasts facing intercellular airspaces from 2-D section images. ANNALS OF BOTANY 2022; 130:991-998. [PMID: 36283030 PMCID: PMC9851327 DOI: 10.1093/aob/mcac133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Accepted: 10/24/2022] [Indexed: 06/16/2023]
Abstract
BACKGROUND AND AIMS The surface area of mesophyll cells (Smes) and chloroplasts (Sc) facing the intercellular airspace (IAS) are important parameters for estimating photosynthetic activity from leaf anatomy. Although Smes and Sc are estimated based on the shape assumption of mesophyll cells (MCs), it is questionable if the assumption is correct for rice MCs with concave-convex surfaces. Therefore, in this study, we establish a reconstruction method for the 3-D representation of the IAS in rice leaf tissue to calculate the actual Smes and Sc with 3-D images and to determine the correct shape assumption for the estimation of Smes and Sc based on 2-D section images. METHODS We used serial section light microscopy to reconstruct 3-D representations of the IAS, MCs and chloroplasts in rice leaf tissue. Actual Smes and Sc values obtained from the 3-D representation were compared with those estimated from the 2-D images to find the correct shape-specific assumption (oblate or prolate spheroid) in different orientations (longitudinal and transverse sections) using the same leaf sample. KEY RESULTS The 3-D representation method revealed that volumes of the IAS and MCs accounted for 30 and 70 % of rice leaf tissue excluding epidermis, respectively, and the volume of chloroplasts accounted for 44 % of MCs. The shape-specific assumption on the sectioning orientation affected the estimation of Smes and Sc using 2-D section images with discrepancies of 10-38 %. CONCLUSIONS The 3-D representation of rice leaf tissue was successfully reconstructed using serial section light microscopy and suggested that estimation of Smes and Sc of the rice leaf is more accurate using longitudinal sections with MCs assumed as oblate spheroids than using transverse sections with MCs as prolate spheroids.
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Affiliation(s)
- Rachana Ouk
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Takao Oi
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Daisuke Sugiura
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Mitsutaka Taniguchi
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
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Alonso-Forn D, Peguero-Pina JJ, Ferrio JP, García-Plazaola JI, Martín-Sánchez R, Niinemets Ü, Sancho-Knapik D, Gil-Pelegrín E. Cell-level anatomy explains leaf age-dependent declines in mesophyll conductance and photosynthetic capacity in the evergreen Mediterranean oak Quercus ilex subsp. rotundifolia. TREE PHYSIOLOGY 2022; 42:1988-2002. [PMID: 35451029 DOI: 10.1093/treephys/tpac049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 04/13/2022] [Indexed: 06/14/2023]
Abstract
Leaves of Mediterranean evergreen tree species experience a reduction in net CO2 assimilation (AN) and mesophyll conductance to CO2 (gm) during aging and senescence, which would be influenced by changes in leaf anatomical traits at cell level. Anatomical modifications can be accompanied by the dismantling of photosynthetic apparatus associated to leaf senescence, manifested through changes at the biochemical level (i.e., lower nitrogen investment in photosynthetic machinery). However, the role of changes in leaf anatomy at cell level and nitrogen content in gm and AN decline experienced by old non-senescent leaves of evergreen trees with long leaf lifespan is far from being elucidated. We evaluated age-dependent changes in morphological, anatomical, chemical and photosynthetic traits in Quercus ilex subsp. rotundifolia Lam., an evergreen oak with high leaf longevity. All photosynthetic traits decreased with increasing leaf age. The relative change in cell wall thickness (Tcw) was less than in chloroplast surface area exposed to intercellular air space (Sc/S), and Sc/S was a key anatomical trait explaining variations in gm and AN among different age classes. The reduction of Sc/S was related to ultrastructural changes in chloroplasts associated to leaf aging, with a concomitant reduction in cytoplasmic nitrogen. Changes in leaf anatomy and biochemistry were responsible for the age-dependent modifications in gm and AN. These findings revealed a gradual physiological deterioration related to the dismantling of the photosynthetic apparatus in older leaves of Q. ilex subsp. rotundifolia.
