Journal articles: 'Photorespiration'

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Peterhansel, Christoph, Ina Horst, Markus Niessen, Christian Blume, Rashad Kebeish, Sophia Kürkcüoglu, and Fritz Kreuzaler. "Photorespiration." Arabidopsis Book 8 (January 2010): e0130. http://dx.doi.org/10.1199/tab.0130.

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Peterhansel, Christoph, and Veronica G. Maurino. "Photorespiration Redesigned." Plant Physiology 155, no. 1 (October 12, 2010): 49–55. http://dx.doi.org/10.1104/pp.110.165019.

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Eckardt, Nancy A. "Photorespiration Revisited." Plant Cell 17, no. 8 (August 2005): 2139–41. http://dx.doi.org/10.1105/tpc.105.035873.

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Zheng, Kunpeng, Yu Bo, Yanda Bao, Xiaolei Zhu, Jian Wang, and Yu Wang. "A Machine Learning Model for Photorespiration Response to Multi-Factors." Horticulturae 7, no. 8 (July 21, 2021): 207. http://dx.doi.org/10.3390/horticulturae7080207.

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Photorespiration results in a large amount of leaf photosynthesis consumption. However, there are few studies on the response of photorespiration to multi-factors. In this study, a machine learning model for the photorespiration rate of cucumber leaves’ response to multi-factors was established. It provides a theoretical basis for studies related to photorespiration. Machine learning models of different methods were designed and compared. The photorespiration rate was expressed as the difference between the photosynthetic rate at 2% O2 and 21% O2 concentrations. The results show that the XGBoost models had the best fit performance with an explained variance score of 0.970 for both photosynthetic rate datasets measured using air and 2% O2, with mean absolute errors of 0.327 and 0.181, root mean square errors of 1.607 and 1.469, respectively, and coefficients of determination of 0.970 for both. In addition, this study indicates the importance of the features of temperature, humidity and the physiological status of the leaves for predicted results of photorespiration. The model established in this study performed well, with high accuracy and generalization ability. As a preferable exploration of the research on photorespiration rate simulation, it has theoretical significance and application prospects.

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Timm, Stefan, and Martin Hagemann. "Photorespiration—how is it regulated and how does it regulate overall plant metabolism?" Journal of Experimental Botany 71, no. 14 (April 10, 2020): 3955–65. http://dx.doi.org/10.1093/jxb/eraa183.

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Abstract Under the current atmospheric conditions, oxygenic photosynthesis requires photorespiration to operate. In the presence of low CO2/O2 ratios, ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) performs an oxygenase side reaction, leading to the formation of high amounts of 2-phosphoglycolate during illumination. Given that 2-phosphoglycolate is a potent inhibitor of photosynthetic carbon fixation, it must be immediately removed through photorespiration. The core photorespiratory cycle is orchestrated across three interacting subcellular compartments, namely chloroplasts, peroxisomes, and mitochondria, and thus cross-talks with a multitude of other cellular processes. Over the past years, the metabolic interaction of photorespiration and photosynthetic CO2 fixation has attracted major interest because research has demonstrated the enhancement of C3 photosynthesis and growth through the genetic manipulation of photorespiration. However, to optimize future engineering approaches, it is also essential to improve our current understanding of the regulatory mechanisms of photorespiration. Here, we summarize recent progress regarding the steps that control carbon flux in photorespiration, eventually involving regulatory proteins and metabolites. In this regard, both genetic engineering and the identification of various layers of regulation point to glycine decarboxylase as the key enzyme to regulate and adjust the photorespiratory carbon flow. Potential implications of the regulation of photorespiration for acclimation to environmental changes along with open questions are also discussed.

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Roell, Marc-Sven, Lennart Schada von Borzyskowski, Philipp Westhoff, Anastasija Plett, Nicole Paczia, Peter Claus, Urte Schlueter, Tobias J. Erb, and Andreas P. M. Weber. "A synthetic C4 shuttle via the β-hydroxyaspartate cycle in C3 plants." Proceedings of the National Academy of Sciences 118, no. 21 (May 17, 2021): e2022307118. http://dx.doi.org/10.1073/pnas.2022307118.

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Plants depend on the enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) for CO2 fixation. However, especially in C3 plants, photosynthetic yield is reduced by formation of 2-phosphoglycolate, a toxic oxygenation product of Rubisco, which needs to be recycled in a high-flux–demanding metabolic process called photorespiration. Canonical photorespiration dissipates energy and causes carbon and nitrogen losses. Reducing photorespiration through carbon-concentrating mechanisms, such as C4 photosynthesis, or bypassing photorespiration through metabolic engineering is expected to improve plant growth and yield. The β-hydroxyaspartate cycle (BHAC) is a recently described microbial pathway that converts glyoxylate, a metabolite of plant photorespiration, into oxaloacetate in a highly efficient carbon-, nitrogen-, and energy-conserving manner. Here, we engineered a functional BHAC in plant peroxisomes to create a photorespiratory bypass that is independent of 3-phosphoglycerate regeneration or decarboxylation of photorespiratory precursors. While efficient oxaloacetate conversion in Arabidopsis thaliana still masks the full potential of the BHAC, nitrogen conservation and accumulation of signature C4 metabolites demonstrate the proof of principle, opening the door to engineering a photorespiration-dependent synthetic carbon–concentrating mechanism in C3 plants.

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Shi, Xiaoxiao, and Arnold Bloom. "Photorespiration: The Futile Cycle?" Plants 10, no. 5 (May 1, 2021): 908. http://dx.doi.org/10.3390/plants10050908.

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Photorespiration, or C2 photosynthesis, is generally considered a futile cycle that potentially decreases photosynthetic carbon fixation by more than 25%. Nonetheless, many essential processes, such as nitrogen assimilation, C1 metabolism, and sulfur assimilation, depend on photorespiration. Most studies of photosynthetic and photorespiratory reactions are conducted with magnesium as the sole metal cofactor despite many of the enzymes involved in these reactions readily associating with manganese. Indeed, when manganese is present, the energy efficiency of these reactions may improve. This review summarizes some commonly used methods to quantify photorespiration, outlines the influence of metal cofactors on photorespiratory enzymes, and discusses why photorespiration may not be as wasteful as previously believed.

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Wingler, Astrid, Peter J. Lea, W. Paul Quick, and Richard C. Leegood. "Photorespiration: metabolic pathways and their role in stress protection." Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences 355, no. 1402 (October 29, 2000): 1517–29. http://dx.doi.org/10.1098/rstb.2000.0712.

