Autophagy-related protein MoAtg14 is involved in differentiation, development and pathogenicity in the rice blast fungus Magnaporthe oryzae

Autophagy is the major intracellular degradation system by which cytoplasmic materials are delivered to and degraded in the vacuole/lysosome in eukaryotic cells. MoAtg14 in M. oryzae, a hitherto uncharacterized protein, is the highly divergent homolog of the yeast Atg14 and the mammal BARKOR. The MoATG14 deletion mutant exhibited collapse in the center of the colonies, poor conidiation and a complete loss of virulence. Significantly, the Delta Moatg14 mutant showed delayed breakdown of glycogen, less lipid bodies, reduced turgor pressure in the appressorium and impaired conidial autophagic cell death. The autophagic process was blocked in the Delta Moatg14 mutant, and the autophagic degradation of the marker protein GFP-MoAtg8 was interrupted. GFP-MoAtg14 co-localized with mCherry-MoAtg8 in the aerial hypha. In addition, a conserved coiled-coil domain was predicted in the N-terminal region of the MoAtg14 protein, a domain which could mediate the interaction between MoAtg14 and MoAtg6. The coiled-coil domain of the MoAtg14 protein is essential for its function in autophagy and pathogenicity.