Abstract:During germination of peanut seeds, exogenous abscisic acid(ABA) affected the endopeptidase and degradation of storage proteins. When dry peanut seeds were germinated directlywith 100μmol/L ABA, the endopeptidase activity and arachin degradation were severely inhibitedand the endopeptidase isoenzyme was not displayed on polyacryamide gel after electrophoresis.After peanut seeds were genminated 2 days in water, exogenous ABA (100μmol/L) only reducedendopeptidase activity, but did not affect endopeptidase isoenzyme, storage proteins andarachin degradation. The experiments in which peanut seeds were germinated in the presenceof ABA and Cycloheximide (protein synthesis inhibitor) and 5-fluorouracil (RNA synthesisinhibitor) showed that the role of ABA in inhibiting endopeptidase activity and arachindegradation was not dependent on the synthesis of nucleic acid and protein. The nucleicacid synthesis inhibitors (Actinomycin D, Cordycepin, 5-Fluorouracil) and proteinsynthesis inhibitor (Cycloheximide) depressed endopeptidase activity, but did not affect theendopeptidase isoenzyme and arachin degradation. The results showed that theendopeptidase which degradeted arachin in cotyledons during peanut seed germination wasnot de novo synthesized. We propose that the endopeptidase was synthesized during seeddevelopment and played an important role in degradation of arachins during germination.The regulation of endopeptidase activity and the model of storage protein degradation duringpeanut seed germination were discussed.
