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Fan Y, Tcherkez G, Scafaro AP, Taylor NL, Furbank RT, von Caemmerer S, Atkin OK. Variation in leaf dark respiration among C3 and C4 grasses is associated with use of different substrates. Plant Physiol 2024:kiae064. [PMID: 38324704 DOI: 10.1093/plphys/kiae064] [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: 12/04/2023] [Revised: 12/04/2023] [Accepted: 01/11/2024] [Indexed: 02/09/2024]
Abstract
Measurements of respiratory properties have often been made at a single time point either during daytime using dark-adapted leaves or during night-time. The influence of the day-night cycle on respiratory metabolism has received less attention but is crucial to understand photosynthesis and photorespiration. Here, we examined how CO2- and O2-based rates of leaf dark respiration (Rdark) differed between midday (after 30-minute dark adaptation) and midnight in eight C3 and C4 grasses. We used these data to calculate the respiratory quotient (RQ; ratio of CO2 release to O2 uptake), and assessed relationships between Rdark and leaf metabolome. Rdark was higher at midday than midnight, especially in C4 species. The day-night difference in Rdark was more evident when expressed on a CO2 than O2 basis, with the RQ being higher at midday than midnight in all species, except in rice (Oryza sativa). Metabolomic analyses showed little correlation of Rdark or RQ with leaf carbohydrates (sucrose, glucose, fructose or starch) but strong multivariate relationships with other metabolites. The results suggest that rates of Rdark and differences in RQ were determined by several concurrent CO2-producing and O2-consuming metabolic pathways, not only the tricarboxylic acid cycle (organic acids utilisation), but also the pentose phosphate pathway, galactose metabolism, and secondary metabolism. As such, Rdark was time-, type- (C3/C4) and species-dependent, due to the use of different substrates.
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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, Australia
- Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, ACT, Australia
| | - Guillaume Tcherkez
- Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, ACT, Australia
- Institut de Recherche en Horticulture et Semences, INRAe, Université d'Angers, Beaucouzé, France
| | - Andrew P Scafaro
- ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Canberra, ACT, Australia
- Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, ACT, Australia
| | - Nicolas L Taylor
- School of Molecular Sciences and Institute of Agriculture, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, WA, Australia
| | - Robert T Furbank
- Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, ACT, Australia
- ARC Centre of Excellence in for Translational Photosynthesis, Research School of Biology, The Australian National University, Canberra, ACT, Australia
| | - Susanne von Caemmerer
- Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, ACT, Australia
- ARC Centre of Excellence in for Translational Photosynthesis, Research School of Biology, The Australian National University, Canberra, ACT, Australia
| | - Owen K Atkin
- ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Canberra, ACT, Australia
- Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, ACT, Australia
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2
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Coast O, Scafaro AP, Bramley H, Taylor NL, Atkin OK. Photosynthesis in newly developed leaves of heat-tolerant wheat acclimates to long-term nocturnal warming. J Exp Bot 2024; 75:962-978. [PMID: 37935881 PMCID: PMC10837020 DOI: 10.1093/jxb/erad437] [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: 04/03/2023] [Accepted: 11/01/2023] [Indexed: 11/09/2023]
Abstract
We examined photosynthetic traits of pre-existing and newly developed flag leaves of four wheat genotypes grown in controlled-environment experiments. In newly developed leaves, acclimation of the maximum rate of net CO2 assimilation (An) to warm nights (i.e. increased An) was associated with increased capacity of Rubisco carboxylation and photosynthetic electron transport, with Rubisco activation state probably contributing to increased Rubisco activity. Metabolite profiling linked acclimation of An to greater accumulation of monosaccharides and saturated fatty acids in leaves; these changes suggest roles for osmotic adjustment of leaf turgor pressure and maintenance of cell membrane integrity. By contrast, where An decreased under warm nights, the decline was related to lower stomatal conductance and rates of photosynthetic electron transport. Decreases in An occurred despite higher basal PSII thermal stability in all genotypes exposed to warm nights: Tcrit of 45-46.5 °C in non-acclimated versus 43.8-45 °C in acclimated leaves. Pre-existing leaves showed no change in An-temperature response curves, except for an elite heat-tolerant genotype. These findings illustrate the impact of night-time warming on the ability of wheat plants to photosynthesize during the day, thereby contributing to explain the impact of global warming on crop productivity.
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Affiliation(s)
- Onoriode Coast
- ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Canberra, ACT 2601, Australia
- Natural Resources Institute, University of Greenwich, Central Avenue, Chatham Maritime, Kent ME4 4TB, UK
- School of Environmental and Rural Sciences, Faculty of Science, Agriculture, Business, and Law, University of New England, Armidale, NSW 2351, Australia
| | - Andrew P Scafaro
- ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Canberra, ACT 2601, Australia
- Division of Plant Science, Research School of Biology, The Australian National University, Canberra, ACT 2601, Australia
| | - Helen Bramley
- School of Life and Environmental Sciences, Plant Breeding Institute, Sydney Institute of Agriculture, The University of Sydney, Narrabri, NSW 2390, Australia
| | - Nicolas L Taylor
- ARC Centre of Excellence in Plant Energy Biology, School of Molecular Sciences and Institute of Agriculture, The University of Western Australia, Crawley, WA 6009, Australia
| | - 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 Science, Research School of Biology, The Australian National University, Canberra, ACT 2601, Australia
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3
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Zhu L, Scafaro AP, Vierling E, Ball MC, Posch BC, Stock F, Atkin OK. Heat tolerance of a tropical-subtropical rainforest tree species Polyscias elegans: time-dependent dynamic responses of physiological thermostability and biochemistry. New Phytol 2024; 241:715-731. [PMID: 37932881 DOI: 10.1111/nph.19356] [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: 10/26/2022] [Accepted: 10/01/2023] [Indexed: 11/08/2023]
Abstract
Heat stress interrupts physiological thermostability and triggers biochemical responses that are essential for plant survival. However, there is limited knowledge on the speed plants adjust to heat in hours and days, and which adjustments are crucial. Tropical-subtropical rainforest tree species (Polyscias elegans) were heated at 40°C for 5 d, before returning to 25°C for 13 d of recovery. Leaf heat tolerance was quantified using the temperature at which minimal chl a fluorescence sharply rose (Tcrit ). Tcrit , metabolites, heat shock protein (HSP) abundance and membrane lipid fatty acid (FA) composition were quantified. Tcrit increased by 4°C (48-52°C) within 2 h of 40°C exposure, along with rapid accumulation of metabolites and HSPs. By contrast, it took > 2 d for FA composition to change. At least 2 d were required for Tcrit , HSP90, HSP70 and FAs to return to prestress levels. The results highlight the multi-faceted response of P. elegans to heat stress, and how this response varies over the scale of hours to days, culminating in an increased level of photosynthetic heat tolerance. These responses are important for survival of plants when confronted with heat waves amidst ongoing global climate change.