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Affiliation(s)
- David Alonso-Forn
- Departamento de Sistemas Agrícolas, Forestales y Medio Ambiente, Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA), Avda Montañana 930, Zaragoza 50059, Spain
| | - José Javier Peguero-Pina
- Departamento de Sistemas Agrícolas, Forestales y Medio Ambiente, Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA), Avda Montañana 930, Zaragoza 50059, Spain
- Instituto Agroalimentario de Aragón -IA2- (CITA-Universidad de Zaragoza), Zaragoza, Spain
| | - Juan Pedro Ferrio
- Departamento de Sistemas Agrícolas, Forestales y Medio Ambiente, Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA), Avda Montañana 930, Zaragoza 50059, Spain
- Aragon Agency for Research and Development (ARAID), Zaragoza E-50018, Spain
| | - José Ignacio García-Plazaola
- Department of Plant Biology and Ecology, University of the Basque Country (UPV/EHU), Apdo 644, Bilbao 48080, Spain
| | - Rubén Martín-Sánchez
- Departamento de Sistemas Agrícolas, Forestales y Medio Ambiente, Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA), Avda Montañana 930, Zaragoza 50059, Spain
| | - Ülo Niinemets
- Crop Science and Plant Biology, Estonian University of Life Sciences, Kreutzwaldi 1, 51006 Tartu, Estonia
| | - Domingo Sancho-Knapik
- Departamento de Sistemas Agrícolas, Forestales y Medio Ambiente, Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA), Avda Montañana 930, Zaragoza 50059, Spain
- Instituto Agroalimentario de Aragón -IA2- (CITA-Universidad de Zaragoza), Zaragoza, Spain
| | - Eustaquio Gil-Pelegrín
- Departamento de Sistemas Agrícolas, Forestales y Medio Ambiente, Centro de Investigación y Tecnología Agroalimentaria de Aragón (CITA), Avda Montañana 930, Zaragoza 50059, Spain
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Mizokami Y, Oguchi R, Sugiura D, Yamori W, Noguchi K, Terashima I. Cost-benefit analysis of mesophyll conductance: diversities of anatomical, biochemical and environmental determinants. ANNALS OF BOTANY 2022; 130:265-283. [PMID: 35947983 PMCID: PMC9487971 DOI: 10.1093/aob/mcac100] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Accepted: 08/08/2022] [Indexed: 06/09/2023]
Abstract
BACKGROUND Plants invest photosynthates in construction and maintenance of their structures and functions. Such investments are considered costs. These costs are recovered by the CO2 assimilation rate (A) in the leaves, and thus A is regarded as the immediate, short-term benefit. In photosynthesizing leaves, CO2 diffusion from the air to the carboxylation site is hindered by several structural and biochemical barriers. CO2 diffusion from the intercellular air space to the chloroplast stroma is obstructed by the mesophyll resistance. The inverses is the mesophyll conductance (gm). Whether various plants realize an optimal gm, and how much investment is needed for a relevant gm, remain unsolved. SCOPE This review examines relationships among leaf construction costs (CC), leaf maintenance costs (MC) and gm in various plants under diverse growth conditions. Through a literature survey, we demonstrate a strong linear relationship between leaf mass per area (LMA) and leaf CC. The overall correlation of CC vs. gm across plant phylogenetic groups is weak, but significant trends are evident within specific groups and/or environments. Investment in CC is necessary for an increase in LMA and mesophyll cell surface area (Smes). This allows the leaf to accommodate more chloroplasts, thus increasing A. However, increases in LMA and/or Smes often accompany other changes, such as cell wall thickening, which diminishes gm. Such factors that make the correlations of CC and gm elusive are identified. CONCLUSIONS For evaluation of the contribution of gm to recover CC, leaf life span is the key factor. The estimation of MC in relation to gm, especially in terms of costs required to regulate aquaporins, could be essential for efficient control of gm over the short term. Over the long term, costs are mainly reflected in CC, while benefits also include ultimate fitness attributes in terms of integrated carbon gain over the life of a leaf, plant survival and reproductive output.
