Plant hormone crosstalks under biotic stresses

Abstract

Plants have developed defense signaling systems to protect themselves from invading pathogens. Plant hormones such as salicylic acid, jasmonates, and ethylene act as signals to trigger and mediate a diverse array of defense responses. Other hormones such as abscisic acid, auxin, gibberellic acids, cytokinins, and brassinosteroids, which were previously implicated in developmental and abiotic stress responses, also play important roles in defense signaling against pathogens. These hormone signaling pathways interconnect in an antagonistic or synergistic manner, providing plants with a vast regulatory potential to adapt rapidly to their biotic environment and to use their limited resources for growth and survival in a cost-efficient manner. On the other hand, pathogens have developed strategies to manipulate the signaling network and increase their virulence. This chapter reviews recent progress in research on the roles of hormone signaling pathways and their interactions in plant defense, mainly focusing on the salicylic acid signaling pathway and its interactions with other pathways. In addition to studies on Arabidopsis and other dicots, we also discuss some of the studies on rice, a monocot model plant, because such studies have provided some additional insights into the effects of signaling crosstalks on resistance to abiotic and biotic stresses. We also discuss some of the biotechnological and pharmaceutical strategies to manipulate defense hormone signaling to improve the disease tolerance of crops.