From cellular cleanup to defense: the stepwise process of plant autophagy with special reference to their crucial role in biotic stress tolerance

Plants, being sessile in nature have evolved to combat pathogenic invasion by judicious utilization of cellular events and re-orchestration of existing metabolic pathways. "Autophagy" is a self-elimination procedure for maintaining cellular equipoise as well as recycling of different cytosolic components. The lysosome is a cell organelle filled with the lytic enzyme that has the capability to destroy self and non-self-biological macromolecules. Cells perspicaciously utilize these suicidal enzymes for the perpetual cycling of materials in the cellular milieu. Autophagy not only degenerates inoperative macromolecules but it also can protect the cells from the deleterious effect of different misfolded proteins. Autophagy may be selective or non-selective. Different organelles e.g., mitochondria, peroxisome, chloroplast, etc. can be selectively atrophied by this process. In plants, autophagy has prodigious functions in cellular fitness to senescence. Recently, it has been demonstrated that biotic stress can also be outlasted by autophagy in plants. So, it has become a propitious mechanism in plants for biotic stress tolerance physiology. The present review intends to discuss the mechanism of plant autophagy with special reference to biotic stress regulation in plants.