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Affiliation(s)
- Yusuke Mizokami
- Department of Life Science, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan
| | - Riichi Oguchi
- Department of Biological Sciences, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Daisuke Sugiura
- Graduate School of Bioagricultural Sciences, Nagoya University, Furo, Chikusa-ku, Nagoya 464-8601, Japan
| | - Wataru Yamori
- Graduate School of Agricultural and Life Science, Institute for Sustainable Agri-ecosystem, The University of Tokyo, 1-1-1, Midoricho, Nishitokyo, Tokyo 188-0002, Japan
| | - Ko Noguchi
- Department of Life Science, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan
| | - Ichiro Terashima
- Department of Biological Sciences, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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Joffe R, Berthe A, Jolivet Y, Gandin A. The response of mesophyll conductance to ozone-induced oxidative stress is genotype-dependent in poplar. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:4850-4866. [PMID: 35429268 DOI: 10.1093/jxb/erac154] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Accepted: 04/14/2022] [Indexed: 06/14/2023]
Abstract
The CO2 diffusion conductance within the leaf mesophyll (gm) is considered a major limiting factor of photosynthesis. However, the effects of the major secondary air pollutant ozone (O3) on gm have been poorly investigated. Eight genotypes of the economically important tree species Populus × canadensis Moench were exposed to 120 ppb O3 for 21 d. gm showed a genotype-dependent response to O3-induced oxidative stress and was a major limiting factor of net assimilation rate (Anet), ahead of stomatal conductance to CO2 (gsc) and of the maximum carboxylation capacity of the Rubisco enzyme (Vcmax) in half of the tested genotypes. Increased leaf dry mass per area (LMA) and decreased chlorophyll content were linked to the observed gm decrease, but this relationship did not entirely explain the different genotypic gm responses. Moreover, the oxidative stress defence metabolites ascorbate and glutathione were not related to O3 tolerance of gm. However, malondialdehyde probably mitigated the observed gm decrease in some genotypes due to its oxidative stress signalling function. The large variation of gm suggests different regulation mechanisms amongst poplar genotypes under oxidative stress.
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Affiliation(s)
- Ricardo Joffe
- Université de Lorraine, AgroParisTech, INRAE, SILVA, F-54000 Nancy, France
| | - Audrey Berthe
- Université de Lorraine, AgroParisTech, INRAE, SILVA, F-54000 Nancy, France
| | - Yves Jolivet
- Université de Lorraine, AgroParisTech, INRAE, SILVA, F-54000 Nancy, France
| | - Anthony Gandin
- Université de Lorraine, AgroParisTech, INRAE, SILVA, F-54000 Nancy, France
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Ozeki K, Miyazawa Y, Sugiura D. Rapid stomatal closure contributes to higher water use efficiency in major C4 compared to C3 Poaceae crops. PLANT PHYSIOLOGY 2022; 189:188-203. [PMID: 35134220 PMCID: PMC9070804 DOI: 10.1093/plphys/kiac040] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Accepted: 12/08/2021] [Indexed: 06/02/2023]
Abstract
Understanding water use characteristics of C3 and C4 crops is important for food security under climate change. Here, we aimed to clarify how stomatal dynamics and water use efficiency (WUE) differ in fluctuating environments in major C3 and C4 crops. Under high and low nitrogen conditions, we evaluated stomatal morphology and kinetics of stomatal conductance (gs) at leaf and whole-plant levels in controlled fluctuating light environments in four C3 and five C4 Poaceae species. We developed a dynamic photosynthesis model, which incorporates C3 and C4 photosynthesis models that consider stomatal dynamics, to evaluate the contribution of rapid stomatal opening and closing to photosynthesis and WUE. C4 crops showed more rapid stomatal opening and closure than C3 crops, which could be explained by smaller stomatal size and higher stomatal density in plants grown at high nitrogen conditions. Our model analysis indicated that accelerating the speed of stomatal closure in C3 crops to the level of C4 crops could enhance WUE up to 16% by reducing unnecessary water loss during low light periods, whereas accelerating stomatal opening only minimally enhanced photosynthesis. The present results suggest that accelerating the speed of stomatal closure in major C3 crops to the level of major C4 crops is a potential breeding target for the realization of water-saving agriculture.
