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Pathare VS, DiMario RJ, Koteyeva N, Cousins AB. Mesophyll conductance response to short-term changes in pCO 2 is related to leaf anatomy and biochemistry in diverse C 4 grasses. New Phytol 2022; 236:1281-1295. [PMID: 35959528 PMCID: PMC9825963 DOI: 10.1111/nph.18427] [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] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 07/31/2022] [Indexed: 06/15/2023]
Abstract
Mesophyll CO2 conductance (gm ) in C3 species responds to short-term (minutes) changes in environment potentially due to changes in leaf anatomical and biochemical properties and measurement artefacts. Compared with C3 species, there is less information on gm responses to short-term changes in environmental conditions such as partial pressure of CO2 (pCO2 ) across diverse C4 species and the potential determinants of these responses. Using 16 C4 grasses we investigated the response of gm to short-term changes in pCO2 and its relationship with leaf anatomy and biochemistry. In general, gm increased as pCO2 decreased (statistically significant increase in 12 species), with percentage increases in gm ranging from +13% to +250%. Greater increase in gm at low pCO2 was observed in species exhibiting relatively thinner mesophyll cell walls along with greater mesophyll surface area exposed to intercellular air spaces, leaf N, photosynthetic capacity and activities of phosphoenolpyruvate carboxylase and Rubisco. Species with greater CO2 responses of gm were also able to maintain their leaf water-use efficiencies (TEi ) under low CO2 . Our study advances understanding of CO2 response of gm in diverse C4 species, identifies the key leaf traits related to this response and has implications for improving C4 photosynthetic models and TEi through modification of gm .
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Affiliation(s)
- Varsha S. Pathare
- School of Biological SciencesWashington State UniversityPullmanWA99164‐4236USA
| | - Robert J. DiMario
- School of Biological SciencesWashington State UniversityPullmanWA99164‐4236USA
| | - Nuria Koteyeva
- School of Biological SciencesWashington State UniversityPullmanWA99164‐4236USA
- Laboratory of Anatomy and MorphologyV.L. Komarov Botanical Institute of the Russian Academy of Sciences197376St PetersburgRussia
| | - Asaph B. Cousins
- School of Biological SciencesWashington State UniversityPullmanWA99164‐4236USA
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Hilman B, Muhr J, Helm J, Kuhlmann I, Schulze ED, Trumbore S. The size and the age of the metabolically active carbon in tree roots. Plant Cell Environ 2021; 44:2522-2535. [PMID: 34096615 DOI: 10.1111/pce.14124] [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: 03/16/2021] [Revised: 05/31/2021] [Accepted: 06/01/2021] [Indexed: 06/12/2023]
Abstract
Little is known about the sources and age of C respired by tree roots. Previous research in stems identified two functional pools of non-structural carbohydrates (NSC): an "active" pool supplied directly from canopy photo-assimilates supporting metabolism and a "stored" pool used when fresh C supplies are limited. We compared the C isotope composition of water-soluble NSC and respired CO2 for aspen roots (Populus tremula hybrids) cut off from fresh C supply after stem-girdling or prolonged incubation of excised roots. We used bomb radiocarbon to estimate the time elapsed since C fixation for respired CO2 , water-soluble NSC and structural α-cellulose. While freshly excised roots (mostly <2.9 mm in diameter) respired CO2 fixed <1 year previously, the age increased to 1.6-2.9 year within a week after root excision. Freshly excised roots from trees girdled ~3 months ago had respiration rates and NSC stocks similar to un-girdled trees but respired older C (~1.2 year). We estimate that over 3 months NSC in girdled roots must be replaced 5-7 times by reserves remobilized from root-external sources. Using a mixing model and observed correlations between Δ14 C of water-soluble C and α-cellulose, we estimate ~30% of C is "active" (~5 mg C g-1 ).
