Effect of intermediates on ascorbic acid and oxalate biosynthesis of rice and in relation to its stress resistance.
Rice (Oryza sativa L.) roots were fed with L-ascorbic acid (AsA) and its putative precursors to observe AsA and oxalate concentrations and the resistance of rice to chilling, water stress, and Al toxicity. AsA concentration was significantly enhanced in both shoots and roots of rice seedlings by feeding with D-glucose or L-galactono-gamma-lactone. AsA or L-galactono-gamma-lactone treatment increased accumulation of oxalate mainly in soluble form, while these treatments decreased electrolyte leakage from root cells, H2O2 and lipid peroxidation level in rice seedlings subjected to chilling, water stress, and Al toxicity. They also alleviated the inhibition on root growth by Al. These results indicated that AsA and its immediate precursor protected plants against the oxidative damages induced by various stresses. However, 0.5 mM AsA and 10 mM L-galactono-gamma-lactone treatment had no significant effect on superoxide dismutase and catalase activity and ascorbate-peroxidase activities. Enhanced Al resistance caused by AsA and L-galactono-gamma-lactone may possibly be resulted from increased level of oxalate, which acts as metal chelator. Thus it is proposed that manipulation of AsA and oxalate biosynthesis through enhancement of L-galactono-gamma-lactone level in plants could be a strategy for improving abiotic stress tolerance.
Guo
Zhenfei
Z
Biotechnology Laboratory for Turfgrass and Forages, College of Life Science, South China Agricultural University, Guangzhou 510642, China. zhfguo@scau.edu.cn
Tan
Huoquan
H
Zhu
Zhihui
Z
Lu
Shaoyun
S
Zhou
Biyan
B
D000535:Aluminum / Q000633:toxicity; D001205:Ascorbic Acid / Q000096:biosynthesis* / Q000378:metabolism; D002374:Catalase / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D015227:Lipid Peroxidation; D012275:Oryza / Q000201:enzymology / Q000378:metabolism* / Q000502:physiology; D010070:Oxalates / Q000378:metabolism*; D018384:Oxidative Stress; D013482:Superoxide Dismutase / Q000378:metabolism; D014867:Water
D010070:Oxalates; D014867:Water; D006861:Hydrogen Peroxide; D000535:Aluminum; D002374:Catalase; D013482:Superoxide Dismutase; D001205:Ascorbic Acid