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Smith K, Strand DD, Walker BJ. Evaluating the contribution of plant metabolic pathways in the light to the ATP:NADPH demand using a meta-analysis of isotopically non-stationary metabolic flux analyses. PHOTOSYNTHESIS RESEARCH 2024:10.1007/s11120-024-01106-5. [PMID: 38874662 DOI: 10.1007/s11120-024-01106-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2024] [Accepted: 06/06/2024] [Indexed: 06/15/2024]
Abstract
Balancing the ATP: NADPH demand from plant metabolism with supply from photosynthesis is essential for preventing photodamage and operating efficiently, so understanding its drivers is important for integrating metabolism with the light reactions of photosynthesis and for bioengineering efforts that may radically change this demand. It is often assumed that the C3 cycle and photorespiration consume the largest amount of ATP and reductant in illuminated leaves and as a result mostly determine the ATP: NADPH demand. However, the quantitative extent to which other energy consuming metabolic processes contribute in large ways to overall ATP: NADPH demand remains unknown. Here, we used the metabolic flux networks of numerous recently published isotopically non-stationary metabolic flux analyses (INST-MFA) to evaluate flux through the C3 cycle, photorespiration, the oxidative pentose phosphate pathway, the tricarboxylic acid cycle, and starch/sucrose synthesis and characterize broad trends in the demand of energy across different pathways and compartments as well as in the overall ATP:NADPH demand. These data sets include a variety of species including Arabidopsis thaliana, Nicotiana tabacum, and Camelina sativa as well as varying environmental factors including high/low light, day length, and photorespiratory levels. Examining these datasets in aggregate reveals that ultimately the bulk of the energy flux occurred in the C3 cycle and photorespiration, however, the energy demand from these pathways did not determine the ATP: NADPH demand alone. Instead, a notable contribution was revealed from starch and sucrose synthesis which might counterbalance photorespiratory demand and result in fewer adjustments in mechanisms which balance the ATP deficit.
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Affiliation(s)
- Kaila Smith
- Michigan State Unversity - Department of Energy, Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, USA
- Department of Plant Biology, Michigan State University, East Lansing, MI, 48824, USA
- Plant Biotechnology for Health and Sustainability Program, Michigan State University, East Lansing, MI, 48824, USA
| | - Deserah D Strand
- Michigan State Unversity - Department of Energy, Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, USA
- Department of Plant Biology, Michigan State University, East Lansing, MI, 48824, USA
| | - Berkley J Walker
- Michigan State Unversity - Department of Energy, Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, USA.
- Department of Plant Biology, Michigan State University, East Lansing, MI, 48824, USA.
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Zhang Y, Kaiser E, Dutta S, Sharkey TD, Marcelis LFM, Li T. Short-term salt stress reduces photosynthetic oscillations under triose phosphate utilization limitation in tomato. JOURNAL OF EXPERIMENTAL BOTANY 2024; 75:2994-3008. [PMID: 38436737 DOI: 10.1093/jxb/erae089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Accepted: 03/02/2024] [Indexed: 03/05/2024]
Abstract
Triose phosphate utilization (TPU) limitation is one of the three biochemical limitations of photosynthetic CO2 assimilation rate in C3 plants. Under TPU limitation, abrupt and large transitions in light intensity cause damped oscillations in photosynthesis. When plants are salt-stressed, photosynthesis is often down-regulated particularly under dynamic light intensity, but how salt stress affects TPU-related dynamic photosynthesis is still unknown. To elucidate this, tomato (Solanum lycopersicum) was grown with and without sodium chloride (NaCl, 100 mM) stress for 13 d. Under high CO2 partial pressure, rapid increases in light intensity caused profound photosynthetic oscillations. Salt stress reduced photosynthetic oscillations in leaves initially under both low- and high-light conditions and reduced the duration of oscillations by about 2 min. Besides, salt stress increased the threshold for CO2 partial pressure at which oscillations occurred. Salt stress increased TPU capacity without affecting Rubisco carboxylation and electron transport capacity, indicating the up-regulation of end-product synthesis capacity in photosynthesis. Thus salt stress may reduce photosynthetic oscillations by decreasing leaf internal CO2 partial pressure and/or increasing TPU capacity. Our results provide new insights into how salt stress modulates dynamic photosynthesis as controlled by CO2 availability and end-product synthesis.