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Affiliation(s)
- Boaz Hilman
- Department of Biogeochemical Processes, Max-Planck Institute for Biogeochemistry, Jena, Germany
| | - Jan Muhr
- Department of Biogeochemical Processes, Max-Planck Institute for Biogeochemistry, Jena, Germany
- Department of Bioclimatology, Georg-August University Göttingen, Göttingen, Germany
| | - Juliane Helm
- Department of Biogeochemical Processes, Max-Planck Institute for Biogeochemistry, Jena, Germany
| | - Iris Kuhlmann
- Department of Biogeochemical Processes, Max-Planck Institute for Biogeochemistry, Jena, Germany
| | - Ernst-Detlef Schulze
- Department of Biogeochemical Processes, Max-Planck Institute for Biogeochemistry, Jena, Germany
| | - Susan Trumbore
- Department of Biogeochemical Processes, Max-Planck Institute for Biogeochemistry, Jena, Germany
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Hogewoning SW, van den Boogaart SAJ, van Tongerlo E, Trouwborst G. CAM-physiology and carbon gain of the orchid Phalaenopsis in response to light intensity, light integral and CO 2. Plant Cell Environ 2021; 44:762-774. [PMID: 33244775 DOI: 10.1111/pce.13960] [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] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 11/10/2020] [Accepted: 11/16/2020] [Indexed: 06/11/2023]
Abstract
The regulation of photosynthesis and carbon gain of crassulacean acid metabolism (CAM) plants has not yet been disclosed to the extent of C3-plants. In this study, the tropical epiphyte Phalaenopsis cv. "Sacramento" was subjected to different lighting regimes. Photosynthesis and biochemical measuring techniques were used to address four specific questions: (1) the response of malate decarboxylation to light intensity, (2) the malate carboxylation pathway in phase IV, (3) the response of diel carbon gain to the light integral and (4) the response of diel carbon gain to CO2 . The four CAM-phases were clearly discernable. The length of phase III and the malate decarboxylation rate responded directly to light intensity. In phase IV, CO2 was initially mainly carboxylated via Rubisco. However, at daylength of 16 h, specifically beyond ±12 h, it was mainly phosphoenolpyruvate carboxylase (PEP-C) carboxylating CO2 . Diel carbon gain appeared to be controlled by the light integral during phase III rather than the total daily light integral. Elevated CO2 further enhanced carbon gain both in phase IV and phase I. This establishes that neither malate storage capacity, nor availability of PEP as substrate for nocturnal CO2 carboxylation were limiting factors for carbon gain enhancement. These results advance our understanding of CAM-plants and are also of practical importance for growers.
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Affiliation(s)
| | | | - Evelien van Tongerlo
- Horticulture and Product Physiology, Department of Plant Sciences, Wageningen University & Research, Wageningen, The Netherlands
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Czyż KB, Książkiewicz M, Koczyk G, Szczepaniak A, Podkowiński J, Naganowska B. A Tale of Two Families: Whole Genome and Segmental Duplications Underlie Glutamine Synthetase and Phosphoenolpyruvate Carboxylase Diversity in Narrow-Leafed Lupin ( Lupinus angustifolius L.). Int J Mol Sci 2020; 21:E2580. [PMID: 32276381 DOI: 10.3390/ijms21072580] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 04/04/2020] [Accepted: 04/06/2020] [Indexed: 01/04/2023] Open
Abstract
Narrow-leafed lupin (Lupinus angustifolius L.) has recently been supplied with advanced genomic resources and, as such, has become a well-known model for molecular evolutionary studies within the legume family—a group of plants able to fix nitrogen from the atmosphere. The phylogenetic position of lupins in Papilionoideae and their evolutionary distance to other higher plants facilitates the use of this model species to improve our knowledge on genes involved in nitrogen assimilation and primary metabolism, providing novel contributions to our understanding of the evolutionary history of legumes. In this study, we present a complex characterization of two narrow-leafed lupin gene families—glutamine synthetase (GS) and phosphoenolpyruvate carboxylase (PEPC). We combine a comparative analysis of gene structures and a synteny-based approach with phylogenetic reconstruction and reconciliation of the gene family and species history in order to examine events underlying the extant diversity of both families. Employing the available evidence, we show the impact of duplications on the initial complement of the analyzed gene families within the genistoid clade and posit that the function of duplicates has been largely retained. In terms of a broader perspective, our results concerning GS and PEPC gene families corroborate earlier findings pointing to key whole genome duplication/triplication event(s) affecting the genistoid lineage.