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Photorespiration results from the oxygenase reaction catalysed by ribulose–1,5–bisphosphate carboxylase/oxygenase. In this reaction glycollate–2–phosphate is produced and subsequently metabolized in the photorespiratory pathway to form the Calvin cycle intermediate glycerate–3–phosphate. During this metabolic process, CO 2 and NH 3 are produced and ATP and reducing equivalents are consumed, thus making photorespiration a wasteful process. However, precisely because of this inefficiency, photorespiration could serve as an energy sink preventing the overreduction of the photosynthetic electron transport chain and photoinhibition, especially under stress conditions that lead to reduced rates of photosynthetic CO 2 assimilation. Furthermore, photorespiration provides metabolites for other metabolic processes, e.g. glycine for the synthesis of glutathione, which is also involved in stress protection. In this review, we describe the use of photorespiratory mutants to study the control and regulation of photorespiratory pathways. In addition, we discuss the possible role of photorespiration under stress conditions, such as drought, high salt concentrations and high light intensities encountered by alpine plants.

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Badger, Murray R., Hossein Fallahi, Sarah Kaines, and Shunichi Takahashi. "Chlorophyll fluorescence screening of Arabidopsis thaliana for CO2 sensitive photorespiration and photoinhibition mutants." Functional Plant Biology 36, no. 11 (2009): 867. http://dx.doi.org/10.1071/fp09199.

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Exposure of Arabidopsis thaliana (L.) photorespiration mutants to air leads to a rapid decline in the Fv/Fm chlorophyll fluorescence parameter, reflecting a decline in PSII function and an onset of photoinhibition. This paper demonstrates that chlorophyll fluorescence imaging of Fv/Fm can be used as an easy and efficient means of detecting Arabidopsis mutants that are impaired in various aspects of photorespiration. This screen was developed to be sensitive and high throughput by the use of exposure to zero CO2 conditions and the use of array grids of 1-week-old Arabidopsis seedlings as the starting material for imaging. Using this procedure, we screened ~25 000 chemically mutagenised M2 Arabidopsis seeds and recovered photorespiration phenotypes (reduction in Fv/Fm at low CO2) at a frequency of ~4 per 1000 seeds. In addition, we also recovered mutants that showed reduced Fv/Fm at high CO2. Of this group, we detected a novel ‘reverse photorespiration’ phenotype that showed a high CO2 dependent reduction in Fv/Fm. This chlorophyll fluorescence screening technique promises to reveal novel mutants associated with photorespiration and photoinhibition.

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Shi, Qi, Hu Sun, Stefan Timm, Shibao Zhang, and Wei Huang. "Photorespiration Alleviates Photoinhibition of Photosystem I under Fluctuating Light in Tomato." Plants 11, no. 2 (January 12, 2022): 195. http://dx.doi.org/10.3390/plants11020195.

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Fluctuating light (FL) is a typical natural light stress that can cause photodamage to photosystem I (PSI). However, the effect of growth light on FL-induced PSI photoinhibition remains controversial. Plants grown under high light enhance photorespiration to sustain photosynthesis, but the contribution of photorespiration to PSI photoprotection under FL is largely unknown. In this study, we examined the photosynthetic performance under FL in tomato (Lycopersicon esculentum) plants grown under high light (HL-plants) and moderate light (ML-plants). After an abrupt increase in illumination, the over-reduction of PSI was lowered in HL-plants, resulting in a lower FL-induced PSI photoinhibition. HL-plants displayed higher capacities for CO2 fixation and photorespiration than ML-plants. Within the first 60 s after transition from low to high light, PSII electron transport was much higher in HL-plants, but the gross CO2 assimilation rate showed no significant difference between them. Therefore, upon a sudden increase in illumination, the difference in PSII electron transport between HL- and ML-plants was not attributed to the Calvin–Benson cycle but was caused by the change in photorespiration. These results indicated that the higher photorespiration in HL-plants enhanced the PSI electron sink downstream under FL, which mitigated the over-reduction of PSI and thus alleviated PSI photoinhibition under FL. Taking together, we here for the first time propose that photorespiration acts as a safety valve for PSI photoprotection under FL.

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Bräutigam, Andrea, and Udo Gowik. "Photorespiration connects C3and C4photosynthesis." Journal of Experimental Botany 67, no. 10 (February 22, 2016): 2953–62. http://dx.doi.org/10.1093/jxb/erw056.

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12

Douce, Roland, and Michel Neuburger. "Biochemical dissection of photorespiration." Current Opinion in Plant Biology 2, no. 3 (June 1999): 214–22. http://dx.doi.org/10.1016/s1369-5266(99)80038-7.

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13

Hodges, M., M. Jossier, E. Boex-Fontvieille, and G. Tcherkez. "Protein phosphorylation and photorespiration." Plant Biology 15, no. 4 (March 18, 2013): 694–706. http://dx.doi.org/10.1111/j.1438-8677.2012.00719.x.

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14

Carlos, Pimentel,. "Photorespiration: a Multipurpose Process." Environmental Sciences and Ecology: Current Research (ESECR 4, no. 4 (October 26, 2023): 1–2. http://dx.doi.org/10.54026/esecr/1098.

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Ye, Jie, Weifang Chen, Longwei Feng, Genzhong Liu, Ying Wang, Hanxia Li, Zhibiao Ye, and Yuyang Zhang. "The chaperonin 60 protein SlCpn60α1 modulates photosynthesis and photorespiration in tomato." Journal of Experimental Botany 71, no. 22 (September 11, 2020): 7224–40. http://dx.doi.org/10.1093/jxb/eraa418.

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Abstract Photosynthesis, an indispensable biological process of plants, produces organic substances for plant growth, during which photorespiration occurs to oxidize carbohydrates to achieve homeostasis. Although the molecular mechanism underlying photosynthesis and photorespiration has been widely explored, the crosstalk between the two processes remains largely unknown. In this study, we isolated and characterized a T-DNA insertion mutant of tomato (Solanum lycopersicum) named yellow leaf (yl) with yellowish leaves, retarded growth, and chloroplast collapse that hampered both photosynthesis and photorespiration. Genetic and expression analyses demonstrated that the phenotype of yl was caused by a loss-of-function mutation resulting from a single-copy T-DNA insertion in chaperonin 60α1 (SlCPN60α1). SlCPN60α1 showed high expression levels in leaves and was located in both chloroplasts and mitochondria. Silencing of SlCPN60α1using virus-induced gene silencing and RNA interference mimicked the phenotype of yl. Results of two-dimensional electrophoresis and yeast two-hybrid assays suggest that SlCPN60α1 potentially interacts with proteins that are involved in chlorophyll synthesis, photosynthetic electron transport, and the Calvin cycle, and further affect photosynthesis. Moreover, SlCPN60α1 directly interacted with serine hydroxymethyltransferase (SlSHMT1) in mitochondria, thereby regulating photorespiration in tomato. This study outlines the importance of SlCPN60α1 for both photosynthesis and photorespiration, and provides molecular insights towards plant genetic improvement.

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Liu, Liyuan, Zhenxing Wang, Xianhua Zhao, Lijun Nan, Hailong Nan, Shan Wang, and Hua Li. "Effects of different photorespiration inhibitors on photosynthetic characteristics and berry quality of Vitis amurensis Rupr." Canadian Journal of Plant Science 95, no. 2 (March 2015): 417–26. http://dx.doi.org/10.4141/cjps-2014-155.

