ATG8 delipidation is dispensable for plant autophagy

Abstract Intracellular recycling via autophagy is governed by post-translational modifications of the autophagy related (ATG) proteins. One example is ATG4-dependent delipidation of ATG8, which assumes critical but distinct roles in autophagosome formation of yeast and mammals. Here, we discovered that ATG8 delipidation is dispensable for the maturation of autophagosomes, autophagic flux and related stress tolerance in Arabidopsis. In contrast, autophagy in an evolutionary distant Chlamydomonas strictly required ATG4-dependent ATG8 delipidation. Additionally, we uncovered distinct participation of Arabidopsis ATG8 orthologs in autophagosome biogenesis, especially prevalent under nitrogen depletion, thereby providing new insights into potential reasons behind ATG8 gene family expansion in vascular plants. Our findings point to evolutionary diversification of the molecular mechanism governing maturation of autophagosomes in eukaryotic lineages and highlight how this conserved pathway is tailored to diverse eukaryotic organisms.