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Affiliation(s)
- Lingling Zhu
- Co-Innovation Center for Sustainable Forestry in Southern China, College of Forestry, Nanjing Forestry University, 159 Longpan Road, Nanjing, 210037, China
- ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, Building 134, The Australian National University, Canberra, ACT, 2601, Australia
- Division of Plant Sciences, Research School of Biology, Building 46, The Australian National University, Canberra, ACT, 2601, Australia
| | - Andrew P Scafaro
- ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, Building 134, The Australian National University, Canberra, ACT, 2601, Australia
- Division of Plant Sciences, Research School of Biology, Building 46, The Australian National University, Canberra, ACT, 2601, Australia
| | - Elizabeth Vierling
- Department of Biochemistry and Molecular Biology, University of Massachusetts Amherst, Amherst, MA, 01003, USA
| | - Marilyn C Ball
- Division of Plant Sciences, Research School of Biology, Building 46, The Australian National University, Canberra, ACT, 2601, Australia
| | - Bradley C Posch
- ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, Building 134, The Australian National University, Canberra, ACT, 2601, Australia
- Division of Plant Sciences, Research School of Biology, Building 46, The Australian National University, Canberra, ACT, 2601, Australia
- Department of Research, Conservation, and Collections, Desert Botanical Garden, Phoenix, AZ, 85008, USA
| | - Frederike Stock
- Division of Plant Sciences, Research School of Biology, Building 46, The Australian National University, Canberra, ACT, 2601, Australia
- Australian Plant Phenomics Facility, Research School of Biology, Building 134, The Australian National University, Canberra, ACT, 2601, Australia
| | - Owen K Atkin
- ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, Building 134, The Australian National University, Canberra, ACT, 2601, Australia
- Division of Plant Sciences, Research School of Biology, Building 46, The Australian National University, Canberra, ACT, 2601, Australia
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4
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Scafaro AP, Posch BC, Evans JR, Farquhar GD, Atkin OK. Rubisco deactivation and chloroplast electron transport rates co-limit photosynthesis above optimal leaf temperature in terrestrial plants. Nat Commun 2023; 14:2820. [PMID: 37198175 DOI: 10.1038/s41467-023-38496-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 05/03/2023] [Indexed: 05/19/2023] Open
Abstract
Net photosynthetic CO2 assimilation rate (An) decreases at leaf temperatures above a relatively mild optimum (Topt) in most higher plants. This decline is often attributed to reduced CO2 conductance, increased CO2 loss from photorespiration and respiration, reduced chloroplast electron transport rate (J), or deactivation of Ribulose-1,5-bisphosphate Carboxylase Oxygenase (Rubisco). However, it is unclear which of these factors can best predict species independent declines in An at high temperature. We show that independent of species, and on a global scale, the observed decline in An with rising temperatures can be effectively accounted for by Rubisco deactivation and declines in J. Our finding that An declines with Rubisco deactivation and J supports a coordinated down-regulation of Rubisco and chloroplast electron transport rates to heat stress. We provide a model that, in the absence of CO2 supply limitations, can predict the response of photosynthesis to short-term increases in leaf temperature.
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Affiliation(s)
- Andrew P Scafaro
- Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia.
- Centre for Entrepreneurial Agri-Technology, Gould Building, Australian National University, Canberra, 2601, Australia.
| | - Bradley C Posch
- Department of Research, Collections and Conservation, Desert Botanical Garden, Phoenix, AZ, USA
| | - John R Evans
- Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
| | - Graham D Farquhar
- Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
| | - Owen K Atkin
- Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
- Centre for Entrepreneurial Agri-Technology, Gould Building, Australian National University, Canberra, 2601, Australia
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5
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O’Leary BM, Scafaro AP, York LM. High-throughput, dynamic, multi-dimensional: an expanding repertoire of plant respiration measurements. Plant Physiol 2023; 191:2070-2083. [PMID: 36638140 PMCID: PMC10069890 DOI: 10.1093/plphys/kiac580] [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: 09/20/2022] [Accepted: 11/30/2022] [Indexed: 06/17/2023]
Abstract
A recent burst of technological innovation and adaptation has greatly improved our ability to capture respiration rate data from plant sources. At the tissue level, several independent respiration measurement options are now available, each with distinct advantages and suitability, including high-throughput sampling capacity. These advancements facilitate the inclusion of respiration rate data into large-scale biological studies such as genetic screens, ecological surveys, crop breeding trials, and multi-omics molecular studies. As a result, our understanding of the correlations of respiration with other biological and biochemical measurements is rapidly increasing. Difficult questions persist concerning the interpretation and utilization of respiration data; concepts such as allocation of respiration to growth versus maintenance, the unnecessary or inefficient use of carbon and energy by respiration, and predictions of future respiration rates in response to environmental change are all insufficiently grounded in empirical data. However, we emphasize that new experimental designs involving novel combinations of respiration rate data with other measurements will flesh-out our current theories of respiration. Furthermore, dynamic recordings of respiration rate, which have long been used at the scale of mitochondria, are increasingly being used at larger scales of size and time to reflect processes of cellular signal transduction and physiological response to the environment. We also highlight how respiratory methods are being better adapted to different plant tissues including roots and seeds, which have been somewhat neglected historically.
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Affiliation(s)
- Brendan M O’Leary
- Saskatoon Research and Development Centre, Agriculture and Agri-food Canada, Saskatoon S7N 0X2, Canada
| | - Andrew P Scafaro
- Research School of Biology, Australian National University, Canberra, ACT 2601, Australia
| | - Larry M York
- Center for Bioenergy Innovation and Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
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Phillips AL, Scafaro AP, Atwell BJ. Photosynthetic traits of Australian wild rice (Oryza australiensis) confer tolerance to extreme daytime temperatures. Plant Mol Biol 2022; 110:347-363. [PMID: 34997897 PMCID: PMC9646608 DOI: 10.1007/s11103-021-01210-3] [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: 07/05/2021] [Accepted: 10/27/2021] [Indexed: 05/08/2023]
Abstract
A wild relative of rice from the Australian savannah was compared with cultivated rice, revealing thermotolerance in growth and photosynthetic processes and a more robust carbon economy in extreme heat. Above ~ 32 °C, impaired photosynthesis compromises the productivity of rice. We compared leaf tissues from heat-tolerant wild rice (Oryza australiensis) with temperate-adapted O. sativa after sustained exposure to heat, as well as diurnal heat shock. Leaf elongation and shoot biomass in O. australiensis were unimpaired at 45 °C, and soluble sugar concentrations trebled during 10 h of a 45 °C shock treatment. By contrast, 45 °C slowed growth strongly in O. sativa. Chloroplastic CO2 concentrations eliminated CO2 supply to chloroplasts as the basis of differential heat tolerance. This directed our attention to carboxylation and the abundance of the heat-sensitive chaperone Rubisco activase (Rca) in each species. Surprisingly, O. australiensis leaves at 45 °C had 50% less Rca per unit Rubisco, even though CO2 assimilation was faster than at 30 °C. By contrast, Rca per unit Rubisco doubled in O. sativa at 45 °C while CO2 assimilation was slower, reflecting its inferior Rca thermostability. Plants grown at 45 °C were simultaneously exposed to 700 ppm CO2 to enhance the CO2 supply to Rubisco. Growth at 45 °C responded to CO2 enrichment in O. australiensis but not O. sativa, reflecting more robust carboxylation capacity and thermal tolerance in the wild rice relative.
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Affiliation(s)
- Aaron L Phillips
- Waite Research Institute and School of Agriculture, Food, and Wine, University of Adelaide, Adelaide, SA, Australia
- Department of Biological Sciences, Macquarie University, Sydney, NSW, Australia
- ARC Centre of Excellence in Plant Energy Biology, School of Agriculture, Food, and Wine, The University of Adelaide, Adelaide, SA, Australia
| | - Andrew P Scafaro
- ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Canberra, ACT, Australia
| | - Brian J Atwell
- Department of Biological Sciences, Macquarie University, Sydney, NSW, Australia.