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Liu, L., Wang, Z., Zhao, X., Nan, L., Nan, H., Wang, S. and Li, H. 2015. Effects of different photorespiration inhibitors on photosynthetic characteristics and berry quality of Vitis amurensis Rupr. Can. J. Plant Sci. 95: 417–426. The effects of two photorespiration inhibitors on photosynthetic characteristics and berry quality of Vitis amurensis Rupr. were studied. The experiments used V. amurensis variety ‘Shuang hong’ as the experimental grape, NaHSO3 (sodium bisulfite) and isoniazide (INH) as the photorespiration inhibitors with three different spray concentrations, respectively. Results show that both photorespiration inhibitors improved the soluble solids (SS) contents and SS/total acid (TA) ratios (except the 350 mg L−1 INH treatment) in V. amurensis berries; two inhibitors can also improve the concentrations of glucose, sucrose, arabinose, lactose as well as monosaccharides (MS) and MS+disaccharides (DS) contents, and at the same time decrease the TA contents in V. amurensis berries. Meanwhile, all NaHSO3 treatments had higher SS, SS/TA, glucose, and sucrose than treatments with the same concentrations of INH. However, the arabinose contents in all the INH treatments were higher than those in NaHSO3 treatments at the same concentrations. Compared with INH treatments, NaHSO3 were better at increasing net photosythesis rate (Pn), Rubisco carboxylation efficiency (CE), intercellular CO2 concentration (Ci) and decreasing photorespiration rate (Pr). However, the effects of NaHSO3 and INH on fluorescent characteristics of V. amurensis leaves were not significant. The fact that maximal values for photochemical efficiency of photosystem II complex (PSII) in the dark (Fv/Fm) in this study were large indicate that both NaHSO3 and INH had positive effects on chlorophyll fluorescence of V. amurensis leaves, which meant they had the ability to release surplus light energy and mitigate photoinhibition by inhibiting photorespiration at all three concentrations. Comprehensive analysis clearly indicates that NaHSO3 had better effects on photorespiration inhibition and fluorescent characteristics, and improved photosynthesis and the quality of V. amurensis grape berries, especially at 250 mg L−1.

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Wendler, Ch, and A. Wild. "Effect of Phosphinothricin (Glufosinate) on Photosynthesis and Photorespiration." Zeitschrift für Naturforschung C 45, no. 5 (May 1, 1990): 535–37. http://dx.doi.org/10.1515/znc-1990-0540.

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Phosphinothricin (PPT) causes a rapid inhibition of photosynthesis under atmospheric conditions (400 ppm CO2, 21% O2). However, under conditions (1000 ppm CO2, 2% O2) under which photorespiration cannot occur, there is no or only a very low rate of photosynthesis inhibition by phosphinothricin. Under both conditions, a strong NH4+-accumulation is apparent caused through the inhibition of glutamine synthetase by phosphinothricin. This indicates, that NH4+-accumulation cannot be the primary cause for photosynthesis inhibition by phosphinothricin, but a process in connexion with photorespiration plays a central role. Through the lack of amino donors, the transamination of glyoxylate to glycine in photorespiration cannot take place. PPT causes a great decrease in glutamine, glutamate, aspartate, serine, and glycine. Following addition of these amino acids to PPT, there is a decrease in photosynthesis inhibition by PPT. With the addition of glutamine or glutamate to PPT no decrease in serine and glycine is detected, because the transamination of glyoxylate to glycine in photorespiration can occur.

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Timm, Stefan. "The impact of photorespiration on plant primary metabolism through metabolic and redox regulation." Biochemical Society Transactions 48, no. 6 (December 10, 2020): 2495–504. http://dx.doi.org/10.1042/bst20200055.

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Photorespiration is an inevitable trait of all oxygenic phototrophs, being the only known metabolic route that converts the inhibitory side-product of Rubisco's oxygenase activity 2-phosphoglycolate (2PG) back into the Calvin–Benson (CB) cycle's intermediate 3-phosphoglycerate (3PGA). Through this function of metabolite repair, photorespiration is able to protect photosynthetic carbon assimilation from the metabolite intoxication that would occur in the present-day oxygen-rich atmosphere. In recent years, much plant research has provided compelling evidence that photorespiration safeguards photosynthesis and engages in cross-talk with a number of subcellular processes. Moreover, the potential of manipulating photorespiration to increase the photosynthetic yield potential has been demonstrated in several plant species. Considering this multifaceted role, it is tempting to presume photorespiration itself is subject to a suite of regulation mechanisms to eventually exert a regulatory impact on other processes, and vice versa. The identification of potential pathway interactions and underlying regulatory aspects has been facilitated via analysis of the photorespiratory mutant phenotype, accompanied by the emergence of advanced omics’ techniques and biochemical approaches. In this mini-review, I focus on the identification of enzymatic steps which control the photorespiratory flux, as well as levels of transcriptional, posttranslational, and metabolic regulation. Most importantly, glycine decarboxylase (GDC) and 2PG are identified as being key photorespiratory determinants capable of controlling photorespiratory flux and communicating with other branches of plant primary metabolism.

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Wang, Zi, Yetao Wang, Yukun Wang, Haotian Li, Zhiting Wen, and Xin Hou. "HPR1 Is Required for High Light Intensity Induced Photorespiration in Arabidopsis thaliana." International Journal of Molecular Sciences 23, no. 8 (April 18, 2022): 4444. http://dx.doi.org/10.3390/ijms23084444.

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High light intensity as one of the stresses could lead to generation of large amounts of reactive oxygen species (ROS) in plants, resulting in severe plant growth retardation. The photorespiration metabolism plays an important role in producing and removing a variety of ROS, maintaining the dynamic balance of the redox reaction, and preventing photoinhibition. Arabidopsis hydroxypyruvate reductase 1 (HPR1) is a primary metabolic enzyme in the photorespiration cycle. However, the role of HPR1 in plants response to high light is not clear. Here, we found that the expression of HPR1 could be induced by high light intensity. The growth and photosynthetic capacity of hpr1 mutants are seriously affected under high light intensity. The absence of HPR1 suppresses the rates of photorepair of Photosystem II (PSII), aggravates the production of ROS, and accelerates photorespiration rates. Moreover, the activity of ROS scavenging enzymes in the hpr1 mutants is significantly higher. These results indicate that HPR1 is involved in plant response to high light intensity and is essential for maintaining the dynamic balance of ROS and photorespiration.

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Trudeau, Devin L., Christian Edlich-Muth, Jan Zarzycki, Marieke Scheffen, Moshe Goldsmith, Olga Khersonsky, Ziv Avizemer, et al. "Design and in vitro realization of carbon-conserving photorespiration." Proceedings of the National Academy of Sciences 115, no. 49 (November 20, 2018): E11455—E11464. http://dx.doi.org/10.1073/pnas.1812605115.