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Affiliation(s)
- Kengo Ozeki
- Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya 464-8601, Japan
| | - Yoshiyuki Miyazawa
- Campus Planning Office, Kyushu University, Nishi, Fukuoka 819-0395, Japan
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12
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Wei X, Yang Y, Yao J, Han J, Yan M, Zhang J, Shi Y, Wang J, Mu C. Improved Utilization of Nitrate Nitrogen Through Within-Leaf Nitrogen Allocation Trade-Offs in Leymus chinensis. FRONTIERS IN PLANT SCIENCE 2022; 13:870681. [PMID: 35574094 PMCID: PMC9096725 DOI: 10.3389/fpls.2022.870681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Accepted: 03/21/2022] [Indexed: 06/15/2023]
Abstract
The Sharply increasing atmospheric nitrogen (N) deposition may substantially impact the N availability and photosynthetic capacity of terrestrial plants. Determining the trade-off relationship between within-leaf N sources and allocation is therefore critical for understanding the photosynthetic response to nitrogen deposition in grassland ecosystems. We conducted field experiments to examine the effects of inorganic nitrogen addition (sole NH4 +, sole NO3 - and mixed NH4 +/NO3 -: 50%/50%) on N assimilation and allocation by Leymus chinensis. The leaf N allocated to the photosynthetic apparatus (NPSN) and chlorophyll content per unit area (Chlarea) were significantly positively correlated with the photosynthetic N-use efficiency (PNUE). The sole NO3 - treatment significantly increased the plant leaf PNUE and biomass by increasing the photosynthetic N allocation and Chlarea. Under the NO3 treatment, L. chinensis plants devoted more N to their bioenergetics and light-harvesting systems to increase electron transfer. Plants reduced the cell wall N allocation or increased their soluble protein concentrations to balance growth and defense under the NO3 treatment. In the sole NH4 + treatment, however, plants decreased their N allocation to photosynthetic components, but increased their N allocation to the cell wall and elsewhere. Our findings demonstrated that within-leaf N allocation optimization is a key adaptive mechanism by which plants maximize their PNUE and biomass under predicted future global changes.
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Affiliation(s)
- Xiaowei Wei
- Key Laboratory of Vegetation Ecology of the Ministry of Education, Jilin Songnen Grassland Ecosystem National Observation and Research Station, Institute of Grassland Science, Northeast Normal University, Changchun, China
- Key Laboratory for Plant Resources Science and Green Production, Jilin Normal University, Siping, China
| | - Yuheng Yang
- Key Laboratory of Vegetation Ecology of the Ministry of Education, Jilin Songnen Grassland Ecosystem National Observation and Research Station, Institute of Grassland Science, Northeast Normal University, Changchun, China
| | - Jialiang Yao
- Key Laboratory of Vegetation Ecology of the Ministry of Education, Jilin Songnen Grassland Ecosystem National Observation and Research Station, Institute of Grassland Science, Northeast Normal University, Changchun, China
| | - Jiayu Han
- Key Laboratory of Vegetation Ecology of the Ministry of Education, Jilin Songnen Grassland Ecosystem National Observation and Research Station, Institute of Grassland Science, Northeast Normal University, Changchun, China
| | - Ming Yan
- Key Laboratory of Vegetation Ecology of the Ministry of Education, Jilin Songnen Grassland Ecosystem National Observation and Research Station, Institute of Grassland Science, Northeast Normal University, Changchun, China
| | - Jinwei Zhang
- Key Laboratory of Vegetation Ecology of the Ministry of Education, Jilin Songnen Grassland Ecosystem National Observation and Research Station, Institute of Grassland Science, Northeast Normal University, Changchun, China
| | - Yujie Shi
- Key Laboratory of Vegetation Ecology of the Ministry of Education, Jilin Songnen Grassland Ecosystem National Observation and Research Station, Institute of Grassland Science, Northeast Normal University, Changchun, China
| | - Junfeng Wang
- Key Laboratory of Vegetation Ecology of the Ministry of Education, Jilin Songnen Grassland Ecosystem National Observation and Research Station, Institute of Grassland Science, Northeast Normal University, Changchun, China
| | - Chunsheng Mu
- Key Laboratory of Vegetation Ecology of the Ministry of Education, Jilin Songnen Grassland Ecosystem National Observation and Research Station, Institute of Grassland Science, Northeast Normal University, Changchun, China
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13
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Huang G, Shu Y, Peng S, Li Y. Leaf photosynthesis is positively correlated with xylem and phloem areas in leaf veins in rice (Oryza sativa) plants. ANNALS OF BOTANY 2022; 129:619-631. [PMID: 35143609 PMCID: PMC9007091 DOI: 10.1093/aob/mcac020] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 02/09/2022] [Indexed: 05/23/2023]
Abstract
BACKGROUND AND AIMS Leaf structure is an important determinant of leaf photosynthesis; however, the impacts of leaf structural traits on gas exchange parameters are still not fully understood. In the present study, 11 rice genotypes were grown in pots to investigate the influence of leaf structural traits on leaf photosynthesis and hydraulic conductance (Kleaf). METHODS In this study, leaf photosynthetic rate (A), stomatal conductance (gs), mesophyll conductance and Kleaf were measured. In addition, leaf structural traits including leaf thickness (LT), leaf mass per area and leaf xylem and phloem sizes were also measured to investigate their impacts on rice photosynthesis. KEY RESULTS We found that the total area of xylem conduits per major vein (Xmajor), leaf phloem area per minor vein (Pminor) and LT were positively correlated with Kleaf, gs and A. The path analysis suggested that, however, only Pminor had a direct impact on A; Xmajor had an indirect impact on A via gs and Pminor, while LT did not show any direct or indirect impact on A. CONCLUSION This study highlighted the importance of manipulations in Xmajor and Pminor, two previously overlooked leaf traits, to improve leaf photosynthesis in rice plants.
