Chlorophagy is ATG gene-dependent microautophagy process

Autophagy delivers cytosolic components to lysosomes and the vacuole for degradation. This pathway prevents starvation through bulk degradation and recycling of cytoplasmic components, and maintains cellular homeostasis through selective elimination of damaged proteins and organelles. Autophagic delivery processes are categorized into three types: macroautophagy, microautophagy, and chaperone-mediated autophagy. During macroautophagy, nascent, double membrane–bound vesicles termed autophagosomes sequester a portion of cytoplasm and deliver it to the vacuole/lysosomes. Molecular genetic studies in budding yeasts have identified a set of AUTOPHAGY (ATG) genes required for autophagosome formation. Although microautophagy involves the direct lysosomal/vacuolar engulfment and incorporation of a target into the lumen rather than the formation of autophagosomes, the membrane dynamics and possible roles of ATGs during microautophagy are under investigation. Our recent study revealed an ATG-dependent microautophagy process in plants, during which chloroplasts damaged by high visible light (HL) are selectively eliminated. Here, we discuss the membrane dynamics of the plant microautophagy that enables the transport of whole chloroplasts into the vacuole.