Ascorbate and Homoglutathione Metabolism in Common Bean Nodules under Stress Conditions and during Natural Senescence

摘要: Ascorbate and glutathione are major antioxidants redox buffers in plant cells but also play key functions growth, development, stress responses. We have studied the regulation of ascorbate homoglutathione biosynthesis common bean (Phaseolus vulgaris) nodules under conditions during aging. The expression five genes biosynthetic pathway was analyzed nodules, evidence found that l-galactono-1,4-lactone dehydrogenase, last committed step pathway, is posttranscriptionally regulated. Also, conditions, γ-glutamylcysteine synthetase translationally regulated, (mRNA activity) (content state) were not affected. Most interestingly, exposed to jasmonic acid, dehydroascorbate reductase activity posttranslationally suppressed, oxidase showed strong transcriptional up-regulation, content increased moderately. These changes due a direct effect acid on enzyme activities might be part signaling response stress. determined ascorbate, homoglutathione, ascorbate-glutathione two senescing stages undergoing oxidative When all parameters expressed nodule fresh weight basis, we first stage decreased by 60% antioxidant remained fairly constant, whereas second their states, associated significantly decreased. coexistence same plants at different senescence stages, with concentrations indicates life span controlled endogenous factors points as one players.