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Affiliation(s)
- Guanjun Huang
- National Key Laboratory of Crop Genetic Improvement, Ministry of Agriculture Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Yu Shu
- National Key Laboratory of Crop Genetic Improvement, Ministry of Agriculture Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Shaobing Peng
- National Key Laboratory of Crop Genetic Improvement, Ministry of Agriculture Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Yong Li
- National Key Laboratory of Crop Genetic Improvement, Ministry of Agriculture Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China
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14
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Khoshravesh R, Hoffmann N, Hanson DT. Leaf microscopy applications in photosynthesis research: identifying the gaps. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:1868-1893. [PMID: 34986250 DOI: 10.1093/jxb/erab548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [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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15
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Nadal-Sala D, Grote R, Birami B, Knüver T, Rehschuh R, Schwarz S, Ruehr NK. Leaf Shedding and Non-Stomatal Limitations of Photosynthesis Mitigate Hydraulic Conductance Losses in Scots Pine Saplings During Severe Drought Stress. FRONTIERS IN PLANT SCIENCE 2021; 12:715127. [PMID: 34539705 PMCID: PMC8448192 DOI: 10.3389/fpls.2021.715127] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Accepted: 07/08/2021] [Indexed: 06/01/2023]
Abstract
During drought, trees reduce water loss and hydraulic failure by closing their stomata, which also limits photosynthesis. Under severe drought stress, other acclimation mechanisms are trigged to further reduce transpiration to prevent irreversible conductance loss. Here, we investigate two of them: the reversible impacts on the photosynthetic apparatus, lumped as non-stomatal limitations (NSL) of photosynthesis, and the irreversible effect of premature leaf shedding. We integrate NSL and leaf shedding with a state-of-the-art tree hydraulic simulation model (SOX+) and parameterize them with example field measurements to demonstrate the stress-mitigating impact of these processes. We measured xylem vulnerability, transpiration, and leaf litter fall dynamics in Pinus sylvestris (L.) saplings grown for 54 days under severe dry-down. The observations showed that, once transpiration stopped, the rate of leaf shedding strongly increased until about 30% of leaf area was lost on average. We trained the SOX+ model with the observations and simulated changes in root-to-canopy conductance with and without including NSL and leaf shedding. Accounting for NSL improved model representation of transpiration, while model projections about root-to-canopy conductance loss were reduced by an overall 6%. Together, NSL and observed leaf shedding reduced projected losses in conductance by about 13%. In summary, the results highlight the importance of other than purely stomatal conductance-driven adjustments of drought resistance in Scots pine. Accounting for acclimation responses to drought, such as morphological (leaf shedding) and physiological (NSL) adjustments, has the potential to improve tree hydraulic simulation models, particularly when applied in predicting drought-induced tree mortality.
