Autophagy in plants: molecular mechanisms and roles in abiotic stress responses

Autophagy is an evolutionarily conserved catabolic pathway that maintains cellular homeostasis by degrading and recycling cytoplasmic components in the vacuole or lysosome. In plants, this process is indispensable for nutrient remobilization and stress acclimation, clearing dysfunctional organelles, protein aggregates, and other cytoplasmic material. This review covers current knowledge of plant autophagy, beginning with the core ATG (autophagy-related) machinery and the mechanisms of selective cargo recognition mediated by receptors such as NBR1 and the ATG8 protein family, then extending to organelle-specific degradation pathways including chlorophagy, mitophagy, and ER (endoplasmic reticulum)-phagy. We examine how autophagy supports plant survival under adverse conditions with attention to the regulatory networks governing autophagic activity, including the antagonistic TOR (Target of Rapamycin) and SnRK1 (Sucrose Non-Fermenting Related Kinase 1) kinase pathways that act as central nutrient and energy sensors. Collectively, these findings establish autophagy not merely as a cellular housekeeping mechanism, but as a central regulatory hub that coordinates plant growth with environmental adaptation, with important implications for engineering stress-resilient crops.