Wound-induced RNase in senescing bean pod tissue : post-transcriptional regulation of RNase

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RNase (E. C. 2. 7. 7. 16) in endocarp of Phaseolus vulgaris L. var. Kentucky Wonder is induced by cutting; it increases in activity (phase I), peaks in 6 hr and then declines (phase II). Induction depends on synthesis of RNA and protein. RNase degradation in presence of cycloheximide has a half-time of about 3 hr during phase I and II. Addition of actinomycin D (ACTD) between 30 min and 2 hr after cutting enhances RNase synthesis (superinduction) for over 24 hr, indicating that RNase mRNA is long-lived. Superinduction depends on protein synthesis and is not due to inhibition of RNase degradation. Since RNase mRNA is long-lived and the rate of RNase degradation is the same in both phase I and II it may be concluded that control of RNase is at translation. We suggest that cutting of tissue induces transcription of 2 mRNAs, one for RNase and the other for a repressor that prevents translation of RNase mRNA. Repressor accumulation causes inhibition of RNase synthesis so that net degradation of RNase prevails. ACTD superinduction may be attributed to inhibition of formation of the repressor, which would allow continued translation of the s table RNase messenger.
日本植物生理学会の論文