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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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Posch BC, Zhai D, Coast O, Scafaro AP, Bramley H, Reich P, Ruan YL, Trethowan R, Way DA, Atkin O. Wheat respiratory O2 consumption falls with night warming alongside greater respiratory CO2 loss and reduced biomass. J Exp Bot 2022; 73:915-926. [PMID: 34652413 DOI: 10.1093/jxb/erab454] [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: 06/29/2021] [Accepted: 10/13/2021] [Indexed: 06/13/2023]
Abstract
Warming nights are correlated with declining wheat growth and yield. As a key determinant of plant biomass, respiration consumes O2 as it produces ATP and releases CO2 and is typically reduced under warming to maintain metabolic efficiency. We compared the response of respiratory O2 and CO2 flux to multiple night and day warming treatments in wheat leaves and roots, using one commercial (Mace) and one breeding cultivar grown in controlled environments. We also examined the effect of night warming and a day heatwave on the capacity of the ATP-uncoupled alternative oxidase (AOX) pathway. Under warm nights, plant biomass fell, respiratory CO2 release measured at a common temperature was unchanged (indicating higher rates of CO2 release at prevailing growth temperature), respiratory O2 consumption at a common temperature declined, and AOX pathway capacity increased. The uncoupling of CO2 and O2 exchange and enhanced AOX pathway capacity suggest a reduction in plant energy demand under warm nights (lower O2 consumption), alongside higher rates of CO2 release under prevailing growth temperature (due to a lack of down-regulation of respiratory CO2 release). Less efficient ATP synthesis, teamed with sustained CO2 flux, could thus be driving observed biomass declines under warm nights.
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Affiliation(s)
- Bradley C Posch
- ARC Centre of Excellence in Plant Energy Biology, Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, ACT 2601, Australia
| | - Deping Zhai
- ARC Centre of Excellence in Plant Energy Biology, Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, ACT 2601, Australia
- School of Ecological and Environmental Sciences, East China Normal University, 500 Dongchuan Road, Shanghai 200241, China
| | - Onoriode Coast
- ARC Centre of Excellence in Plant Energy Biology, Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, ACT 2601, Australia
- Natural Resources Institute, University of Greenwich, Central Avenue, Chatham Maritime, Kent ME4 4TB, UK
- School of Environmental and Rural Sciences, Faculty of Science Agriculture Business and Law, University of New England, Armidale, NSW 2351, Australia
| | - Andrew P Scafaro
- ARC Centre of Excellence in Plant Energy Biology, Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, ACT 2601, Australia
| | - Helen Bramley
- Plant Breeding Institute, Sydney Institute of Agriculture & School of Life and Environmental Sciences, The University of Sydney, Narrabri, NSW 2390, Australia
| | - PeterB Reich
- Department of Forest Resources, University of Minnesota, St Paul, MN 55108, USA
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, New South Wales 2753, Australia
- Institute for Global Change Biology and School for Environment and Sustainability, University of Michigan, Ann Arbor, MI 48109, USA
| | - Yong-Ling Ruan
- Australia-China Research Centre for Crop Improvement and School of Environmental and Life Sciences, The University of Newcastle, Callaghan, NSW 2308, Australia
| | - Richard Trethowan
- School of Environmental and Rural Sciences, Faculty of Science Agriculture Business and Law, University of New England, Armidale, NSW 2351, Australia
- School of Life and Environmental Sciences, Plant Breeding Institute, Sydney Institute of Agriculture, The University of Sydney, Cobbitty, NSW 2570, Australia
| | - Danielle A Way
- Department of Biology, The University of Western Ontario, 1151 Richmond St., N6A 3K7, London, Canada
- Nicholas School of the Environment, Duke University, 9 Circuit Dr., 27710, Durham, NC, USA
- Environmental and Climate Sciences Department, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - OwenK Atkin
- ARC Centre of Excellence in Plant Energy Biology, Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, ACT 2601, Australia
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9
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Scafaro AP, Fan Y, Posch BC, Garcia A, Coast O, Atkin OK. Responses of leaf respiration to heatwaves. Plant Cell Environ 2021; 44:2090-2101. [PMID: 33534189 DOI: 10.1111/pce.14018] [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: 12/21/2020] [Revised: 01/21/2021] [Accepted: 01/23/2021] [Indexed: 06/12/2023]
Abstract
Mitochondrial respiration (R) is central to plant physiology and responds dynamically to daily short-term temperature changes. In the longer-term, changes in energy demand and membrane fluidity can decrease leaf R at a common temperature and increase the temperature at which leaf R peaks (Tmax ). However, leaf R functionality is more susceptible to short-term heatwaves. Catalysis increases with rising leaf temperature, driving faster metabolism and leaf R demand, despite declines in photosynthesis restricting assimilate supply and growth. Proteins denature as temperatures increase further, adding to maintenance costs. Excessive heat also inactivates respiratory enzymes, with a concomitant limitation on the capacity of the R system. These competing push-and-pull factors are responsible for the diminishing acceleration in leaf R rate as temperature rises. Under extreme heat, membranes become overly fluid, and enzymes such as the cytochrome c oxidase are impaired. Such changes can lead to over-reduction of the energy system culminating in reactive oxygen species production. This ultimately leads to the total breakdown of leaf R, setting the limit of leaf survival. Understanding the heat stress responses of leaf R is imperative, given the continued rise in frequency and intensity of heatwaves and the importance of R for plant fitness and survival.
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Affiliation(s)
- Andrew P Scafaro
- ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Canberra, Australian Capital Territory, Australia
| | - Yuzhen Fan
- ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Canberra, Australian Capital Territory, Australia
| | - Bradley C Posch
- ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Canberra, Australian Capital Territory, Australia
| | - Andres Garcia
- ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Canberra, Australian Capital Territory, Australia
| | - Onoriode Coast
- ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Canberra, Australian Capital Territory, Australia
- Natural Resources Institute, Agriculture, Health and Environment Department, University of Greenwich, Kent, UK
| | - Owen K Atkin
- ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Canberra, Australian Capital Territory, Australia
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10
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Rashid FAA, Scafaro AP, Asao S, Fenske R, Dewar RC, Masle J, Taylor NL, Atkin OK. Diel- and temperature-driven variation of leaf dark respiration rates and metabolite levels in rice. New Phytol 2020; 228:56-69. [PMID: 32415853 DOI: 10.1111/nph.16661] [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: 02/25/2020] [Accepted: 05/01/2020] [Indexed: 06/11/2023]
Abstract
Leaf respiration in the dark (Rdark ) is often measured at a single time during the day, with hot-acclimation lowering Rdark at a common measuring temperature. However, it is unclear whether the diel cycle influences the extent of thermal acclimation of Rdark , or how temperature and time of day interact to influence respiratory metabolites. To examine these issues, we grew rice under 25°C : 20°C, 30°C : 25°C and 40°C : 35°C day : night cycles, measuring Rdark and changes in metabolites at five time points spanning a single 24-h period. Rdark differed among the treatments and with time of day. However, there was no significant interaction between time and growth temperature, indicating that the diel cycle does not alter thermal acclimation of Rdark . Amino acids were highly responsive to the diel cycle and growth temperature, and many were negatively correlated with carbohydrates and with organic acids of the tricarboxylic acid (TCA) cycle. Organic TCA intermediates were significantly altered by the diel cycle irrespective of growth temperature, which we attributed to light-dependent regulatory control of TCA enzyme activities. Collectively, our study shows that environmental disruption of the balance between respiratory substrate supply and demand is corrected for by shifts in TCA-dependent metabolites.
