Plant-microbe interaction: Gene-to-metabolite network

Abstract

Plants and microbes interact with one another in a beneficial/neutral or unfavorable manner. These plant-microbe associations affect plant physiological processes, where plants maintain balances between plant fitness costs and defense responses. For the establishment of effective plant-microbe relationship/invasion, a microbe has to first pass through the plant preformed barriers and defense machineries. To limit the microbial entry and pathogen propagation or kill pathogens, plant cells trigger immune response. Plant immune signaling consists of two defense cascades: microbe/pathogen-associated molecular pattern (MAMP/PAMP)-triggered immunity (MTI/PTI) and effector-triggered immunity (ETI). Both MTI/PTI and ETI networks comprise of structurally and functionally diverse genes, proteins, and/or small molecules that are tightly regulated via feedback loop(s). The signaling cascade involves number of events such as ion fluxes, mitogen-activated protein kinases (MAPKs), biosynthesis/regulation of plant hormones, calcium protein kinase, lipids, proteins, transcriptional programming, stomatal closure, callose deposition, lignification, along with calcium burst and generation of reactive oxygen species. The present chapter addresses plant and microbe metabolites with pivotal roles in plant-microbe interactions, plant perception systems for pathogen recognition, and how these defense molecules interact to activate defense networks in plants.