Senescence of rice leaves .35. Promotive effects of jasmonates

Promotion of the senescence of detached rice leaves by jasmonates was investigated. The senescence of detached rice leaves was promoted by linolenic acid, the precursor of the biosynthesis of jasmonic acid, and retarded by inhibitors of lipoxygenase, the first enzyme in the biosynthetic pathway of jasmonic acid. Linolenic acid-promoted senescence was found to be inhibited by lipoxygenase inhibitors. Among the four major lipoxygenase path way metabolites studied, jasmonic acid and methyl jasmonate were effective in promoting the senescence of detached rice leaves while traumatic acid and trans-2-hexenal had no or only marginal effect on it. The results support a role for endogenous jasmonates in regulating the senescence of detached rice leaves.