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Photorespiration recycles ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) oxygenation product, 2-phosphoglycolate, back into the Calvin Cycle. Natural photorespiration, however, limits agricultural productivity by dissipating energy and releasing CO2. Several photorespiration bypasses have been previously suggested but were limited to existing enzymes and pathways that release CO2. Here, we harness the power of enzyme and metabolic engineering to establish synthetic routes that bypass photorespiration without CO2 release. By defining specific reaction rules, we systematically identified promising routes that assimilate 2-phosphoglycolate into the Calvin Cycle without carbon loss. We further developed a kinetic–stoichiometric model that indicates that the identified synthetic shunts could potentially enhance carbon fixation rate across the physiological range of irradiation and CO2, even if most of their enzymes operate at a tenth of Rubisco’s maximal carboxylation activity. Glycolate reduction to glycolaldehyde is essential for several of the synthetic shunts but is not known to occur naturally. We, therefore, used computational design and directed evolution to establish this activity in two sequential reactions. An acetyl-CoA synthetase was engineered for higher stability and glycolyl-CoA synthesis. A propionyl-CoA reductase was engineered for higher selectivity for glycolyl-CoA and for use of NADPH over NAD+, thereby favoring reduction over oxidation. The engineered glycolate reduction module was then combined with downstream condensation and assimilation of glycolaldehyde to ribulose 1,5-bisphosphate, thus providing proof of principle for a carbon-conserving photorespiration pathway.

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Furutani, Riu, Amane Makino, Yuij Suzuki, Shinya Wada, Ginga Shimakawa, and Chikahiro Miyake. "Intrinsic Fluctuations in Transpiration Induce Photorespiration to Oxidize P700 in Photosystem I." Plants 9, no. 12 (December 12, 2020): 1761. http://dx.doi.org/10.3390/plants9121761.

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Upon exposure to environmental stress, the primary electron donor in photosystem I (PSI), P700, is oxidized to suppress the production of reactive oxygen species that could oxidatively inactivate the function of PSI. The illumination of rice leaves with actinic light induces intrinsic fluctuations in the opening and closing of stomata, causing the net CO2 assimilation rate to fluctuate. We examined the effects of these intrinsic fluctuations on electron transport reactions. Under atmospheric O2 conditions (21 kPa), the effective quantum yield of photosystem II (PSII) (Y(II)) remained relatively high while the net CO2 assimilation rate fluctuated, which indicates the function of alternative electron flow. By contrast, under low O2 conditions (2 kPa), Y(II) fluctuated. These results suggest that photorespiration primarily drove the alternative electron flow. Photorespiration maintained the oxidation level of ferredoxin (Fd) throughout the fluctuation of the net CO2 assimilation rate. Moreover, the relative activity of photorespiration was correlated with both the oxidation level of P700 and the magnitude of the proton gradient across the thylakoid membrane in 21 kPa O2 conditions. These results show that photorespiration oxidized P700 by stimulating the proton gradient formation when CO2 assimilation was suppressed by stomatal closure.

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Wada, Shinya, Yuji Suzuki, and Chikahiro Miyake. "Photorespiration Enhances Acidification of the Thylakoid Lumen, Reduces the Plastoquinone Pool, and Contributes to the Oxidation of P700 at a Lower Partial Pressure of CO2 in Wheat Leaves." Plants 9, no. 3 (March 3, 2020): 319. http://dx.doi.org/10.3390/plants9030319.

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The oxidation of P700 in photosystem I (PSI) is a robust mechanism that suppresses the production of reactive oxygen species. We researched the contribution of photorespiration to the oxidation of P700 in wheat leaves. We analyzed the effects of changes in partial pressures of CO2 and O2 on photosynthetic parameters. The electron flux in photosynthetic linear electron flow (LEF) exhibited a positive linear relationship with an origin of zero against the dissipation rate (vH+) of electrochromic shift (ECS; ΔpH across thylakoid membrane), indicating that cyclic electron flow around PSI did not contribute to H+ usage in photosynthesis/photorespiration. The vH+ showed a positive linear relationship with an origin of zero against the H+ consumption rates in photosynthesis/photorespiration (JgH+). These two linear relationships show that the electron flow in LEF is very efficiently coupled with H+ usage in photosynthesis/photorespiration. Lowering the intercellular partial pressure of CO2 enhanced the oxidation of P700 with the suppression of LEF. Under photorespiratory conditions, the oxidation of P700 and the reduction of the plastoquinone pool were stimulated with a decrease in JgH+, compared to non-photorespiratory conditions. These results indicate that the reduction-induced suppression of electron flow (RISE) suppresses the reduction of oxidized P700 in PSI under photorespiratory conditions. Furthermore, under photorespiratory conditions, ECS was larger and H+ conductance was lower against JgH+ than those under non-photorespiratory conditions. These results indicate that photorespiration enhances RISE and ΔpH formation by lowering H+ conductance, both of which contribute to keeping P700 in a highly oxidized state.

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Bauwe, Hermann. "Recent developments in photorespiration research." Biochemical Society Transactions 38, no. 2 (March 22, 2010): 677–82. http://dx.doi.org/10.1042/bst0380677.

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Photorespiration is the light-dependent release of CO2 initiated by Rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase) during oxygenic photosynthesis. It occurs during the biochemical reactions of the photorespiratory C2 cycle, which is an ancillary metabolic process that allows photosynthesis to occur in oxygen-containing environments. Recent research has identified the genes for many plant photorespiratory enzymes, allowing precise functional analyses by reverse genetics. Similar studies with cyanobacteria disclosed the evolutionary origin of photorespiratory metabolism in these ancestors of plastids.

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Bauwe, Hermann, Martin Hagemann, and Alisdair R. Fernie. "Photorespiration: players, partners and origin." Trends in Plant Science 15, no. 6 (June 2010): 330–36. http://dx.doi.org/10.1016/j.tplants.2010.03.006.

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Leegood, Richard C. "A welcome diversion from photorespiration." Nature Biotechnology 25, no. 5 (May 2007): 539–40. http://dx.doi.org/10.1038/nbt0507-539.

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Timm, Stefan, Adriano Nunes-Nesi, Alexandra Florian, Marion Eisenhut, Katja Morgenthal, Markus Wirtz, Rüdiger Hell, et al. "Metabolite Profiling in Arabidopsisthaliana with Moderately Impaired Photorespiration Reveals Novel Metabolic Links and Compensatory Mechanisms of Photorespiration." Metabolites 11, no. 6 (June 15, 2021): 391. http://dx.doi.org/10.3390/metabo11060391.

