Cotton leaf curl Multan virus βC1 Protein Induces Autophagy by Disrupting the Interaction of Autophagy-Related Protein 3 with Glyceraldehyde-3-Phosphate Dehydrogenases

Autophagy is known to play an important role in plant-pathogen interactions. Several pathogens including viruses are reported to induce autophagy in plants, but the underpinning mechanism remains largely unclear. Further, in virus-plant interplay it is yet to identify any viral factor(s) responsible for induction of autophagy. Here, we report that βC1 protein of Cotton leaf curl Multan betasatellite (CLCuMuB) interacts with cytosolic glyceraldehyde-3-phosphate dehydrogenases (GAPCs), a negative autophagic regulator, to induce autophagy in plants. CLCuMuB βC1 bound to GAPCs and disrupted the interaction between GAPCs and ATG3. A mutant βC1 protein (βC13A) in which I45, Y48, and I53 were all substituted with alanine (A), dramatically reduced its binding capacity with GAPCs, failed to disrupt the GAPCs-ATG3 interactions and failed to induce autophagy. Furthermore, mutant virus carrying βC13A showed increased symptoms and viral DNA accumulation associated with decreased autophagy in plants. These results suggest that CLCuMuB βC1 activates autophagy by disrupting GAPCs-ATG3 interactions.