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evolution
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in plants, MDHAR belongs to a multigene family
evolution
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in plants, MDHAR belongs to a multigene family
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malfunction
insertional inactivation of the MDAR2 (At3g09940) gene and the dehydroascorbate reductase 5 (DHAR5, At1g19570) gene shows that they are crucial for maintaining the interaction between Piriformosporaindica and Arabidopsis in a mutualistic state, and under drought stress in particular
malfunction
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transgenic lines overexpressing MDHAR show a decrease in ascorbate levels in leaves, whereas lines where MDHAR is silenced show an increase in these levels in both fruits and leaves
malfunction
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transgenic lines overexpressing MDHAR show a decrease in ascorbate levels in leaves, whereas lines where MDHAR is silenced show an increase in these levels in both fruits and leaves
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metabolism
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the enzyme is involved in the ascorbate recycling pathway, overview
metabolism
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the enzyme is involved in the ascorbate recycling pathway, overview
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physiological function
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MDAR-OX plants do not show better root growth than wild type plants after exposure to 0.4 mM aluminium for 2 weeks
physiological function
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MDARis a key enzyme in the ascorbate-glutathione cycle, MDAR is crucial for ascorbate regeneration and essential for maintaining the reduced pool of ascorbate
physiological function
overexpression of chloroplastic monodehydroascorbate reductase enhances tolerance to temperature and methyl viologen-mediated oxidative stresses. Overexpression of chloroplastic MDAR plays an important role in alleviating photoinhibition of photosystem I and II and enhancing the tolerance to various abiotic stresses by elevating ascorbate level
physiological function
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the enzyme is involved in maintaining the reactive oxygen species scavenging capability of plant cells, as regeneration of ascorbate from its primary oxidation product monodehydroascorbate, an essential process and obviously indispensable. With its ability to directly regenerate ascorbate, MDHAR probably plays an important role in the plant antioxidant system by maintaining the pool of ascorbate. Chloroplastic MDHAR plays an important role in alleviating photoinhibition of PSII by elevating ascorbate (AsA) level under salt- and PEG-induced osmotic stress
physiological function
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the enzyme negatively regulates ascorbate levels in Solanum lycopersicum, isozyme MDHAR3 activity has a negative impact on ascorbate levels in both leaves and fruits
physiological function
in transgenic lines with reduced MDHAR activity, large decreases in fruit MDHAR activity are observed. This correlates with slight losses in fruit firmness and fruit ascorbate, independently of the genetic background. Fruit colour after chilling is also positively correlated with the redox state of the ascorbate pool and fruit firmness. Red fruit of transgenic lines show increased glutathione levels
physiological function
knockdown of MDHAR4 through virus-induced gene silencing enhances the wheat resistance to Puccinia striiformis f. sp. tritici by inhibiting sporulation in the compatible interaction. Gene silencing results in an increased proportion of necrotic area at the infection sites and suppresses Puccinia striiformis f. sp. tritici hypha elongation
physiological function
MDHAR knockdown results in improved wheat resistance to wheat stripe rust, caused by Puccinia striiformis f. sp. tritici, at the seedling stage. Knockdown has no influence on 1136-P3 and PN-2013 microRNA expression. MDHAR knockdown results in a much greater H2O2 accumulation and lower ascorbate peroxidase and catalase activities together with higher expression in several plant resistance genes
physiological function
transgenic lines overexpressing MDHAR show a decrease in ascorbate levels in leaves, lines where MDHAR is silenced show an increase in these levels in both fruits and leaves. The intensity of these differences is light dependent
physiological function
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yeast cells expressing Oryza sativa MDHAR display enhanced tolerance to hydrogen peroxide by maintaining redox homoeostasis, proteostasis, and the ascorbate-like pool following the accumulation of antioxidant enzymes and molecules, metabolic enzymes, and molecular chaperones and their cofactors. The survival of MDHAR-expressing cells is greater than that of wild-type when exposed to high concentrations of ethanol. High MDHAR expression also improves the fermentative capacity of the yeast during glucose-based batch fermentation at 30°C. The alcohol yield of MDHAR-expressing transgenic yeast during fermentation is approximately 25% higher than that of wild-type yeast
physiological function
in cv. Moneymaker, RNAi lines for monodehydroascorbate reductase do not show significant yield decrease compared to control lines when plants are grown under carbon stress generated by mature leaf removal. A decrease in monodehydroascorbate reductase activity in fruit of cherry tomato has no effect on yield compared to a reduction in whole-plant monodehydroascorbate reductase activity
physiological function
monodehydroascorbate reductase acts as a key stress regulator by modulating the activity of antioxidant enzymes to strengthen the ROS scavenging ability and maintains ROS homeostasis. Arabidopsis thaliana transgenic plants expressing Mdar do not show any significant differences in the growth pattern and plant morphology. Under 100 mM NaCl stress, transgenic plants show better growth as compared to the wild-type plants
physiological function
OPR3 is a bifunctional enzyme with NADPH-dependent alpha,beta-ketoalkene double-bond reductase and monodehydroascorbate reductase activities. OPR3 mutants show a slightly less-reduced ascorbate pool in leaves in line with the MDHAR activity of OPR3 in vitro. OPR3 catalyzes the reduction of a wide spectrum of electrophilic species that share a reactivity toward the glutathione and ascorbate. 12-oxophytodienoic acid reacts with ascorbate to form an ascorbate-12-oxophytodienoic acid adduct, but in addition OPR3 has the ability to regenerate ascorbate from monodehydroascorbate
physiological function
upon overexpression of MDAR1, the cells survive under very high-intensity light stress (VHL), while the survival of control cells decreases for 1.5 h under VHL stress. VHL increases lipid peroxidation of controls but does not alter lipid peroxidation in MDAR1 overexpression lines. Overexpression of MDAR1 leads to an increase in viability and the ascorbate:dehydroascorbate ratio. An R1 knockdown line exhibits a low MDAR transcript abundance and enzyme activity and the survival decreases under HL conditions. HL illumination decreases MDAR1 transcript abundance, enzyme activity and ascorbate:dehydroascorbate ratio of MDAR1-downregulation lines
physiological function
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the enzyme negatively regulates ascorbate levels in Solanum lycopersicum, isozyme MDHAR3 activity has a negative impact on ascorbate levels in both leaves and fruits
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physiological function
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the enzyme is involved in maintaining the reactive oxygen species scavenging capability of plant cells, as regeneration of ascorbate from its primary oxidation product monodehydroascorbate, an essential process and obviously indispensable. With its ability to directly regenerate ascorbate, MDHAR probably plays an important role in the plant antioxidant system by maintaining the pool of ascorbate. Chloroplastic MDHAR plays an important role in alleviating photoinhibition of PSII by elevating ascorbate (AsA) level under salt- and PEG-induced osmotic stress
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additional information
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overexpression of MDHAR enhanced tolerance to osmotic stress
additional information
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overexpression of the enzyme in rice plants increases the plant's salt tolerance. The leaf segments from transgenic lines remain green while the leaf segments from the wild-type plants show severe bleaching at 150 mM NaCl. The salinity tolerance of these transgenic rice lines is enhanced at germination and seedling stages
additional information
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overexpression of MDHAR enhanced tolerance to osmotic stress
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