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Photorespiration is an integral component of plant primary metabolism. Accordingly, it has been often observed that impairing the photorespiratory flux negatively impacts other cellular processes. In this study, the metabolic acclimation of the Arabidopsisthaliana wild type was compared with the hydroxypyruvate reductase 1 (HPR1; hpr1) mutant, displaying only a moderately reduced photorespiratory flux. Plants were analyzed during development and under varying photoperiods with a combination of non-targeted and targeted metabolome analysis, as well as 13C- and 14C-labeling approaches. The results showed that HPR1 deficiency is more critical for photorespiration during the vegetative compared to the regenerative growth phase. A shorter photoperiod seems to slowdown the photorespiratory metabolite conversion mostly at the glycerate kinase and glycine decarboxylase steps compared to long days. It is demonstrated that even a moderate impairment of photorespiration severely reduces the leaf-carbohydrate status and impacts on sulfur metabolism. Isotope labeling approaches revealed an increased CO2 release from hpr1 leaves, most likely occurring from enhanced non-enzymatic 3-hydroxypyruvate decarboxylation and a higher flux from serine towards ethanolamine through serine decarboxylase. Collectively, the study provides evidence that the moderate hpr1 mutant is an excellent tool to unravel the underlying mechanisms governing the regulation of metabolic linkages of photorespiration with plant primary metabolism.

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Bapatla, Ramesh B., Deepak Saini, Vetcha Aswani, Pidakala Rajsheel, Bobba Sunil, Stefan Timm, and Agepati S. Raghavendra. "Modulation of Photorespiratory Enzymes by Oxidative and Photo-Oxidative Stress Induced by Menadione in Leaves of Pea (Pisum sativum)." Plants 10, no. 5 (May 15, 2021): 987. http://dx.doi.org/10.3390/plants10050987.

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Photorespiration, an essential component of plant metabolism, is concerted across four subcellular compartments, namely, chloroplast, peroxisome, mitochondrion, and the cytoplasm. It is unclear how the pathway located in different subcellular compartments respond to stress occurring exclusively in one of those. We attempted to assess the inter-organelle interaction during the photorespiratory pathway. For that purpose, we induced oxidative stress by menadione (MD) in mitochondria and photo-oxidative stress (high light) in chloroplasts. Subsequently, we examined the changes in selected photorespiratory enzymes, known to be located in other subcellular compartments. The presence of MD upregulated the transcript and protein levels of five chosen photorespiratory enzymes in both normal and high light. Peroxisomal glycolate oxidase and catalase activities increased by 50% and 25%, respectively, while chloroplastic glycerate kinase and phosphoglycolate phosphatase increased by ~30%. The effect of MD was maximum in high light, indicating photo-oxidative stress was an influential factor to regulate photorespiration. Oxidative stress created in mitochondria caused a coordinative upregulation of photorespiration in other organelles. We provided evidence that reactive oxygen species are important signals for inter-organelle communication during photorespiration. Thus, MD can be a valuable tool to modulate the redox state in plant cells to study the metabolic consequences across membranes.

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Flexas, Jaume, and Hipólito Medrano. "Energy dissipation in C3 plants under drought." Functional Plant Biology 29, no. 10 (2002): 1209. http://dx.doi.org/10.1071/fp02015.

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A general quantification of the relative contribution of different light energy dissipation processes to total dissipation under different drought conditions is lacking. Here we compare six studies, including enough data for such a general quantification, to build up a general pattern of the relative importance of several energy dissipation mechanisms in response to drought in C3 plants. Such a general pattern apparently emerges independently of specific acclimation to drought, but largely dependent on CO2 availability in the chloroplasts, which may be regulated under drought by adjustments in stomatal and mesophyll conductances. Under irrigation and saturating light, more than 50% of absorbed light is thermally dissipated, while photosynthesis dissipates 20–30% and photorespiration 10–20%. Under mild drought, the contribution of photosynthesis decreases, and that of photorespiration increases in a compensatory manner. During moderate to severe drought, the contribution of both photosynthesis and photorespiration decreases, and thermal dissipation increases up to 70–90% of the total light absorbed. The contribution of other processes, like the Mehler reaction, is shown to be very low under both irrigation and drought. Therefore, in C3 plants subjected to different degrees of drought, more than 90% of the total energy absorbed by leaves is dissipated by the sum of thermal dissipation, photorespiration and photosynthesis.

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Журавлева, В. В., and V. V. Zhuravleva. "Modeling of Processes of Photosynthesis and Photorespiration of C3-Plants." Mathematical Biology and Bioinformatics 10, no. 2 (November 30, 2015): 482–507. http://dx.doi.org/10.17537/2015.10.482.

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The article describes a mathematical model of photosynthesis and photorespiration of C3-plants in the natural environment. The model is sort of physiological one because it takes into account the effect of nitrogen deficiency on the intensity of these processes. A generating solution describing, according to the constructed model, the dynamics of the processes of photosynthesis and photorespiration of C3-plants was found. It is proved that the obtained solution is an asymptotic approximation of the solution of the dynamic system and is sufficient for the calculation of the total daily rate of photosynthesis with satisfactory accuracy (for the problems of forecasting the yield). The results of numerical experiments with daily model of photosynthesis are presented which confirm that the model adequately reflects the daily dynamics of the intensities of the processes of photosynthesis and photorespiration of C3-plants in sowing.

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Fan, Hai, Xu Yun, Ling Li, Xiao Kun Liu, Jie Zhang, and Bao Shan Wang. "Effect of NaCl Stress on the Photosynthetic Attributes of Atriplex centralasiatica." Applied Mechanics and Materials 522-524 (February 2014): 285–89. http://dx.doi.org/10.4028/www.scientific.net/amm.522-524.285.

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Seedlings of Atriplex centralasiatica Iljin were treated with Hoaglands solution containing 0, 200 and 400 mM NaCl respectively, after 2 weeks, Pn, Gs and Ci were measured. Besides, CO2 compensation point, CO2 saturation point, photorespiration rate, plant fresh weight and other physiological parameters were measured. The results showed that under 400 mM NaCl, the decrease of Pn was due to non-stomatal limitation factor. With the increase of NaCl concentrations, CO2 compensation point and CO2 saturation point did not show significant change. The photorespiration rate of the plants treated with 200 mM NaCl showed a little increase. However, under 400 mM NaCl, the increase of photorespiration rate was not that significant. As far as the carboxylation efficiency is concerned, it decreased with NaCl concrntration. At last, the fresh weight showed significant change under 400 mM NaCl treatment, which paralleled with the change of photosynthesis.

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Dellero, Younès, Caroline Mauve, Mathieu Jossier, and Michael Hodges. "The Impact of Photorespiratory Glycolate Oxidase Activity on Arabidopsis thaliana Leaf Soluble Amino Acid Pool Sizes during Acclimation to Low Atmospheric CO2 Concentrations." Metabolites 11, no. 8 (July 30, 2021): 501. http://dx.doi.org/10.3390/metabo11080501.

