Autophagy is a macromolecule degradation pathway in which cellular components are transported to the vacuole to recycle nutrients during nutrient deficiency and senescence and to clear damaged molecules and organelles during environmental stress. Autophagy therefore contributes to plant survival and growth during adverse environmental conditions. Autophagy can be non-selective, indiscriminately degrading cellular components, or selective, in which substrates for autophagy are recognized by receptor proteins and targeted for degradation. Autophagy is active at a low level under normal conditions for homeostasis and is upregulated by many different stresses. We are analyzing the function and regulation of autophagy under different conditions, including its role in homeostatic rRNA degradation under normal growth conditions and in degradation of the endoplasmic reticulum during ER stress. Upstream regulators of autophagy activation have been identified, some of which are common to multiple stresses and some are specific to individual stresses.