Chapter 23 Salicylic acid: signal perception and transduction

Abstract

Salicylates, including salicylic acid (SA), methyl salicylate, saligenin and their respective glucosides, are natural products of plant metabolism that have long been known to possess therapeutic properties. SA has been also demonstrated to affect gene expression by altering the activity of transcription factors, Furthermore, phenols like SA are capable of directly binding to proteins and thereby altering their ability to transduce cellular signals. SA has been shown to play an important role in signaling defense responses in several plant species. Biochemical, molecular and genetic techniques have recently been used to address the pathways associated with SA metabolism, signal perception and transmission. This chapter will focus primarily on the progress made in deciphering the role SA plays in activating plant defense reponses. In particular, recent advances made in identifying SA's targets, and mode(s) of action, as well as the mechanism(s) through which the SA signal is amplified and exerted at the level of gene expression is presented. Recent progress has uncovered the complex nature of these responses in plants, as well as the presence of cross talk between multiple signaling pathways. SA has emerged as an important player in the ability of several dicotyledonous species to curtail the growth and spread of pathogens; additionally, SA influences several other plant processes.