脱落酸和抑制剂对萌发花生子叶肽链内切酶和花生球蛋白降解的影响

EFFECTS OF ABSCISIC ACID AND INHIBITORS ON ENDOPEPTIDASE AND ARACHIN DEGRADATION DURING PEANUT (ARACHIS HYPOGAEA L.) SEED GERMINATION

摘要:

脱落酸（Ａｂｓｃｉｓｉｃａｃｉｄ，ＡＢＡ）抑制花生种子萌发的作用与核酸和蛋白质合成抑制剂的作用不同．ＡＢＡ（１００μｍｏｌ／Ｌ）在萌发零时施用，明显抑制肽链内切酶活性和同工酶表现以及花生球蛋白降解，萌发４８ｈ施用ＡＢＡ（１００μｍｏｌ／Ｌ）只降低肽链内切酶活性．ＡＢＡ的抑制作用不依赖于核酸和蛋白质合成．核酸合成抑制剂（３＇－脱氧腺苷，放线菌素Ｄ，５－氟尿嘧啶）和蛋白质合成抑制剂（亚胺环己酮）只能部分降低肽链内切酶活性，对肽链内切酶同工酶表现和花生球蛋白降解无明显影响．实验结果表明花生子叶肽链内酶不是在种子萌发过程中重新（ｄｅｎｏｖｏ）合成，文中讨论了肽链内切酶活性调节和花生贮藏蛋白降解的起始模式．

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.