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Affiliation(s)
- Yuqi Zhang
- Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Elias Kaiser
- Horticulture and Product Physiology, Department of Plant Sciences, Wageningen University, Wageningen, the Netherlands
| | - Satadal Dutta
- Department of Precision and Microsystems Engineering, Faculty of 3ME, TU Delft, Delft, the Netherlands
| | - Thomas D Sharkey
- MSU-DOE Plant Research Laboratory, East Lansing, MI 48824, USA
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA
- Plant Resilience Institute, Michigan State University, East Lansing, MI 48824, USA
| | - Leo F M Marcelis
- Horticulture and Product Physiology, Department of Plant Sciences, Wageningen University, Wageningen, the Netherlands
| | - Tao Li
- Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences, Beijing, China
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Tejera-Nieves M, Seong DY, Reist L, Walker BJ. The Dynamic Assimilation Technique measures photosynthetic CO2 response curves with similar fidelity to steady-state approaches in half the time. JOURNAL OF EXPERIMENTAL BOTANY 2024; 75:2819-2828. [PMID: 38366564 PMCID: PMC11103103 DOI: 10.1093/jxb/erae057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Accepted: 02/14/2024] [Indexed: 02/18/2024]
Abstract
The net CO2 assimilation (A) response to intercellular CO2 concentration (Ci) is a fundamental measurement in photosynthesis and plant physiology research. The conventional A/Ci protocols rely on steady-state measurements and take 15-40 min per measurement, limiting data resolution or biological replication. Additionally, there are several CO2 protocols employed across the literature, without clear consensus as to the optimal protocol or systematic biases in their estimations. We compared the non-steady-state Dynamic Assimilation Technique (DAT) protocol and the three most used CO2 protocols in steady-state measurements, and tested whether different CO2 protocols lead to systematic differences in estimations of the biochemical limitations to photosynthesis. The DAT protocol reduced the measurement time by almost half without compromising estimation accuracy or precision. The monotonic protocol was the fastest steady-state method. Estimations of biochemical limitations to photosynthesis were very consistent across all CO2 protocols, with slight differences in Rubisco carboxylation limitation. The A/Ci curves were not affected by the direction of the change of CO2 concentration but rather the time spent under triose phosphate utilization (TPU)-limited conditions. Our results suggest that the maximum rate of Rubisco carboxylation (Vcmax), linear electron flow for NADPH supply (J), and TPU measured using different protocols within the literature are comparable, or at least not systematically different based on the measurement protocol used.
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Affiliation(s)
- Mauricio Tejera-Nieves
- MSU-DOE Plant Research Laboratory, Michigan State University, 612 Wilson Rd, East Lansing, MI 48824, USA
- Great Lakes Bioenergy Research Center, Michigan State University, 1129 Farm Ln, East Lansing, MI 48824, USA
| | - Do Young Seong
- Department of Medical Informatics, College of Medicine, Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul 06591, Republic of Korea
| | - Lucas Reist
- Department of Biochemistry & Molecular Biology, Michigan State University, Molecular Plant Sciences Building, 1066 Bogue Street, East Lansing, MI 48824, USA
| | - Berkley J Walker
- MSU-DOE Plant Research Laboratory, Michigan State University, 612 Wilson Rd, East Lansing, MI 48824, USA
- Great Lakes Bioenergy Research Center, Michigan State University, 1129 Farm Ln, East Lansing, MI 48824, USA
- Department of Plant Biology, Michigan State University, 612 Wilson Rd, East Lansing, MI 48824, USA
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Degen GE, Pastorelli F, Johnson MP. Proton Gradient Regulation 5 is required to avoid photosynthetic oscillations during light transitions. JOURNAL OF EXPERIMENTAL BOTANY 2024; 75:947-961. [PMID: 37891008 DOI: 10.1093/jxb/erad428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Accepted: 10/27/2023] [Indexed: 10/29/2023]
Abstract
The production of ATP and NADPH by the light reactions of photosynthesis and their consumption by the Calvin-Benson-Bassham (CBB) cycle and other downstream metabolic reactions requires careful regulation. Environmental shifts perturb this balance, leading to photo-oxidative stress and losses in CO2 assimilation. Imbalances in the production and consumption of ATP and NADPH manifest themselves as transient instability in the chlorophyll fluorescence, P700, electrochromic shift, and CO2 uptake signals recorded on leaves. These oscillations can be induced in wild-type plants by sudden shifts in CO2 concentration or light intensity; however, mutants exhibiting increased oscillatory behaviour have yet to be reported. This has precluded an understanding of the regulatory mechanisms employed by plants to suppress oscillations. Here we show that the Arabidopsis pgr5 mutant, which is deficient in Proton Gradient Regulation 5 (PGR5)-dependent cyclic electron transfer (CET), exhibits increased oscillatory behaviour. In contrast, mutants lacking the NADH-dehydrogenase-like-dependent CET are largely unaffected. The absence of oscillations in the hope2 mutant which, like pgr5, lacks photosynthetic control and exhibits high ATP synthase conductivity, ruled out loss of these photoprotective mechanisms as causes. Instead, we observed slower formation of the proton motive force and, by inference, ATP synthesis in pgr5 following environmental perturbation, leading to the transient reduction of the electron transfer chain and photosynthetic oscillations. PGR5-dependent CET therefore plays a major role in damping the effect of environmental perturbations on photosynthesis to avoid losses in CO2 fixation.