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Affiliation(s)
- Fatimah Azzahra Ahmad Rashid
- Australian Research Council Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
- Department of Biology, Faculty of Science and Mathematics, Sultan Idris Education University, 35900 Tanjung Malim, Perak, Malaysia
| | - Andrew P Scafaro
- Australian Research Council Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
| | - Shinichi Asao
- Australian Research Council Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
| | - Ricarda Fenske
- Australian Research Council Centre of Excellence in Plant Energy Biology, School of Molecular Sciences and Institute of Agriculture, Faculty of Science, The University of Western Australia, Crawley, WA, 6009, Australia
| | - Roderick C Dewar
- Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
- Institute for Atmospheric and Earth System Research/Physics, University of Helsinki, Helsinki, Finland
| | - Josette Masle
- Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
| | - Nicolas L Taylor
- Australian Research Council Centre of Excellence in Plant Energy Biology, School of Molecular Sciences and Institute of Agriculture, Faculty of Science, The University of Western Australia, Crawley, WA, 6009, Australia
| | - Owen K Atkin
- Australian Research Council Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
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Rashid FAA, Crisp PA, Zhang Y, Berkowitz O, Pogson BJ, Day DA, Masle J, Dewar RC, Whelan J, Atkin OK, Scafaro AP. Molecular and physiological responses during thermal acclimation of leaf photosynthesis and respiration in rice. Plant Cell Environ 2020; 43:594-610. [PMID: 31860752 DOI: 10.1111/pce.13706] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [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: 11/01/2019] [Revised: 12/15/2019] [Accepted: 12/16/2019] [Indexed: 05/24/2023]
Abstract
To further our understanding of how sustained changes in temperature affect the carbon economy of rice (Oryza sativa), hydroponically grown plants of the IR64 cultivar were developed at 30°C/25°C (day/night) before being shifted to 25/20°C or 40/35°C. Leaf messenger RNA and protein abundance, sugar and starch concentrations, and gas-exchange and elongation rates were measured on preexisting leaves (PE) already developed at 30/25°C or leaves newly developed (ND) subsequent to temperature transfer. Following a shift in growth temperature, there was a transient adjustment in metabolic gene transcript abundance of PE leaves before homoeostasis was reached within 24 hr, aligning with Rdark (leaf dark respiratory CO2 release) and An (net CO2 assimilation) changes. With longer exposure, the central respiratory protein cytochrome c oxidase (COX) declined in abundance at 40/35°C. In contrast to Rdark , An was maintained across the three growth temperatures in ND leaves. Soluble sugars did not differ significantly with growth temperature, and growth was fastest with extended exposure at 40/35°C. The results highlight that acclimation of photosynthesis and respiration is asynchronous in rice, with heat-acclimated plants exhibiting a striking ability to maintain net carbon gain and growth when exposed to heat-wave temperatures, even while reducing investment in energy-conserving respiratory pathways.
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Affiliation(s)
- Fatimah Azzahra Ahmad Rashid
- Australian Research Council Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Canberra, Australian Capital Territory, Australia
- Department of Biology, Faculty of Science and Mathematics, Sultan Idris Education University, Tanjung Malim, Malaysia
| | - Peter A Crisp
- Department of Plant and Microbial Biology, University of Minnesota, Saint Paul, Minnesota
| | - You Zhang
- CSIRO Plant Industry, Canberra, Australian Capital Territory, Australia
| | - Oliver Berkowitz
- Australian Research Council Centre of Excellence in Plant Energy Biology, School of Life Science, AgriBio Building, La Trobe University, Melbourne, Victoria, Australia
| | - Barry J Pogson
- Australian Research Council Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Canberra, Australian Capital Territory, Australia
| | - David A Day
- College of Science and Engineering, Flinders University, Adelaide, South Australia, Australia
- Department of Animal, Plant and Soil Sciences, AgriBio Building, La Trobe University, Melbourne, Victoria, Australia
| | - Josette Masle
- Research School of Biology, The Australian National University, Canberra, Australia
| | - Roderick C Dewar
- Research School of Biology, The Australian National University, Canberra, Australia
- Institute for Atmospheric and Earth System Research/Physics, University of Helsinki, Helsinki, Finland
| | - James Whelan
- Australian Research Council Centre of Excellence in Plant Energy Biology, School of Life Science, AgriBio Building, La Trobe University, Melbourne, Victoria, Australia
| | - Owen K Atkin
- Australian Research Council Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Canberra, Australian Capital Territory, Australia
| | - Andrew P Scafaro
- Australian Research Council Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Canberra, Australian Capital Territory, Australia
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Scafaro AP, De Vleesschauwer D, Bautsoens N, Hannah MA, den Boer B, Gallé A, Van Rie J. A single point mutation in the C-terminal extension of wheat Rubisco activase dramatically reduces ADP inhibition via enhanced ATP binding affinity. J Biol Chem 2019; 294:17931-17940. [PMID: 31530638 PMCID: PMC6879333 DOI: 10.1074/jbc.ra119.010684] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Revised: 09/15/2019] [Indexed: 01/23/2023] Open
Abstract
Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activase (Rca) is a AAA+ enzyme that uses ATP to remove inhibitors from the active site of Rubisco, the central carboxylation enzyme of photosynthesis. Rca α and β isoforms exist in most higher plant species, with the α isoform being identical to the β form but having an additional 25-45 amino acids at the Rca C terminus, known as the C-terminal extension (CTE). Rca is inhibited by ADP, and the extent of ADP sensitivity of the Rca complex can be modulated by the CTE of the α isoform, particularly in relation to a disulfide bond structure that is specifically reduced by the redox-regulatory enzyme thioredoxin-f. Here, we introduced single point mutations of Lys-428 in the CTE of Rca-α from wheat (Triticum aestivum) (TaRca2-α). Substitution of Lys-428 with Arg dramatically altered ADP inhibition, independently of thioredoxin-f regulation. We determined that the reduction in ADP inhibition in the K428R variant is not due to a change in ADP affinity, as the apparent constant for ADP binding was not altered by the K428R substitution. Rather, we observed that the K428R substitution strongly increased ATP substrate affinity and ATP-dependent catalytic velocity. These results suggest that the Lys-428 residue is involved in interacting with the γ-phosphate of ATP. Considering that nucleotide-dependent Rca activity regulates Rubisco and thus photosynthesis during fluctuating irradiance, the K428R substitution could potentially provide a mechanism for boosting the performance of wheat grown in the dynamic light environments of the field.