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Photorespiration is a metabolic process that removes toxic 2-phosphoglycolate produced by the oxygenase activity of ribulose-1,5-bisphosphate carboxylase/oxygenase. It is essential for plant growth under ambient air, and it can play an important role under stress conditions that reduce CO2 entry into the leaf thus enhancing photorespiration. The aim of the study was to determine the impact of photorespiration on Arabidopsis thaliana leaf amino acid metabolism under low atmospheric CO2 concentrations. To achieve this, wild-type plants and photorespiratory glycolate oxidase (gox) mutants were given either short-term (4 h) or long-term (1 to 8 d) low atmospheric CO2 concentration treatments and leaf amino acid levels were measured and analyzed. Low CO2 treatments rapidly decreased net CO2 assimilation rate and triggered a broad reconfiguration of soluble amino acids. The most significant changes involved photorespiratory Gly and Ser, aromatic and branched-chain amino acids as well as Ala, Asp, Asn, Arg, GABA and homoSer. While the Gly/Ser ratio increased in all Arabidopsis lines between air and low CO2 conditions, low CO2 conditions led to a higher increase in both Gly and Ser contents in gox1 and gox2.2 mutants when compared to wild-type and gox2.1 plants. Results are discussed with respect to potential limiting enzymatic steps with a special emphasis on photorespiratory aminotransferase activities and the complexity of photorespiration.

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Maurino, Veronica G. "Using energy-efficient synthetic biochemical pathways to bypass photorespiration." Biochemical Society Transactions 47, no. 6 (November 22, 2019): 1805–13. http://dx.doi.org/10.1042/bst20190322.

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Current crop yields will not be enough to sustain today's diets for a growing global population. As plant photosynthetic efficiency has not reached its theoretical maximum, optimizing photosynthesis is a promising strategy to enhance plant productivity. The low productivity of C3 plants is caused in part by the substantial energetic investments necessary to maintain a high flux through the photorespiratory pathway. Accordingly, lowering the energetic costs of photorespiration to enhance the productivity of C3 crops has been a goal of synthetic plant biology for decades. The use of synthetic bypasses to photorespiration in different plants showed an improvement of photosynthetic performance and growth under laboratory and field conditions, even though in silico predictions suggest that the tested synthetic pathways should confer a minimal or even negative energetic advantage over the wild type photorespiratory pathway. Current strategies increasingly utilize theoretical modeling and new molecular techniques to develop synthetic biochemical pathways that bypass photorespiration, representing a highly promising approach to enhance future plant productivity.

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33

He, P., K. P. Bader, A. Radunz, U. Kahmann, G. H. Ruppel, and G. H. Schmid. "Gas Exchange Characteristics in Leaves of the Euphorbiacea Aleurites montana as Consequence of Growth under 700 ppm CO2 in Air A Study on Photosynthesis and Photorespiration in the Chinese Tung-Oil Tree." Zeitschrift für Naturforschung C 53, no. 3-4 (April 1, 1998): 151–58. http://dx.doi.org/10.1515/znc-1998-3-402.

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Abstract Three months old plants of the Chinese tung-oil tree Aleurites montana (Euphorbiaceae) were cultivated for 4 months in air containing 700 ppm CO2. These plants, which grow substantially better in the CO2-enriched atmosphere, were analyzed by mass spectrometry for photosynthesis and photorespiration together with control plants grown all the time in normal (350 ppm CO2) air. Thereafter part of the plants was subjected for two weeks to 0.3 ppm SO2 in the atmosphere and again analyzed for photosynthesis and photorespiration. Aleurites montana exhibits a strongly CO2-dependent photosynthesis which partially explains the observed stimulatory effect of 700 ppm CO2 on growth of the plant. In control plants grown in normal air, photorespiration measured simultaneously with photosynthesis via the uptake of l80 2 in the light, is much lower than in C3-plants like tobacco (H e et al., 1995, Z. Naturforsch. 50c, 781-788 ). In Aleurites grown in 700 ppm CO2, however, photorespiration is completely absent in contrast to tobacco when grown under 700 ppm CO2. In tobacco, photorespiration is not inhibited to the extent of the in vitro experiments in which plants grown at 350 ppm CO2 are measured under the increased CO2 content of 700 ppm. Gas exchange measurements carried out by mass spectrometry show that the ratio of O2 evolved to CO2 fixed is about 0.5. Apparently, part of the CO2 fixed is channelled into a metabolic path without concomitant O2-evolution. Although the plant has no succulent appearance (its leaves somehow resemble maple leaves) apparently a Crassulacean type metabolism is performed. When Aleurites plants grown all the time in normal air with 350 ppm, are exposed for two weeks to 0.3 ppm SO2 the treatment completely inhibits this CO2-fixing portion which is tentatively attributed to a Crassulacean type of metabolism. This is demonstrated by a normal C3-type ratio O2 evolved /CO2 fixed of 1. When Aleurites plants, grown for 4 months in a CO2-enriched atmosphere of 700 ppm CO2, are subjected for two weeks to 0.3 ppm SO2, the features of control plants show up again. When these plants are tested under 350 ppm CO2 the Crassulacean type CO2-fixation apparently is not inhibited by SO2. Photorespiration, although low, is present in the same activity as in the controls. Seemingly, an increased level of CO2 in air tends to alleviate the impact of the SO2 at least in the Chinese tung-oil tree.

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Tcherkez, Guillaume. "Viewpoint: How large is the carbon isotope fractionation of the photorespiratory enzyme glycine decarboxylase?" Functional Plant Biology 33, no. 10 (2006): 911. http://dx.doi.org/10.1071/fp06098.

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Despite the intense effort developed over the past 10 years to determine the 12C / 13C isotope fractionation associated with photorespiration, much uncertainty remains about the amplitude, and even the sign, of the 12C / 13C isotope fractionation of glycine decarboxylase, the enzyme that produces CO2 during the photorespiratory cycle. In fact, leaf gas-exchange data have repeatedly indicated that CO2 evolved by photorespiration is depleted in 13C compared with the source material, while glycine decarboxylase has mostly favoured 13C in vitro. Here I give theoretical insights on the glycine decarboxylase reaction and show that (i), both photorespiration and glycine decarboxylation must favour the same carbon isotope — the in vitro measurements being probably adulterated by the high sensitivity of the enzyme to assay conditions and the possible reversibility of the reaction in these conditions, and (ii), simplified quantum chemistry considerations as well as comparisons with other pyridoxal 5′-phosphate-dependent decarboxylases indicate that the carbon isotope fractionation favour the 12C isotope by ~20‰, a value that is consistent with the value of the photorespiratory fractionation (f) obtained by gas-exchange experiments.

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Jenkins, Colin L. D. "The CO2 Concentrating Mechanism of C4 Photosynthesis: Bundle Sheath Cell CO2 Concentration and Leakage." Functional Plant Biology 24, no. 4 (1997): 543. http://dx.doi.org/10.1071/pp97027.

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The C4 acid cycle functions in C4 photosynthesis to concentrate CO2 in bundle sheath (BS) cells, thereby minimising oxygenase activity of Rubisco and associated photorespiration. Some key features of this process are reviewed here. During steady-state photosynthesis, the CO2 concentration maintained in BS cells must be a compromise since, at the higher levels required to prevent photorespiration, the potential for CO2 leakage from BS cells would be increased. Despite its central importance in C4 photosynthesis, it has not been possible to precisely determine the BS CO2 concentration. Leakage requires that the C4 cycle rate exceeds the net photosynthesis rate and lowers the efficiency of the overall process. Leakage of CO2 from the BS has been estimated by a number of indirect and, recently, by more direct methods. In a simulation, simple relationships between Rubisco activity, photorespiration, and leakage were calculated at increasing BS CO2 concentrations. From this, and determined values for leakage, the likely concentration of CO2 in BS cells may be 10–20-fold greater than in mesophyll cells. Higher concentrations would have little further effect on oxygenase activity.

