AIRBORNE SIGNALING BY METHYL SALICYLATE IN PLANT PATHOGEN RESISTANCE

Methyl salicylate, a volatile liquid, also known as oil of wintergreen , is made by a number of plants(1-9). Here we show that methyl salicyl ate is a major volatile compound produced by tobacco plants inoculated with tobacco mosaic virus. Methyl salicylate is synthesized from sali cylic acid, a mon-volatile chemical signal required for the establishm ent of acquired resistance(10) and local and systemic induction of ant imicrobial pathogenesis-related proteins(11). Methyl salicylate acts b y being converted back to salicyclic acid. We conclude that methyl sal icylate may function as an airborne signal which acitvates disease res istance and the expression of defence-related genes in neighbouring pl ants and in the healthy tissues of the infected plant.