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Affiliation(s)
- Andrew P Scafaro
- BASF Belgium Coordination Center-Innovation Center Gent, Technologiepark 101, Gent 9052, Belgium
| | - David De Vleesschauwer
- BASF Belgium Coordination Center-Innovation Center Gent, Technologiepark 101, Gent 9052, Belgium
| | - Nadine Bautsoens
- BASF Belgium Coordination Center-Innovation Center Gent, Technologiepark 101, Gent 9052, Belgium
| | - Matthew A Hannah
- BASF Belgium Coordination Center-Innovation Center Gent, Technologiepark 101, Gent 9052, Belgium
| | - Bart den Boer
- BASF Belgium Coordination Center-Innovation Center Gent, Technologiepark 101, Gent 9052, Belgium
| | - Alexander Gallé
- BASF Belgium Coordination Center-Innovation Center Gent, Technologiepark 101, Gent 9052, Belgium
| | - Jeroen Van Rie
- BASF Belgium Coordination Center-Innovation Center Gent, Technologiepark 101, Gent 9052, Belgium
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13
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Scafaro AP, Bautsoens N, den Boer B, Van Rie J, Gallé A. A Conserved Sequence from Heat-Adapted Species Improves Rubisco Activase Thermostability in Wheat. Plant Physiol 2019; 181:43-54. [PMID: 31189658 PMCID: PMC6716234 DOI: 10.1104/pp.19.00425] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 05/31/2019] [Indexed: 05/06/2023]
Abstract
The central enzyme of photosynthesis, Rubisco, is regulated by Rubisco activase (Rca). Photosynthesis is impaired during heat stress, and this limitation is often attributed to the heat-labile nature of Rca. We characterized gene expression and protein thermostability for the three Rca isoforms present in wheat (Triticum aestivum), namely TaRca1-β, TaRca2-α, and TaRca2-β. Furthermore, we compared wheat Rca with one of the two Rca isoforms from rice (Oryza sativa; OsRca-β) and Rca from other species adapted to warm environments. The TaRca1 gene was induced, whereas TaRca2 was suppressed by heat stress. The TaRca2 isoforms were sensitive to heat degradation, with thermal midpoints of 35°C ± 0.3°C, the temperature at which Rubisco activation velocity by Rca was halved. By contrast, TaRca1-β was more thermotolerant, with a thermal midpoint of 42°C, matching that of rice OsRca-β. Mutations of the TaRca2-β isoform based on sequence alignment of the thermostable TaRca1-β from wheat, OsRca-β from rice, and a consensus sequence representing Rca from warm-adapted species enabled the identification of 11 amino acid substitutions that improved its thermostability by greater than 7°C without a reduction in catalytic velocity at a standard 25°C. Protein structure modeling and mutational analysis suggested that the thermostability of these mutational variants arises from monomeric and not oligomeric thermal stabilization. These results provide a mechanism for improving the heat stress tolerance of photosynthesis in wheat and potentially other species, which is a desirable outcome considering the likelihood that crops will face more frequent heat stress conditions over the coming decades.
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Affiliation(s)
- Andrew P Scafaro
- BASF Agricultural Solutions, Ghent 9052, Belgium
- Australian Research Council Centre of Excellence in Plant Energy Biology, Research School of Biology, Australian National University, Canberra, Australian Capital Territory 2601, Australia
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14
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Bahar NHA, Hayes L, Scafaro AP, Atkin OK, Evans JR. Mesophyll conductance does not contribute to greater photosynthetic rate per unit nitrogen in temperate compared with tropical evergreen wet-forest tree leaves. New Phytol 2018; 218:492-505. [PMID: 29436710 DOI: 10.1111/nph.15031] [Citation(s) in RCA: 8] [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: 08/28/2017] [Accepted: 12/23/2017] [Indexed: 05/26/2023]
Abstract
Globally, trees originating from high-rainfall tropical regions typically exhibit lower rates of light-saturated net CO2 assimilation (A) compared with those from high-rainfall temperate environments, when measured at a common temperature. One factor that has been suggested to contribute towards lower rates of A is lower mesophyll conductance. Using a combination of leaf gas exchange and carbon isotope discrimination measurements, we estimated mesophyll conductance (gm ) of several Australian tropical and temperate wet-forest trees, grown in a common environment. Maximum Rubisco carboxylation capacity, Vcmax , was obtained from CO2 response curves. gm and the drawdown of CO2 across the mesophyll were both relatively constant. Vcmax estimated on the basis of intercellular CO2 partial pressure, Ci , was equivalent to that estimated using chloroplastic CO2 partial pressure, Cc , using 'apparent' and 'true' Rubisco Michaelis-Menten constants, respectively Having ruled out gm as a possible factor in distorting variations in A between these tropical and temperate trees, attention now needs to be focused on obtaining more detailed information about Rubisco in these species.
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Affiliation(s)
- Nur H A Bahar
- ARC Centre of Excellence in Plant Energy Biology, Division of Plant Sciences, Research School of Biology, Australian National University, Canberra, ACT, 2601, Australia
| | - Lucy Hayes
- ARC Centre of Excellence in Plant Energy Biology, Division of Plant Sciences, Research School of Biology, Australian National University, Canberra, ACT, 2601, Australia
| | - Andrew P Scafaro
- ARC Centre of Excellence in Plant Energy Biology, Division of Plant Sciences, Research School of Biology, Australian National University, Canberra, ACT, 2601, Australia
| | - Owen K Atkin
- ARC Centre of Excellence in Plant Energy Biology, Division of Plant Sciences, Research School of Biology, Australian National University, Canberra, ACT, 2601, Australia
| | - John R Evans
- ARC Centre of Excellence for Translational Photosynthesis, Division of Plant Sciences, Research School of Biology, Australian National University, Canberra, ACT, 2601, Australia
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15
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Scafaro AP, Atwell BJ, Muylaert S, Reusel BV, Ruiz GA, Rie JV, Gallé A. A Thermotolerant Variant of Rubisco Activase From a Wild Relative Improves Growth and Seed Yield in Rice Under Heat Stress. Front Plant Sci 2018; 9:1663. [PMID: 30524456 PMCID: PMC6256286 DOI: 10.3389/fpls.2018.01663] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Accepted: 10/26/2018] [Indexed: 05/03/2023]
Abstract
Genes encoding thermostable variants of the photosynthesis heat-labile protein Rubisco activase (Rca) from a wild relative Oryza australiensis were overexpressed in domesticated rice (Oryza sativa). Proteomics was used to quantify the abundance of O. australiensis Rca (Rca-Oa) in the resulting plants. Plants were grown to maturity in growth rooms and from early tillering until immediately prior to anthesis, they were exposed to daytime maximum temperatures of 28, 40, and 45°C and constant night temperatures of 22°C. Non-destructive measurements of leaf elongation and photosynthesis were used to compare the null segregant with a transfected line in which 19% of its total Rca content was the recombinant O. australiensis Rca (T-Oa-19). Height, fresh mass, panicle number, seed set, and seed number were measured at final harvest. Traits at maturity after heat stress at 45°C correlated strongly with recombinant protein abundance. Seed number was far the most responsive trait to an increase in Rca-Oa abundance, improving by up to 150%. Leaf elongation rates (LER) and tiller number were significantly greater in the transformed plants in the first two weeks of exposure to 45°C but tiller numbers later became equal in the two genotypes. Gas exchange measurements showed that T-Oa-19 had faster light induction of photosynthesis but not significantly higher CO2 assimilation rates, indicating that the carbon gain that resulted in large yield improvement after growth at 45°C was not strongly correlated with an instantaneous measurement of steady-state photosynthesis. When plants were grown at 40°C daytime maximum, there was no improvement in the final biomass, panicle or seed number when compared with 28°C, indicating that the threshold for heat damage and beneficial effects of the thermostable Rca recombinant protein was between 40 and 45°C, which corresponded to leaf temperatures in the range 38-42°C. The results suggest that the thermotolerant form of Rca from O. australiensis was sufficient to enhance carbohydrate accumulation and storage by rice over the life of the plant, dramatically improving yields after exposure to heat throughout the vegetative phase.
