Plant immune system: Mechanisms and resilience

Plants are continuously challenged by abiotic and biotic factors. Threat due to diseases and pests causes yield losses, and hence resistance buildup is necessary for plants to survive and grow during their life cycle. Plants have developed an immune system (cell surface and intracellular) to fight against phytopathogens. It is now well understood that the mechanistic cues of cell-surface and intracellular immune systems work in liaison and function in a cooperative mode. The plasma membrane-resident receptor-like kinases and intracellular nucleotide-binding domain leucine-rich repeat (NLRs) receptors participate in the pattern- and effector-triggered immunity. The receptor-mediated activation of defense gene expression and synthesis of phytohormone salicylic acid (SA) result in transcriptional reprogramming to elicit the immune responses. In this chapter, we present an account of the plant immune system and the molecular mechanisms, the integral components, and the involvement of SA. Current research trends in the area of plant immunity can potentially offer clues on plant-pathogen interactions and the means to develop disease resistance in crop plants.