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Connell MB, Lee MJY, Li J, Plaxton WC, Jia Z. Structural and biochemical characterization of citrate binding to AtPPC3, a plant-type phosphoenolpyruvate carboxylase from Arabidopsis thaliana. J Struct Biol 2018; 204:507-512. [PMID: 30419358 DOI: 10.1016/j.jsb.2018.11.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 11/02/2018] [Accepted: 11/09/2018] [Indexed: 11/30/2022]
Abstract
Phosphoenolpyruvate carboxylase (PEPC) is a tightly regulated cytosolic enzyme situated at a crucial branch point of central plant metabolism. The structure of AtPPC3, a C3 PEPC isozyme of the model plant Arabidopsis thaliana, in complex with the inhibitors aspartate and citrate was solved at 2.2-Å resolution. This represents the first PEPC structure with citrate bound. Aspartate and citrate binding sites are in close proximity (5.1-5.3 Å) and interactions between citrate and specific residues were identified. Citrate functions as a mixed (allosteric) inhibitor as it reduced AtPPC3's Vmax while increasing Km(PEP) values. The PEP saturation data gave an excellent fit to the mixed inhibition model, yielding Ki and Ki' (citrate) values of 9.3 and 42.5 mM, respectively. Citrate and aspartate inhibition of AtPPC3 was non-additive, likely due to their closely positioned binding sites, their similar negative charge, and type of binding residues. Fewer interactions and lower affinity for citrate support its observed weaker inhibition of AtPPC3 relative to aspartate. Citrate does not appear to induce further conformational change beyond aspartate owing to the similar structural mechanism of inhibition. AtPPC3 largely exhibits root-specific expression in Arabidopsis, where it is markedly upregulated during stresses such as excessive salinity or nutritional Pi deprivation that necessitate large increases in anaplerotic PEP carboxylation. The cytosolic citrate concentration of potato tubers suggests that AtPPC3's inhibition by citrate may be physiologically relevant. Our results provide novel insights into the structural basis of allosteric PEPC control and the kinetic effects brought about upon inhibitor binding.
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Affiliation(s)
- Matthew B Connell
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON K7L 3N6, Canada
| | - Michael J Y Lee
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON K7L 3N6, Canada
| | - Jerry Li
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON K7L 3N6, Canada
| | - William C Plaxton
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON K7L 3N6, Canada; Department of Biology, Queen's University, Kingston, ON K7L 3N6, Canada.
| | - Zongchao Jia
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON K7L 3N6, Canada.
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Kolbe AR, Cousins AB. Mesophyll conductance in Zea mays responds transiently to CO 2 availability: implications for transpiration efficiency in C 4 crops. New Phytol 2018; 217:1463-1474. [PMID: 29220090 DOI: 10.1111/nph.14942] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [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: 08/30/2017] [Accepted: 11/07/2017] [Indexed: 06/07/2023]
Abstract
Mesophyll conductance (gm ) describes the movement of CO2 from the intercellular air spaces below the stomata to the site of initial carboxylation in the mesophyll. In contrast with C3 -gm , little is currently known about the intraspecific variation in C4 -gm or its responsiveness to environmental stimuli. To address these questions, gm was measured on five maize (Zea mays) lines in response to CO2 , employing three different estimates of gm . Each of the methods indicated a significant response of gm to CO2 . Estimates of gm were similar between methods at ambient and higher CO2 , but diverged significantly at low partial pressures of CO2 . These differences are probably driven by incomplete chemical and isotopic equilibrium between CO2 and bicarbonate under these conditions. Carbonic anhydrase and phosphoenolpyruvate carboxylase in vitro activity varied significantly despite similar values of gm and leaf anatomical traits. These results provide strong support for a CO2 response of gm in Z. mays, and indicate that gm in maize is probably driven by anatomical constraints rather than by biochemical limitations. The CO2 response of gm indicates a potential role for facilitated diffusion in C4 -gm . These results also suggest that water-use efficiency could be enhanced in C4 species by targeting gm .
