A dual component system instructs membrane hydrolysis during the final stages of plant autophagy

Abstract

Autophagy is an intracellular catabolic process conserved across eukaryotes and critical for plant stress tolerance. Upon their delivery in the vacuole, how autophagic bodies containing cargo are hydrolyzed to warrant autophagy degradation remains poorly characterized. Here, we identify two Arabidopsis phospholipases as core components of the autophagy machinery. We find that LCAT3 and LCAT4 traffic to the vacuolar lumen and converge on autophagic bodies using differential pathways, placing them on the outer and inner side of the vesicle, respectively. Double knockouts lcat3,4 accumulate autophagic bodies and show reduced autophagy activity. In vivo reconstitution demonstrates that LCAT3 can hydrolyze the membrane of autophagic bodies, enabling the activity of LCAT4 to enhance this process. In sum, our work reveals that the concerted action of a multi-component system is required for the efficient and specific disruption of autophagic bodies as an obligatory step for the completion of the autophagy pathway.