Networking by small-molecule hormones in plant immunity

Abstract: Plants live in complex environments in which they intimately interact with a broadrange of microbial pathogens and insect herbivores with different lifestyles and infection orfeeding strategies. The evolutionary arms race between plants and their attackers provided plantswith a sophisticated defense system that, like the animal innate immune system, recognizes theattacker and responds by activating specific defenses that are specifically directed against theinvader. Recent advances in plant immunity research provided exciting new insights into theunderlying defense signaling network. Diverse small-molecule hormones play pivotal roles in theregulation of this network. Their signaling pathways cross-communicate in an antagonistic orsynergistic manner, providing the plant with a powerful capacity to finely tailor its immuneresponse to the attacker encountered. Pathogens and insects, on the other hand, can manipulatethe plant’s defense signaling network for their own benefit by affecting phytohormonehomeostasis to antagonize the host immune response.