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South, Paul F., Amanda P. Cavanagh, Patricia E. Lopez-Calcagno, Christine A. Raines, and Donald R. Ort. "Optimizing photorespiration for improved crop productivity." Journal of Integrative Plant Biology 60, no. 12 (November 5, 2018): 1217–30. http://dx.doi.org/10.1111/jipb.12709.

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37

Sage, Rowan F., Tammy L. Sage, and Ferit Kocacinar. "Photorespiration and the Evolution of C4Photosynthesis." Annual Review of Plant Biology 63, no. 1 (June 2, 2012): 19–47. http://dx.doi.org/10.1146/annurev-arplant-042811-105511.

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38

Kozaki, Akiko, and Go Takeba. "Photorespiration protects C3 plants from photooxidation." Nature 384, no. 6609 (December 1996): 557–60. http://dx.doi.org/10.1038/384557a0.

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39

Raghavendra, Agepati S., Sigrun Reumann, and Hans W. Heldt. "Participation of Mitochondrial Metabolism in Photorespiration." Plant Physiology 116, no. 4 (April 1, 1998): 1333–37. http://dx.doi.org/10.1104/pp.116.4.1333.

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40

Hahn, B. D. "Photosynthesis and photorespiration: Modelling the essentials." Journal of Theoretical Biology 151, no. 1 (July 1991): 123–39. http://dx.doi.org/10.1016/s0022-5193(05)80147-x.

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41

Beardall, J. "Photosynthesis and photorespiration in marine phytoplankton." Aquatic Botany 34, no. 1-3 (July 1989): 105–30. http://dx.doi.org/10.1016/0304-3770(89)90052-1.

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Beer, Sven. "Photosynthesis and photorespiration of marine angiosperms." Aquatic Botany 34, no. 1-3 (July 1989): 153–66. http://dx.doi.org/10.1016/0304-3770(89)90054-5.

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43

Leegood, R. C., P. J. Lea, M. D. Adcock, and R. E. Hausler. "The regulation and control of photorespiration." Journal of Experimental Botany 46, special (September 1, 1995): 1397–414. http://dx.doi.org/10.1093/jxb/46.special_issue.1397.

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44

Ehlers, Ina, Angela Augusti, Tatiana R. Betson, Mats B. Nilsson, John D. Marshall, and Jürgen Schleucher. "Detecting long-term metabolic shifts using isotopomers: CO2-driven suppression of photorespiration in C3 plants over the 20th century." Proceedings of the National Academy of Sciences 112, no. 51 (December 7, 2015): 15585–90. http://dx.doi.org/10.1073/pnas.1504493112.

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Terrestrial vegetation currently absorbs approximately a third of anthropogenic CO2 emissions, mitigating the rise of atmospheric CO2. However, terrestrial net primary production is highly sensitive to atmospheric CO2 levels and associated climatic changes. In C3 plants, which dominate terrestrial vegetation, net photosynthesis depends on the ratio between photorespiration and gross photosynthesis. This metabolic flux ratio depends strongly on CO2 levels, but changes in this ratio over the past CO2 rise have not been analyzed experimentally. Combining CO2 manipulation experiments and deuterium NMR, we first establish that the intramolecular deuterium distribution (deuterium isotopomers) of photosynthetic C3 glucose contains a signal of the photorespiration/photosynthesis ratio. By tracing this isotopomer signal in herbarium samples of natural C3 vascular plant species, crops, and a Sphagnum moss species, we detect a consistent reduction in the photorespiration/photosynthesis ratio in response to the ∼100-ppm CO2 increase between ∼1900 and 2013. No difference was detected in the isotopomer trends between beet sugar samples covering the 20th century and CO2 manipulation experiments, suggesting that photosynthetic metabolism in sugar beet has not acclimated to increasing CO2 over >100 y. This provides observational evidence that the reduction of the photorespiration/photosynthesis ratio was ca. 25%. The Sphagnum results are consistent with the observed positive correlations between peat accumulation rates and photosynthetic rates over the Northern Hemisphere. Our results establish that isotopomers of plant archives contain metabolic information covering centuries. Our data provide direct quantitative information on the “CO2 fertilization” effect over decades, thus addressing a major uncertainty in Earth system models.

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Bai, Xue Liang, Dan Wang, Ning Ning Liu, Li Jing Wei, Ye Rong Zhu, Yan Ling Bai, and Yong Wang. "Construction of Two Vectors for a Bypass of Monocotyledon Plants Photorespiration." Advanced Materials Research 340 (September 2011): 351–56. http://dx.doi.org/10.4028/www.scientific.net/amr.340.351.

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In order to modify the photorespiration of monocotyledonous crops, we aimed to construct vectors that will be used to introduce a bypass to the native photorespiration pathway. Firstly, we cloned the encoding sequences of glyoxylate carboligase (GCL) and tartronic semialdehyde reductase (TSR) fromE. coli, glycolate dehydrogenase (GDH) fromArabidopsis thalianaand chloroplast transit peptide (cTP) from rice. Then we constructed a universal vector pEXP harboring the encoding sequence of cTP for targeting a protein into chloroplast. By insertion of these three encoding sequences into the universal vector pEXP, we obtained the expression cassettes for GCL, TSR and GDH, respectively. Finally, we inserted the cassettes for GCL and TSR in tandem into the binary vector pCAMBIA 1301, and for GDH into another binary vector, pPGN, to obtain our plant expression vectors pCAMBIA 1301-TG and pPGN-GDH, respectively. These two expression vectors possess different selection resistance and can be used to transform monocots together, to introduce the bypass pathway of photorespiration. By this way, the transgenic plants can recycle glycolate, the by-product of photosynthesis in C3plants, within the chloroplast, simultaneously, save energy and avoid the loss of ammonia, which will contribute to improved growth.

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Mebrahtu, Tesfai, James W. Hanover, Desmond R. Layne, and James A. Flore. "Leaf temperature effects on net photosynthesis, dark respiration, and photorespiration of seedlings of black locust families with contrasting growth rates." Canadian Journal of Forest Research 21, no. 11 (November 1, 1991): 1616–21. http://dx.doi.org/10.1139/x91-224.

