Regulation of Pisatin Biosynthesis in Pea Leaves by Elicitor and Suppressor Produced by Mycosphaerella pinodes

Abstract

Regulation of pisatin biosynthesis in naked mesophyll tissue of pea leaves by suppressor (F5) and elicitor isolated from Mycosphaerella pinodes was studied using a radioactive precursor of pisatin synthesis, ¹⁴C-phenylalanine. Incorporation of radioactivity became detectable 4.5-6 hr after elicitor treatment and increased thereafter. Concomitant presence of F5 inhibited the pisatin inducing activity of the elicitor completely. Treatment of pea leaves with F5 after elicitor-activation caused a reduction of pisatin synthesis and an increased accumulation of cinnamic acid, an intermediate of pisatin synthesis. F5 was found to inhibit in vitro the activity of phenylalanine ammonia-lyase and cinnamate 4-hydroxylase. The suppressing ability of F5 on pisatin synthesis seemed to be reversible.