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Affiliation(s)
- Andrew P. Scafaro
- Bayer CropScience SA-NV, Innovation Center Ghent, Ghent, Belgium
- *Correspondence: Andrew P. Scafaro,
| | - Brian J. Atwell
- Department of Biological Sciences, Macquarie University, Sydney, NSW, Australia
| | - Steven Muylaert
- Bayer CropScience SA-NV, Innovation Center Ghent, Ghent, Belgium
| | | | | | - Jeroen Van Rie
- Bayer CropScience SA-NV, Innovation Center Ghent, Ghent, Belgium
| | - Alexander Gallé
- Bayer CropScience SA-NV, Innovation Center Ghent, Ghent, Belgium
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16
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Scafaro AP, Xiang S, Long BM, Bahar NHA, Weerasinghe LK, Creek D, Evans JR, Reich PB, Atkin OK. Strong thermal acclimation of photosynthesis in tropical and temperate wet-forest tree species: the importance of altered Rubisco content. Glob Chang Biol 2017; 23:2783-2800. [PMID: 27859952 DOI: 10.1111/gcb.13566] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2016] [Accepted: 10/16/2016] [Indexed: 05/09/2023]
Abstract
Understanding of the extent of acclimation of light-saturated net photosynthesis (An ) to temperature (T), and associated underlying mechanisms, remains limited. This is a key knowledge gap given the importance of thermal acclimation for plant functioning, both under current and future higher temperatures, limiting the accuracy and realism of Earth system model (ESM) predictions. Given this, we analysed and modelled T-dependent changes in photosynthetic capacity in 10 wet-forest tree species: six from temperate forests and four from tropical forests. Temperate and tropical species were each acclimated to three daytime growth temperatures (Tgrowth ): temperate - 15, 20 and 25 °C; tropical - 25, 30 and 35 °C. CO2 response curves of An were used to model maximal rates of RuBP (ribulose-1,5-bisphosphate) carboxylation (Vcmax ) and electron transport (Jmax ) at each treatment's respective Tgrowth and at a common measurement T (25 °C). SDS-PAGE gels were used to determine abundance of the CO2 -fixing enzyme, Rubisco. Leaf chlorophyll, nitrogen (N) and mass per unit leaf area (LMA) were also determined. For all species and Tgrowth , An at current atmospheric CO2 partial pressure was Rubisco-limited. Across all species, LMA decreased with increasing Tgrowth . Similarly, area-based rates of Vcmax at a measurement T of 25 °C (Vcmax25 ) linearly declined with increasing Tgrowth , linked to a concomitant decline in total leaf protein per unit leaf area and Rubisco as a percentage of leaf N. The decline in Rubisco constrained Vcmax and An for leaves developed at higher Tgrowth and resulted in poor predictions of photosynthesis by currently widely used models that do not account for Tgrowth -mediated changes in Rubisco abundance that underpin the thermal acclimation response of photosynthesis in wet-forest tree species. A new model is proposed that accounts for the effect of Tgrowth -mediated declines in Vcmax25 on An , complementing current photosynthetic thermal acclimation models that do not account for T sensitivity of Vcmax25 .
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Affiliation(s)
- Andrew P Scafaro
- ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Building 134, Canberra, ACT, 2601, Australia
| | - Shuang Xiang
- Chengdu Institute of Biology, Chinese Academy of Sciences, No. 9, Section 4, Renmin South Road, Chengdu, Sichuan, 610041, China
- Division of Plant Sciences, Research School of Biology, The Australian National University, Building 46, Canberra, ACT, 2601, Australia
| | - Benedict M Long
- Division of Plant Sciences, Research School of Biology, The Australian National University, Building 46, Canberra, ACT, 2601, Australia
- ARC Centre of Excellence for Translational Photosynthesis, Research School of Biology, The Australian National University, Building 134, Canberra, ACT, 2601, Australia
| | - Nur H A Bahar
- ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Building 134, Canberra, ACT, 2601, Australia
| | | | - Danielle Creek
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, 2751, Australia
| | - John R Evans
- Division of Plant Sciences, Research School of Biology, The Australian National University, Building 46, Canberra, ACT, 2601, Australia
- ARC Centre of Excellence for Translational Photosynthesis, Research School of Biology, The Australian National University, Building 134, Canberra, ACT, 2601, Australia
| | - Peter B Reich
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, 2751, Australia
- Department of Forest Resources, University of Minnesota, 1540 Cleveland Avenue North, St. Paul, MN, 55108, USA
| | - Owen K Atkin
- ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Building 134, Canberra, ACT, 2601, Australia
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17
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Scafaro AP, Negrini ACA, O’Leary B, Rashid FAA, Hayes L, Fan Y, Zhang Y, Chochois V, Badger MR, Millar AH, Atkin OK. The combination of gas-phase fluorophore technology and automation to enable high-throughput analysis of plant respiration. Plant Methods 2017; 13:16. [PMID: 28344635 PMCID: PMC5361846 DOI: 10.1186/s13007-017-0169-3] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Accepted: 03/17/2017] [Indexed: 05/18/2023]
Abstract
BACKGROUND Mitochondrial respiration in the dark (Rdark) is a critical plant physiological process, and hence a reliable, efficient and high-throughput method of measuring variation in rates of Rdark is essential for agronomic and ecological studies. However, currently methods used to measure Rdark in plant tissues are typically low throughput. We assessed a high-throughput automated fluorophore system of detecting multiple O2 consumption rates. The fluorophore technique was compared with O2-electrodes, infrared gas analysers (IRGA), and membrane inlet mass spectrometry, to determine accuracy and speed of detecting respiratory fluxes. RESULTS The high-throughput fluorophore system provided stable measurements of Rdark in detached leaf and root tissues over many hours. High-throughput potential was evident in that the fluorophore system was 10 to 26-fold faster per sample measurement than other conventional methods. The versatility of the technique was evident in its enabling: (1) rapid screening of Rdark in 138 genotypes of wheat; and, (2) quantification of rarely-assessed whole-plant Rdark through dissection and simultaneous measurements of above- and below-ground organs. DISCUSSION Variation in absolute Rdark was observed between techniques, likely due to variation in sample conditions (i.e. liquid vs. gas-phase, open vs. closed systems), indicating that comparisons between studies using different measuring apparatus may not be feasible. However, the high-throughput protocol we present provided similar values of Rdark to the most commonly used IRGA instrument currently employed by plant scientists. Together with the greater than tenfold increase in sample processing speed, we conclude that the high-throughput protocol enables reliable, stable and reproducible measurements of Rdark on multiple samples simultaneously, irrespective of plant or tissue type.