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Rates of net photosynthesis, dark respiration, and photorespiration of six half-sib families of black locust (Robiniapseudoacacia L.) were measured at leaf temperatures ranging from 10 to 40 °C. Rates of dark respiration increased with increasing leaf temperature in all families and reached as high as 67% of gross photosynthesis at 40 °C in one family. Dark respiration of foliage accounted for 12.5 to 59% of the reduction in net photosynthesis at temperatures higher than those optimum for net photosynthesis. Rates of photorespiration peaked at 10 to 20 °C, exhibiting the same pattern as net photosynthesis, and did not contribute to the decline in net photosynthesis at high temperatures. The families with high rates of net photosynthesis also had high rates of photorespiration. Rates of dark respiration were significantly different among the families, and the slow-growing families had the highest rates of dark respiration. A significant interaction between half-sib families and leaf temperatures was noted for dark respiration. The data indicated the possibility of improving the growth of black locust by selection and breeding for large leaf area, high rates of net photosynthesis and low rates of dark respiration.

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Ziegler, Christine, and Aloysius Wild. "The Effect of Bialaphos on Ammonium-Assimilation and Photosynthesis II. Effect on Photosynthesis and Photorespiration." Zeitschrift für Naturforschung C 44, no. 1-2 (February 1, 1989): 103–8. http://dx.doi.org/10.1515/znc-1989-1-218.

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Abstract The application of bialaphos (phosphinothricyl-alanyl-alanine) effects a quick photosynthesis inhibition under atmospheric conditions (400 ppm CO2, 21% O2). However, under conditions (1000 ppm CO2, 2% O2) under which photorespiration cannot occur there is no photosynthesis inhibition. In the previous investigation it could be shown that bialaphos splits in plants into phosphinothricin and alanine. The inhibition of glutamine synthetase through freed phosphinothricin results in an NH4+-accumulation and a decrease in glutamine. With the addition of glutamine, photosynthesis inhibition by bialaphos can be reduced. An NH4+-accumulation takes place under atmospheric conditions as well as under non-photorespiratory conditions; though in the latter case, in less amounts. After adding glutamine and other amino acids the NH4+-accumulation increases especially. This indicates that NH4+-accumulation cannot be the primary cause for photosynthesis inhibition by bialaphos. The investigations indicate that for the effectiveness of either bialaphos or phosphinothricin, a process in connexion with photorespiration plays a considerable role. The glyoxylate transamination in photorespiration could be inhibited, which results probably on a glyoxylate accumulation. Corresponding investigations showed inhibition of photosynthesis as well as a direct inhibition of RubP-carboxylase with glyoxylate.

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Tao, Yumin, Li-Wei Chiu, Jacob W. Hoyle, Rebecca A. Dewhirst, Christian Richey, Karli Rasmussen, Jessica Du, et al. "Enhanced Photosynthetic Efficiency for Increased Carbon Assimilation and Woody Biomass Production in Engineered Hybrid Poplar." Forests 14, no. 4 (April 18, 2023): 827. http://dx.doi.org/10.3390/f14040827.

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Increasing CO2 levels in the atmosphere and the resulting negative impacts of climate change have compelled global efforts to achieve carbon neutrality or negativity. Most such efforts focus on carbon sequestration through chemical or physical approaches. Harnessing the power of synthetic biology to enhance the natural ability of carbon sequestration in plants, especially non-annuals, provides a biological approach to further reduce CO2 levels in the air. Here, we selected a photorespiration bypass pathway and tested its effectiveness on photosynthetic enhancement in a hybrid poplar, INRA717-IB4. The design includes an RNAi strategy to reduce the transportation of the photorespiration byproduct, glycolate, out of chloroplast and a shunt pathway to metabolize the retained glycolate back to CO2 for fixation through the Calvin-Benson cycle. Molecular and physiological data collected from two separate growth experiments indicate that transgenic plants expressing genes in the photorespiration bypass pathway have increased photosynthetic efficiency, leading to faster plant growth and elevated biomass production. One lead transgenic event accumulated 35%–53% more above-ground dry biomass over four months of growth in a controlled environment. Our results provide a proof of concept for engineering trees to help combat climate change.

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Meloni, Diego Ariel, and Carlos Alberto Martínez. "PHYSIOLOGICAL RESPONSES OF Eucalyptus camaldulensis (Dehnh.) TO SIMULATED GLYPHOSATE DRIFT." BIOFIX Scientific Journal 6, no. 1 (January 4, 2021): 46. http://dx.doi.org/10.5380/biofix.v6i1.77236.

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Weed control with glyphosate produces damages in plantations of Eucalyptus camaldulensis, although the involved physiological mechanisms have not been completely elucidated. This work aimed at assessing the physiological responses of E. camaldulensis to simulated glyphosate drift. Greenhouse trials were performed with four-month-old E. camaldulensis clone117 seedlings. The herbicide drift was simulated applying doses of 0; 43,2; 86,4; 172,8 and 345,6 g a.e. ha−1 glyphosate. Twenty-three days after the application, we measured gas exchange and chlorophyll a fluorescence. We also quantified Rubisco activity and indicator variables of oxidative stress. Glyphosate decreased carbon photosynthetic assimilation, increased non-photochemical quenching, induced stomatal closure, and increased photoinhibition. It also decreased Rubisco activity and increased photorespiration. The herbicide produced oxidative stress, and increased the activities in the enzymes catalase, ascorbate peroxidase, and superoxide dismutase, involved in the detoxification of reactive oxygen species. We concluded that glyphosate´s deleterious effects on the assimilation of CO2 in E. camaldulensis are due to stomatal and non-stomatal effects. The decrease in Rubisco activity, the increase in photorespiration, and photoinhibition stand out among non-stomatal effects. The increase in the activity of the antioxidant system is insufficient to compensate for the production of H2O2 in photorespiration, which damages the photosynthetic apparatus.

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Santhanagopalan, Indu, Rachel Wong, Tanya Mathur, and Howard Griffiths. "Orchestral manoeuvres in the light: crosstalk needed for regulation of the Chlamydomonas carbon concentration mechanism." Journal of Experimental Botany 72, no. 13 (April 20, 2021): 4604–24. http://dx.doi.org/10.1093/jxb/erab169.

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Abstract The inducible carbon concentration mechanism (CCM) in Chlamydomonas reinhardtii has been well defined from a molecular and ultrastructural perspective. Inorganic carbon transport proteins, and strategically located carbonic anhydrases deliver CO2 within the chloroplast pyrenoid matrix where Rubisco is packaged. However, there is little understanding of the fundamental signalling and sensing processes leading to CCM induction. While external CO2 limitation has been believed to be the primary cue, the coupling between energetic supply and inorganic carbon demand through regulatory feedback from light harvesting and photorespiration signals could provide the original CCM trigger. Key questions regarding the integration of these processes are addressed in this review. We consider how the chloroplast functions as a crucible for photosynthesis, importing and integrating nuclear-encoded components from the cytoplasm, and sending retrograde signals to the nucleus to regulate CCM induction. We hypothesize that induction of the CCM is associated with retrograde signals associated with photorespiration and/or light stress. We have also examined the significance of common evolutionary pressures for origins of two co-regulated processes, namely the CCM and photorespiration, in addition to identifying genes of interest involved in transcription, protein folding, and regulatory processes which are needed to fully understand the processes leading to CCM induction.

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Journal articles on the topic 'Photorespiration'

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