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Affiliation(s)
- Daniel Nadal-Sala
- Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research - Atmospheric Environmental Research (IMK-IFU), Garmisch-Partenkirchen, Germany
| | - Rüdiger Grote
- Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research - Atmospheric Environmental Research (IMK-IFU), Garmisch-Partenkirchen, Germany
| | - Benjamin Birami
- Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research - Atmospheric Environmental Research (IMK-IFU), Garmisch-Partenkirchen, Germany
- University of Bayreuth, Chair of Plant Ecology, Bayreuth, Germany
| | - Timo Knüver
- Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research - Atmospheric Environmental Research (IMK-IFU), Garmisch-Partenkirchen, Germany
- Department of Botany, University of Innsbruck, Innsbruck, Austria
| | - Romy Rehschuh
- Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research - Atmospheric Environmental Research (IMK-IFU), Garmisch-Partenkirchen, Germany
| | - Selina Schwarz
- Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research - Atmospheric Environmental Research (IMK-IFU), Garmisch-Partenkirchen, Germany
| | - Nadine K. Ruehr
- Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research - Atmospheric Environmental Research (IMK-IFU), Garmisch-Partenkirchen, Germany
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16
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Carriquí M, Nadal M, Flexas J. Acclimation of mesophyll conductance and anatomy to light during leaf aging in Arabidopsis thaliana. PHYSIOLOGIA PLANTARUM 2021; 172:1894-1907. [PMID: 33724455 DOI: 10.1111/ppl.13398] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 03/04/2021] [Accepted: 03/10/2021] [Indexed: 06/12/2023]
Abstract
Mesophyll conductance (gm ), a key limitation to photosynthesis, is strongly driven by leaf anatomy, which is in turn influenced by environmental growth conditions and ontogeny. However, studies examining the combined environment × age effect on both leaf anatomy and photosynthesis are scarce, and none have been carried out in short-lived plants. Here, we studied the variation of photosynthesis and leaf anatomy in the model species Arabidopsis thaliana (Col-0) grown under three different light intensities at two different leaf ages. We found that light × age interaction was significant for photosynthesis but not for anatomical characteristics. Increasing growth light intensities resulted in increases in leaf mass per area, thickness, number of palisade cell layers, and chloroplast area lining to intercellular airspace. Low and moderate-but not high-light intensity had a significant effect on all photosynthetic characteristics. Leaf aging was associated with increases in cell wall thickness (Tcw ) in all light treatments and in increases in leaf thickness in plants grown under low and moderate light intensities. However, gm did not vary with leaf aging, and photosynthesis only decreased with leaf age under moderate and high light, suggesting a compensatory effect between increased Tcw and decreased chloroplast thickness on the total CO2 diffusion resistance.
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Affiliation(s)
- Marc Carriquí
- School of Natural Sciences, University of Tasmania, Hobart, Tasmania, Australia
- Research Group in Plant Biology under Mediterranean Conditions, Universitat de les Illes Balears, Palma, Spain
| | - Miquel Nadal
- Research Group in Plant Biology under Mediterranean Conditions, Universitat de les Illes Balears, Palma, Spain
| | - Jaume Flexas
- Research Group in Plant Biology under Mediterranean Conditions, Universitat de les Illes Balears, Palma, Spain
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17
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Flexas J, Clemente-Moreno MJ, Bota J, Brodribb TJ, Gago J, Mizokami Y, Nadal M, Perera-Castro AV, Roig-Oliver M, Sugiura D, Xiong D, Carriquí M. Cell wall thickness and composition are involved in photosynthetic limitation. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:3971-3986. [PMID: 33780533 DOI: 10.1093/jxb/erab144] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Accepted: 03/25/2021] [Indexed: 06/12/2023]
Abstract
The key role of cell walls in setting mesophyll conductance to CO2 (gm) and, consequently, photosynthesis is reviewed. First, the theoretical properties of cell walls that can affect gm are presented. Then, we focus on cell wall thickness (Tcw) reviewing empirical evidence showing that Tcw varies strongly among species and phylogenetic groups in a way that correlates with gm and photosynthesis; that is, the thicker the mesophyll cell walls, the lower the gm and photosynthesis. Potential interplays of gm, Tcw, dehydration tolerance, and hydraulic properties of leaves are also discussed. Dynamic variations of Tcw in response to the environment and their implications in the regulation of photosynthesis are discussed, and recent evidence suggesting an influence of cell wall composition on gm is presented. We then propose a hypothetical mechanism for the influence of cell walls on photosynthesis, combining the effects of thickness and composition, particularly pectins. Finally, we discuss the prospects for using biotechnology for enhancing photosynthesis by altering cell wall-related genes.