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Affiliation(s)
- Gustaf E Degen
- Plants, Photosynthesis & Soil, School of Biosciences, University of Sheffield, Sheffield, UK
| | - Federica Pastorelli
- Plants, Photosynthesis & Soil, School of Biosciences, University of Sheffield, Sheffield, UK
| | - Matthew P Johnson
- Plants, Photosynthesis & Soil, School of Biosciences, University of Sheffield, Sheffield, UK
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Shikanai T. Research on photosynthetic oscillations supports the classical concept of cyclic electron transport producing ATP. JOURNAL OF EXPERIMENTAL BOTANY 2024; 75:667-669. [PMID: 38307515 DOI: 10.1093/jxb/erae015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2024]
Abstract
This article comments on:
Degen GE, Pastorelli F, Johnson MP. 2024. Proton Gradient Regulation 5 is required to avoid photosynthetic oscillations during light transitions. Journal of Experimental Botany 75, 947–961.
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Affiliation(s)
- Toshiharu Shikanai
- Kyoto University-Graduate School of Science, Department of Botany, Kyoto, 606-8502, Japan
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Gregory LM, Roze LV, Walker BJ. Increased activity of core photorespiratory enzymes and CO 2 transfer conductances are associated with higher and more optimal photosynthetic rates under elevated temperatures in the extremophile Rhazya stricta. PLANT, CELL & ENVIRONMENT 2023; 46:3704-3720. [PMID: 37667571 DOI: 10.1111/pce.14711] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Revised: 06/26/2023] [Accepted: 08/23/2023] [Indexed: 09/06/2023]
Abstract
Increase photorespiration and optimising intrinsic water use efficiency are unique challenges to photosynthetic carbon fixation at elevated temperatures. To determine how plants can adapt to facilitate high rates of photorespiration at elevated temperatures while also maintaining water-use efficiency, we performed in-depth gas exchange and biochemical assays of the C3 extremophile, Rhazya stricta. These results demonstrate that R. stricta supports higher rates of photorespiration under elevated temperatures and that these higher rates of photorespiration correlate with increased activity of key photorespiratory enzymes; phosphoglycolate phosphatase and catalase. The increased photorespiratory enzyme activities may increase the overall capacity of photorespiration by reducing enzymatic bottlenecks and allowing minimal inhibitor accumulation under high photorespiratory rates. Additionally, we found the CO2 transfer conductances (stomatal and mesophyll) are re-allocated to increase the water-use efficiency in R. stricta but not necessarily the photosynthetic response to temperature. These results suggest important adaptive strategies in R. stricta that maintain photosynthetic rates under elevated temperatures with optimal water loss. The strategies found in R. stricta may inform breeding and engineering efforts in other C3 species to improve photosynthetic efficiency at high temperatures.
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Affiliation(s)
- Luke M Gregory
- Department of Energy-Plant Research Laboratory, Michigan State University, East Lansing, Michigan, USA
- Department of Plant Biology, Michigan State University, East Lansing, Michigan, USA
| | - Ludmila V Roze
- Department of Energy-Plant Research Laboratory, Michigan State University, East Lansing, Michigan, USA
| | - Berkley J Walker
- Department of Energy-Plant Research Laboratory, Michigan State University, East Lansing, Michigan, USA
- Department of Plant Biology, Michigan State University, East Lansing, Michigan, USA
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