大豆叶片旱促衰老及其与膜脂过氧化的关系

The Acceleration of Senescence of Soybean Leaves Induced by Drought and Its Relation to Membrane Lipid Peroxidation

干旱导致大豆叶片叶绿素和可溶性蛋白质含量下降,膜透性增加。不同叶位比较以生理老叶受影响较大。分析表明,干旱条件下叶片膜脂过氧化作用加强,H_2O_2累积,过氧化物酶活性提高;而活性氧清除系统的超氧化物歧化酶和过氧化氢酶活性以及抗坏血酸和还原型谷胱甘肽水平降低。干旱6天不同叶位叶间以生理老叶具较高的丙二醛和H_2O_2含量和较低的保护酶活性、抗氧化物质水平。

Soybean variety Ludou No. 4 was subjected to drought by withholding water inpots under natural conditions for 6 days, the relationship between drought inducedsenescence and membrane lipid peroxidation was studied. The results indicated that insoybean ieaves drought stress produced a markable decrease in both chlorophyll andsoluble protein, a phenomenon characteristic of senescing tissues. Activity ofperoxidase (POX), membrane permeability and contents of both H_2O_2 andmalondialdehyde, an index of membrane lipid peroxidation, increased in response tostress, but activities of catalase (CAT) and superoxide dismutase (SOD) and contentsof ascorbic acid (ASA) and reduced glutathione (GSH) decreased. All of thesechanges were much more pronounced in lower, older leaves than in upper, youngerones and physiological old leaves senesced invariably during an imposed drought stresswhile control leaves with comparable age and stressed younger leaves remained green.It is reasonable to suggest that drought induced membrane lipid peroxidation mayplay an important role in drought accelerated senescence of soybean leaves.