Jasmonates in Plant Defense Responses

Abstract

Plants constantly interact with a wide range of life-threatening organisms including herbivorous arthropods and pathogenic microbes. The plant fatty acid–derived jasmonates produced in response to biotic stresses are essential to survival. These oxylipins constitute part of the plant’s sophisticated strategy to defend itself. Upon biotic attack, the increased accumulation of these metabolites diverts energy away from growth needs and channels it toward defense. The complex interplay between jasmonates and invader-specific elicitors provides the plant with gene expression regulatory potential to launch effective responses against the invaders. Such responses can be either direct, by producing molecules that are toxic to the invading organisms, or indirect, by attracting the natural enemies of such invaders. Jasmonates are also critical components in mediating the plant stress-induced systemic signal(s) to activate defense-related genes. The availability of jasmonate mutants has been crucial in identifying the roles these metabolites play in plant stress responses. In this chapter, we present an overview of jasmonate function in insect and pathogen defense, the cross talk between jasmonates and other phytohormones in fine-tuning such defenses, and the possible role these oxylipins play in mediating mechanoresponses.