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Affiliation(s)
- Allison R Kolbe
- School of Biological Sciences, Washington State University, Pullman, WA, 99164, USA
| | - Asaph B Cousins
- School of Biological Sciences, Washington State University, Pullman, WA, 99164, USA
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Christin PA, Arakaki M, Osborne CP, Bräutigam A, Sage RF, Hibberd JM, Kelly S, Covshoff S, Wong GKS, Hancock L, Edwards EJ. Shared origins of a key enzyme during the evolution of C4 and CAM metabolism. J Exp Bot 2014; 65:3609-21. [PMID: 24638902 PMCID: PMC4085957 DOI: 10.1093/jxb/eru087] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [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: 05/13/2023]
Abstract
CAM and C4 photosynthesis are two key plant adaptations that have evolved independently multiple times, and are especially prevalent in particular groups of plants, including the Caryophyllales. We investigate the origin of photosynthetic PEPC, a key enzyme of both the CAM and C4 pathways. We combine phylogenetic analyses of genes encoding PEPC with analyses of RNA sequence data of Portulaca, the only plants known to perform both CAM and C4 photosynthesis. Three distinct gene lineages encoding PEPC exist in eudicots (namely ppc-1E1, ppc-1E2 and ppc-2), one of which (ppc-1E1) was recurrently recruited for use in both CAM and C4 photosynthesis within the Caryophyllales. This gene is present in multiple copies in the cacti and relatives, including Portulaca. The PEPC involved in the CAM and C4 cycles of Portulaca are encoded by closely related yet distinct genes. The CAM-specific gene is similar to genes from related CAM taxa, suggesting that CAM has evolved before C4 in these species. The similar origin of PEPC and other genes involved in the CAM and C4 cycles highlights the shared early steps of evolutionary trajectories towards CAM and C4, which probably diverged irreversibly only during the optimization of CAM and C4 phenotypes.
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Affiliation(s)
- Pascal-Antoine Christin
- Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield S10 2TN, UK Department of Ecology and Evolutionary Biology, Brown University, 80 Waterman St., Providence, RI 02912, USA
| | - Monica Arakaki
- Department of Ecology and Evolutionary Biology, Brown University, 80 Waterman St., Providence, RI 02912, USA Departamento de Botánica, Facultad de Ciencias Biológicas and Museo de Historia Natural - UNMSM, Av. Arenales 1256, Lima 11, Peru
| | - Colin P Osborne
- Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield S10 2TN, UK
| | - Andrea Bräutigam
- Institute of Plant Biochemistry, Heinrich-Heine University, 40225 Duesseldorf, Germany
| | - Rowan F Sage
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario M5S 3B2, Canada
| | - Julian M Hibberd
- Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, UK
| | - Steven Kelly
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, UK
| | - Sarah Covshoff
- Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, UK
| | - Gane Ka-Shu Wong
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada Department of Medicine, University of Alberta, Edmonton, Alberta T6G 2E1, Canada BGI-Shenzhen, Beishan Industrial Zone, Yantian District, Shenzhen 518083, China
| | - Lillian Hancock
- Department of Ecology and Evolutionary Biology, Brown University, 80 Waterman St., Providence, RI 02912, USA
| | - Erika J Edwards
- Department of Ecology and Evolutionary Biology, Brown University, 80 Waterman St., Providence, RI 02912, USA
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