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Affiliation(s)
- Andrew P. Scafaro
- ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, Building 134, The Australian National University, Canberra, ACT 2601 Australia
- Bayer CropScience SA-NV, Technologiepark 38, 9052 Gent (Zwijnaarde), Belgium
| | - A. Clarissa A. Negrini
- ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, Building 134, The Australian National University, Canberra, ACT 2601 Australia
| | - Brendan O’Leary
- ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, Building 134, The Australian National University, Canberra, ACT 2601 Australia
- Australian Research Council Centre of Excellence in Plant Energy Biology, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009 Australia
| | - F. Azzahra Ahmad Rashid
- ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, Building 134, The Australian National University, Canberra, ACT 2601 Australia
| | - Lucy Hayes
- ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, Building 134, The Australian National University, Canberra, ACT 2601 Australia
| | - Yuzhen Fan
- ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, Building 134, The Australian National University, Canberra, ACT 2601 Australia
| | - You Zhang
- ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, Building 134, The Australian National University, Canberra, ACT 2601 Australia
| | - Vincent Chochois
- ARC Centre of Excellence for Translational Photosynthesis, Building 134, The Australian National University, Canberra, ACT 2601 Australia
| | - Murray R. Badger
- ARC Centre of Excellence for Translational Photosynthesis, Building 134, The Australian National University, Canberra, ACT 2601 Australia
| | - A. Harvey Millar
- Australian Research Council Centre of Excellence in Plant Energy Biology, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009 Australia
| | - Owen K. Atkin
- ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, Building 134, The Australian National University, Canberra, ACT 2601 Australia
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18
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Scafaro AP, Negrini ACA, O'Leary B, Rashid FAA, Hayes L, Fan Y, Zhang Y, Chochois V, Badger MR, Millar AH, Atkin OK. The combination of gas-phase fluorophore technology and automation to enable high-throughput analysis of plant respiration. Plant Methods 2017; 13:16. [PMID: 28344635 DOI: 10.1186/s13007-017-0169-163] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Accepted: 03/17/2017] [Indexed: 05/22/2023]
Abstract
BACKGROUND Mitochondrial respiration in the dark (Rdark) is a critical plant physiological process, and hence a reliable, efficient and high-throughput method of measuring variation in rates of Rdark is essential for agronomic and ecological studies. However, currently methods used to measure Rdark in plant tissues are typically low throughput. We assessed a high-throughput automated fluorophore system of detecting multiple O2 consumption rates. The fluorophore technique was compared with O2-electrodes, infrared gas analysers (IRGA), and membrane inlet mass spectrometry, to determine accuracy and speed of detecting respiratory fluxes. RESULTS The high-throughput fluorophore system provided stable measurements of Rdark in detached leaf and root tissues over many hours. High-throughput potential was evident in that the fluorophore system was 10 to 26-fold faster per sample measurement than other conventional methods. The versatility of the technique was evident in its enabling: (1) rapid screening of Rdark in 138 genotypes of wheat; and, (2) quantification of rarely-assessed whole-plant Rdark through dissection and simultaneous measurements of above- and below-ground organs. DISCUSSION Variation in absolute Rdark was observed between techniques, likely due to variation in sample conditions (i.e. liquid vs. gas-phase, open vs. closed systems), indicating that comparisons between studies using different measuring apparatus may not be feasible. However, the high-throughput protocol we present provided similar values of Rdark to the most commonly used IRGA instrument currently employed by plant scientists. Together with the greater than tenfold increase in sample processing speed, we conclude that the high-throughput protocol enables reliable, stable and reproducible measurements of Rdark on multiple samples simultaneously, irrespective of plant or tissue type.
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Affiliation(s)
- Andrew P Scafaro
- ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, Building 134, The Australian National University, Canberra, ACT 2601 Australia
- Bayer CropScience SA-NV, Technologiepark 38, 9052 Gent (Zwijnaarde), Belgium
| | - A Clarissa A Negrini
- ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, Building 134, The Australian National University, Canberra, ACT 2601 Australia
| | - Brendan O'Leary
- ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, Building 134, The Australian National University, Canberra, ACT 2601 Australia
- Australian Research Council Centre of Excellence in Plant Energy Biology, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009 Australia
| | - F Azzahra Ahmad Rashid
- ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, Building 134, The Australian National University, Canberra, ACT 2601 Australia
| | - Lucy Hayes
- ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, Building 134, The Australian National University, Canberra, ACT 2601 Australia
| | - Yuzhen Fan
- ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, Building 134, The Australian National University, Canberra, ACT 2601 Australia
| | - You Zhang
- ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, Building 134, The Australian National University, Canberra, ACT 2601 Australia
| | - Vincent Chochois
- ARC Centre of Excellence for Translational Photosynthesis, Building 134, The Australian National University, Canberra, ACT 2601 Australia
| | - Murray R Badger
- ARC Centre of Excellence for Translational Photosynthesis, Building 134, The Australian National University, Canberra, ACT 2601 Australia
| | - A Harvey Millar
- Australian Research Council Centre of Excellence in Plant Energy Biology, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009 Australia
| | - Owen K Atkin
- ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, Building 134, The Australian National University, Canberra, ACT 2601 Australia
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19
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Scafaro AP, Gallé A, Van Rie J, Carmo-Silva E, Salvucci ME, Atwell BJ. Heat tolerance in a wild Oryza species is attributed to maintenance of Rubisco activation by a thermally stable Rubisco activase ortholog. New Phytol 2016; 211:899-911. [PMID: 27145723 DOI: 10.1111/nph.13963] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [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: 09/10/2015] [Accepted: 03/03/2016] [Indexed: 05/10/2023]
Abstract
The mechanistic basis of tolerance to heat stress was investigated in Oryza sativa and two wild rice species, Oryza meridionalis and Oryza australiensis. The wild relatives are endemic to the hot, arid Australian savannah. Leaf elongation rates and gas exchange were measured during short periods of supra-optimal heat, revealing species differences. The Rubisco activase (RCA) gene from each species was sequenced. Using expressed recombinant RCA and leaf-extracted RCA, the kinetic properties of the two isoforms were studied under high temperatures. Leaf elongation was undiminished at 45°C in O. australiensis. The net photosynthetic rate was almost 50% slower in O. sativa at 45°C than at 28°C, while in O. australiensis it was unaffected. Oryza meridionalis exhibited intermediate heat tolerance. Based on previous reports that RCA is heat-labile, the Rubisco activation state was measured. It correlated positively with leaf elongation rates across all three species and four periods of exposure to 45°C. Sequence analysis revealed numerous polymorphisms in the RCA amino acid sequence from O. australiensis. The O. australiensis RCA enzyme was thermally stable up to 42°C, contrasting with RCA from O. sativa, which was inhibited at 36°C. We attribute heat tolerance in the wild species to thermal stability of RCA, enabling Rubisco to remain active.
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Affiliation(s)
- Andrew P Scafaro
- Department of Biological Sciences, Faculty of Science and Engineering, Macquarie University, Sydney, NSW, 2109, Australia
- ARC Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Canberra, ACT, 0200, Australia
| | - Alexander Gallé
- Bayer CropScience NV, Innovation Center - Trait Research, Technologiepark 38, Zwijnaarde (Gent), 9052, Belgium
| | - Jeroen Van Rie
- Bayer CropScience NV, Innovation Center - Trait Research, Technologiepark 38, Zwijnaarde (Gent), 9052, Belgium
| | | | - Michael E Salvucci
- US Department of Agriculture, Agricultural Research Service, Arid-Land Agricultural Research Center, Maricopa, AZ, 85138, USA
| | - Brian J Atwell
- Department of Biological Sciences, Faculty of Science and Engineering, Macquarie University, Sydney, NSW, 2109, Australia
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Atwell BJ, Wang H, Scafaro AP. Could abiotic stress tolerance in wild relatives of rice be used to improve Oryza sativa? Plant Sci 2014; 215-216:48-58. [PMID: 24388514 DOI: 10.1016/j.plantsci.2013.10.007] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [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: 07/21/2013] [Revised: 09/28/2013] [Accepted: 10/11/2013] [Indexed: 05/02/2023]
Abstract
Oryza sativa and Oryza glaberrima have been selected to acquire and partition resources efficiently as part of the process of domestication. However, genetic diversity in cultivated rice is limited compared to wild Oryza species, in spite of 120,000 genotypes being held in gene banks. By contrast, there is untapped diversity in the more than 20 wild species of Oryza, some having been collected from just a few coastal locations (e.g. Oryza schlechteri), while others are widely distributed (e.g. Oryza nivara and Oryza rufipogon). The extent of DNA sequence diversity and phenotypic variation is still being established in wild Oryza, with genetic barriers suggesting a vast range of morphologies and function even within species, such as has been demonstrated for Oryza meridionalis. With increasing climate variability and attempts to make more marginal land arable, abiotic and biotic stresses will be managed over the coming decades by tapping into the genetic diversity of wild relatives of O. sativa. To help create a more targeted approach to sourcing wild rice germplasm for abiotic stress tolerance, we have created a climate distribution map by plotting the natural occurrence of all Oryza species against corresponding temperature and moisture data. We then discuss interspecific variation in phenotype and its significance for rice, followed by a discussion of ways to integrate germplasm from wild relatives into domesticated rice.
