轻度水分胁迫的小麦幼苗中与呼吸有关的几种酶活性变化

轻度水分胁迫使小麦幼苗叶片呼吸升高时,叶中琥珀酸去氢酶和细胞色素氧化酶活性均明显升高;而同样胁迫使根呼吸下降时,根中这两种酶活性均明显下降。叶和根中ATP酶分解活性在胁迫下都明显升高。轻度水分胁迫使叶片过氧化氢酶活性升高。叶中有明显的乙醇酸氧化酶活性,抗旱品种的酶活性较高,胁迫使此酶活性降低。

Changes in Activities of Some Enzymes Related to Respiration in Slightly Water-Stressed Wheat Seedlings

On the basis of previous work, the cffectof water stress on enzyme activity related to therespiration have been further studied with theaim of understanding the cause of changes inrespiration metabolism of wheat seedlings understress. The activities of succinic dehydrogenaseand cytochrome oxidase were measured by themethod of Machler et. al. (1956). The determi-nation of ATP ase activity was performed as des-cribed by Tuppy et al. (1976). The activity ofcatalase was assayed with oxidimetry and ex-pressed as the rate of H_2O_2 decomposion. Theactivity of glycolic acid oxidase was estimatedwith oxygen electrode method according to Cla-gett et al. (1949), by determining oxygen con-sumption after the addition of glycolic acid. Water stress affected respiratory rate andchanged markedly the activities of enzymesrelated to the respiration in wheat seedlings.The activities of succinic dehydrogenase and cy-tochrome oxidase increased with the increase ofrespiration in young leaves unde? a-1.5MPa osmo-tic stress by PEG for 5 hours. However, theactivities of the above enzymes decreased withthe decrease of respiration in roots under thesame stress. The hydrolyzing activity of ATP-ase in mitochondria and supernatant from leavesand roots increased markedly when the plants wereunder water stress. The activity of catalase inleaves was high and increased further underslight water stress. There was evident glycolicacid. oxidase activity in wheat leaves, and theactivity in drought-resistant varieties was higherthan. that in drought-sensitive varieties. Underwater stress the activity of this enzyme decreased.