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Affiliation(s)
- Jaume Flexas
- Research Group on Plant Biology under Mediterranean Conditions, Institut d'Investigacions Agroambientals i d'Economia de l'Aigua (INAGEA) - Universitat de les Illes Balears (UIB), Ctra Valldemossa Km 7.5., 07122, Palma, Illes Balears, Spain
| | - María J Clemente-Moreno
- Research Group on Plant Biology under Mediterranean Conditions, Institut d'Investigacions Agroambientals i d'Economia de l'Aigua (INAGEA) - Universitat de les Illes Balears (UIB), Ctra Valldemossa Km 7.5., 07122, Palma, Illes Balears, Spain
| | - Josefina Bota
- Research Group on Plant Biology under Mediterranean Conditions, Institut d'Investigacions Agroambientals i d'Economia de l'Aigua (INAGEA) - Universitat de les Illes Balears (UIB), Ctra Valldemossa Km 7.5., 07122, Palma, Illes Balears, Spain
| | - Tim J Brodribb
- School of Biological Sciences, University of Tasmania, Hobart, TAS, Australia
| | - Jorge Gago
- Research Group on Plant Biology under Mediterranean Conditions, Institut d'Investigacions Agroambientals i d'Economia de l'Aigua (INAGEA) - Universitat de les Illes Balears (UIB), Ctra Valldemossa Km 7.5., 07122, Palma, Illes Balears, Spain
| | - Yusuke Mizokami
- Laboratory of Applied Ecology, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji-shi, Tokyo, Japan
| | - Miquel Nadal
- Research Group on Plant Biology under Mediterranean Conditions, Institut d'Investigacions Agroambientals i d'Economia de l'Aigua (INAGEA) - Universitat de les Illes Balears (UIB), Ctra Valldemossa Km 7.5., 07122, Palma, Illes Balears, Spain
| | - Alicia V Perera-Castro
- Research Group on Plant Biology under Mediterranean Conditions, Institut d'Investigacions Agroambientals i d'Economia de l'Aigua (INAGEA) - Universitat de les Illes Balears (UIB), Ctra Valldemossa Km 7.5., 07122, Palma, Illes Balears, Spain
| | - Margalida Roig-Oliver
- Research Group on Plant Biology under Mediterranean Conditions, Institut d'Investigacions Agroambientals i d'Economia de l'Aigua (INAGEA) - Universitat de les Illes Balears (UIB), Ctra Valldemossa Km 7.5., 07122, Palma, Illes Balears, Spain
| | - Daisuke Sugiura
- Laboratory of Crop Science, Department of Plant Production Sciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, Japan
| | - Dongliang Xiong
- National Key Laboratory of Crop Genetic Improvement, MOA Key Laboratory of Crop Ecophysiology and Farming System in the Middle Reaches of the Yangtze River, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Marc Carriquí
- School of Biological Sciences, University of Tasmania, Hobart, TAS, Australia
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18
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Clarke VC, Danila FR, von Caemmerer S. CO 2 diffusion in tobacco: a link between mesophyll conductance and leaf anatomy. Interface Focus 2021; 11:20200040. [PMID: 33628426 PMCID: PMC7898150 DOI: 10.1098/rsfs.2020.0040] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/09/2020] [Indexed: 12/28/2022] Open
Abstract
The partial pressure of CO2 at the sites of carboxylation within chloroplasts depends on the conductance to CO2 diffusion from intercellular airspace to the sites of carboxylation, termed mesophyll conductance (gm). We investigated how gm varies with leaf age and through a tobacco (Nicotiana tabacum) canopy by combining gas exchange and carbon isotope measurements using tunable diode laser spectroscopy. We combined these measurements with the anatomical characterization of leaves. CO2 assimilation rate, A, and gm decreased as leaves aged and moved lower in the canopy and were linearly correlated. This was accompanied by large anatomical changes including an increase in leaf thickness. Chloroplast surface area exposed to the intercellular airspace per unit leaf area (Sc) also decreased lower in the canopy. Older leaves had thicker mesophyll cell walls and gm was inversely proportional to cell wall thickness. We conclude that reduced gm of older leaves lower in the canopy was associated with a reduction in Sc and a thickening of mesophyll cell walls.