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Affiliation(s)
- Brian J Atwell
- Department of Biological Sciences, Faculty of Science, Macquarie University, New South Wales 2109, Australia.
| | - Han Wang
- Department of Biological Sciences, Faculty of Science, Macquarie University, New South Wales 2109, Australia
| | - Andrew P Scafaro
- Department of Biological Sciences, Faculty of Science, Macquarie University, New South Wales 2109, Australia
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21
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Neilson KA, Scafaro AP, Chick JM, George IS, Van Sluyter SC, Gygi SP, Atwell BJ, Haynes PA. The influence of signals from chilled roots on the proteome of shoot tissues in rice seedlings. Proteomics 2013; 13:1922-33. [DOI: 10.1002/pmic.201200475] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Revised: 12/06/2012] [Accepted: 02/07/2013] [Indexed: 02/02/2023]
Affiliation(s)
- Karlie A. Neilson
- Department of Chemistry and Biomolecular Sciences; Macquarie University; New South Wales; Australia
| | - Andrew P. Scafaro
- Department of Biological Sciences, Macquarie University; New South Wales Australia
| | - Joel M. Chick
- Department of Cell Biology, Harvard Medical School; MA USA
| | - Iniga S. George
- Department of Chemistry and Biomolecular Sciences; Macquarie University; New South Wales; Australia
| | - Steven C. Van Sluyter
- Department of Chemistry and Biomolecular Sciences; Macquarie University; New South Wales; Australia
| | - Steven P. Gygi
- Department of Cell Biology, Harvard Medical School; MA USA
| | - Brian J. Atwell
- Department of Biological Sciences, Macquarie University; New South Wales Australia
| | - Paul A. Haynes
- Department of Chemistry and Biomolecular Sciences; Macquarie University; New South Wales; Australia
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22
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Scafaro AP, Yamori W, Carmo-Silva AE, Salvucci ME, von Caemmerer S, Atwell BJ. Rubisco activity is associated with photosynthetic thermotolerance in a wild rice (Oryza meridionalis). Physiol Plant 2012; 146:99-109. [PMID: 22324885 DOI: 10.1111/j.1399-3054.2012.01597.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Oryza meridionalis is a wild species of rice, endemic to tropical Australia. It shares a significant genome homology with the common domesticated rice Oryza sativa. Exploiting the fact that the two species are highly related but O. meridionalis has superior heat tolerance, experiments were undertaken to identify the impact of temperature on key events in photosynthesis. At an ambient CO(2) partial pressure of 38 Pa and irradiance of 1500 µmol quanta m(-2) s(-1), the temperature optimum of photosynthesis was 33.7 ± 0.8°C for O. meridionalis, significantly higher than the 30.6 ± 0.7°C temperature optimum of O. sativa. To understand the basis for this difference, we measured gas exchange and rubisco activation state between 20 and 42°C and modeled the response to determine the rate-limiting steps of photosynthesis. The temperature response of light respiration (R(light)) and the CO(2) compensation point in the absence of respiration (Γ(*)) were determined and found to be similar for the two species. C3 photosynthesis modeling showed that despite the difference in susceptibility to high temperature, both species had a similar temperature-dependent limitation to photosynthesis. Both rice species were limited by ribulose-1,5-bisphosphate (RuBP) regeneration at temperatures of 25 and 30°C but became RuBP carboxylation limited at 35 and 40°C. The activation state of rubisco in O. meridionalis was more stable at higher temperatures, explaining its greater heat tolerance compared with O. sativa.
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Affiliation(s)
- Andrew P Scafaro
- Department of Biological Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
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Scafaro AP, Von Caemmerer S, Evans JR, Atwell BJ. Temperature response of mesophyll conductance in cultivated and wild Oryza species with contrasting mesophyll cell wall thickness. Plant Cell Environ 2011; 34:1999-2008. [PMID: 21752031 DOI: 10.1111/j.1365-3040.2011.02398.x] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
A critical component of photosynthetic capacity is the conductance of CO(2) from intercellular airspaces to the sites of CO(2) fixation in the stroma of chloroplasts, termed mesophyll conductance (g(m)). Leaf anatomy has been identified as an important determinant of g(m). There are few studies of the temperature response of g(m) and none has examined the implications of leaf anatomy. Hence, we compared a cultivar of Oryza sativa with two wild Oryza relatives endemic to the hot northern savannah of Australia, namely Oryza meridionalis and Oryza australiensis. All three species had similar leaf anatomical properties, except that the wild relatives had significantly thicker mesophyll cell walls than O. sativa. Thicker mesophyll cell walls in the wild rice species are likely to have contributed to the reduction in g(m) , which was associated with a greater drawdown of CO(2) into chloroplasts (C(i) -C(c) ) compared with O. sativa. Mesophyll conductance increased at higher temperatures, whereas the rate of CO(2) assimilation was relatively stable between 20 and 40 °C. Consequently, C(i) -C(c) decreased for all three species as temperature increased.
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Affiliation(s)
- Andrew P Scafaro
- Department of Biological Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
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Abstract
Oryza meridionalis Ng. is a wild relative of Oryza sativa L. found throughout northern Australia where temperatures regularly exceed 35 degrees C in the monsoon growing season. Heat tolerance in O. meridionalis was established by comparing leaf elongation and photosynthetic rates at 45 degrees C with plants maintained at 27 degrees C. By comparison with O. sativa ssp. japonica cv. Amaroo, O. meridionalis was heat tolerant. Elongation rates of the third leaf of O. meridionalis declined by 47% over 24 h at 45 degrees C compared with a 91% decrease for O. sativa. Net photosynthesis was significantly higher in O. sativa at 27 degrees C whereas the two species had the same assimilation rates at 45 degrees C. The leaf proteome and expression levels of individual heat-responsive genes provided insight into the heat response of O. meridionalis. After 24 h of heat exposure, many enzymes involved in the Calvin Cycle were more abundant, while mRNA of their genes generally decreased. Ferredoxin-NADP(H) oxidoreductase, a key enzyme in photosynthetic electron transport had both reduced abundance and gene expression, suggesting light reactions were highly susceptible to heat stress. Rubisco activase was strongly up-regulated after 24 h of heat, with the large isoform having the largest relative increase in protein abundance and a significant increase in gene expression. The protective proteins Cpn60, Hsp90, and Hsp70 all increased in both protein abundance and gene expression. A thiamine biosynthesis protein (THI1), previously shown to act protectively against stress, increased in abundance during heat, even as thiamine levels fell in O. meridionalis.
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Affiliation(s)
- Andrew P. Scafaro
- Department of Biological Sciences, Macquarie University, NSW 2109, Australia
| | - Paul A. Haynes
- Department of Chemistry and Biomolecular Sciences, Macquarie University, NSW 2109, Australia
| | - Brian J. Atwell
- Department of Biological Sciences, Macquarie University, NSW 2109, Australia
- To whom correspondence should be addressed: E-mail:
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