Effect of Inhibitors of Polyamine Biosynthesis on Gibberellin-Induced Internode Growth in Light-Grown Dwarf Peas

概要

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When gibberellic acid (GA_3) is sprayed on 9-day-old light-grown dwarf Progress pea (Pisum sativum) seedlings, arginine decarboxylase (ADC; EC 4.1.1.9) activity increases within 3 h and peaks at about 9 h after GA_3 application. This is followed by a second lower peak at about 30 h; both peaks were higher than the corresponding peaks in the controls. In contrast, no appreciable effect of GA_3 on internode length was observed until about 12 h, after which time a dramatic increase in growth rate occurred and persisted for about 12 h. Specific (DL-α-difluoromethylarginine) and non-specific (D-arginine and L-canavanine) inhibitors of ADC strongly inhibited ADC activity and to a lesser extent internode growth. The inhibition was reversed only slightly by the addition of polyamines. Actinomycin D and cycloheximide inhibited the rise in ADC activity induced by GA_3 The half-life of the enzyme was increased by GA_3 treatment. The results suggest that part of the GA_3-induced increase in internode growth may result from enhanced polyamine biosynthesis through the ADC pathway. Furthermore, the GA_3 induced increase in ADC activity probably requires de novo synthesis of both RNA and protein.
日本植物生理学会の論文