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Affiliation(s)
- Victoria C Clarke
- Australian Research Council Centre of Excellence for Translational Photosynthesis, Division of Plant Science, Research School of Biology, The Australian National University, Acton, Australian Capital Territory 2601, Australia
| | - Florence R Danila
- Australian Research Council Centre of Excellence for Translational Photosynthesis, Division of Plant Science, Research School of Biology, The Australian National University, Acton, Australian Capital Territory 2601, Australia
| | - Susanne von Caemmerer
- Australian Research Council Centre of Excellence for Translational Photosynthesis, Division of Plant Science, Research School of Biology, The Australian National University, Acton, Australian Capital Territory 2601, Australia
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19
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Cooney LJ, Beechey-Gradwell Z, Winichayakul S, Richardson KA, Crowther T, Anderson P, Scott RW, Bryan G, Roberts NJ. Changes in Leaf-Level Nitrogen Partitioning and Mesophyll Conductance Deliver Increased Photosynthesis for Lolium perenne Leaves Engineered to Accumulate Lipid Carbon Sinks. FRONTIERS IN PLANT SCIENCE 2021; 12:641822. [PMID: 33897730 PMCID: PMC8063613 DOI: 10.3389/fpls.2021.641822] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 02/11/2021] [Indexed: 06/12/2023]
Abstract
Diacylglycerol acyl-transferase (DGAT) and cysteine oleosin (CO) expression confers a novel carbon sink (of encapsulated lipid droplets) in leaves of Lolium perenne and has been shown to increase photosynthesis and biomass. However, the physiological mechanism by which DGAT + CO increases photosynthesis remains unresolved. To evaluate the relationship between sink strength and photosynthesis, we examined fatty acids (FA), water-soluble carbohydrates (WSC), gas exchange parameters and leaf nitrogen for multiple DGAT + CO lines varying in transgene accumulation. To identify the physiological traits which deliver increased photosynthesis, we assessed two important determinants of photosynthetic efficiency, CO2 conductance from atmosphere to chloroplast, and nitrogen partitioning between different photosynthetic and non-photosynthetic pools. We found that DGAT + CO accumulation increased FA at the expense of WSC in leaves of L. perenne and for those lines with a significant reduction in WSC, we also observed an increase in photosynthesis and photosynthetic nitrogen use efficiency. DGAT + CO L. perenne displayed no change in rubisco content or Vcmax but did exhibit a significant increase in specific leaf area (SLA), stomatal and mesophyll conductance, and leaf nitrogen allocated to photosynthetic electron transport. Collectively, we showed that increased carbon demand via DGAT+CO lipid sink accumulation can induce leaf-level changes in L. perenne which deliver increased rates of photosynthesis and growth. Carbon sinks engineered within photosynthetic cells provide a promising new strategy for increasing photosynthesis and crop productivity.
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20
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Evans JR. Mesophyll conductance: walls, membranes and spatial complexity. THE NEW PHYTOLOGIST 2021; 229:1864-1876. [PMID: 33135193 DOI: 10.1111/nph.16968] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 08/28/2020] [Indexed: 06/11/2023]
Abstract
A significant resistance to CO2 diffusion is imposed by mesophyll tissue inside leaves. Mesophyll resistance, rm (or its reciprocal, mesophyll conductance, gm ), reduces the rate at which Rubisco can fix CO2 , increasing the water and nitrogen costs of carbon acquisition. gm varies in proportion to the surface area of chloroplasts exposed to intercellular airspace per unit leaf area. It also depends on the thickness and effective porosity of the cell wall and the CO2 permeabilities of membranes. As no measurements exist for the effective porosity of mesophyll cell walls, and CO2 permeability values are too low to account for observed rates of CO2 assimilation, conclusions from modelling must be treated with caution. There is great variation in the mesophyll resistance per unit chloroplast area for a given cell wall thickness, which may reflect differences in effective porosity. While apparent gm can vary with CO2 and irradiance, the underlying conductance at the cellular level may remain unchanged. Dynamic changes in apparent gm arise for spatial reasons and because chloroplasts differ in their photosynthetic composition and operate in different light environments. Measurements of the temperature sensitivity of membrane CO2 permeability are urgently needed to explain variation in temperature responses of gm .
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Affiliation(s)
- John R Evans
- ARC Centre of Excellence for Translational Photosynthesis, Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
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