Chapter 11 - Primary Plant Metabolism During Plant–Pathogen Interactions and Its Role in Defense

Abstract

Like all other living systems, plants also face a wide array of biotic and abiotic stresses from the highly versatile nature. In the absence of an ambulatory immune system as in animals, plants adopt a sophisticated dual-edge mechanism to manage stress. Biotic stress in plants ensues as a result of structural and/or functional damages caused by insects, weeds, and major pathogenic microorganisms. The first line of plant defense through the pathogen-associated molecular pattern (PAMP/MAMP) recognition system, which recognizes the pathogen, and this is followed by a series of signal changes finally imparting a defense strategy. For many years the role of primary metabolites in plants' adaptive defense response was largely unknown. However, now, it is well known that the primary metabolite variations in the host plant, which include a reduction in the essential photosynthesis machinery, lead to the activation of various defense genes. Moreover, the changes associated with carbohydrate and amino acid metabolism demonstrated significant role in activating host's defense mechanism. Primary level of changes associated with pathogen recognition by the plants include photosynthesis-associated changes, pathogenesis-related protein synthesis, reorganization of the cytoskeleton, production of reactive oxygen species, and activation of programmed cell death. These primary metabolic changes eventually lead to a massive energy redistribution in the host plant, resulting in an enhanced mode of preparedness against pathogen. This review focuses on the primary in vivo changes allied with a plant–pathogen encounter, specifically leading to the activation of systemic resistance.