FIGURE 1.

Schematic of the three types of autophagy in plants. (A) In macroautophagy, a cup-shaped phagophore is formed and closes into vesicular autophagosomes as it encircles cytosolic substances. The autophagosome is subsequently delivered to the vacuole. The outer membrane of the autophagosome fuses with the tonoplast and the internal vesicle is released to the vacuolar lumen for degradation. (B) In microautophagy, cytosolic materials are gathered on the tonoplast and directly captured by the vacuole through invagination to be degraded. (C) During mega-autophagy, the vacuolar membrane is permeabilized and ruptures, releasing large amounts of hydrolases into the cytoplasm, causing indiscriminate degradation of cytoplasmic materials.