A vacuolar glucoamylase, Sga1, participates in glycogen autophagy for proper asexual differentiation in Magnaporthe oryzae

作者：Deng Yi Zhen; Naqvi Naweed I^*

来源：Autophagy, 2010, 6(4): 455-461.

• autophagy
• Sga1
• Magnaporthe
• glycogen
• asexual reproduction
• conidia
• rice-blast

Nutrient limitation acts as a trigger for the synthesis of glycogen, which serves as a carbon and energy reserve during starvation. Recently, we reported that an autophagy-deficient mutant (atg Delta) shows severe reduction in aerial hyphal growth and conidiation in the rice-blast fungus Magnaporthe oryzae, and proposed that autophagy plays an important role in facilitating glycogen homeostasis to ensure proper asexual differentiation in Magnaporthe. Here, we identify and characterize a vacuolar glucoamylase Sga1) that hydrolyses glycogen to meet the energy requirements during asexual development in Magnaporthe. Loss of SGA1 resulted in significant reduction in conidiation compared to the wild-type Magnaporthe strain. More importantly, an sga1 Delta atg8 Delta double deletion mutant showed further reduction in conidiation compared to the atg8 Delta mutant in Magnaporthe. Forced localization of GFP-Sga1 to the cytoplasm ( through removal of the predicted signal peptide) led to increased conidiation in wild type and the sga1 Delta, but more interestingly, significantly restored conidiation in the atg8 Delta mutant. Our results indicate that autophagy and Sga1 act cooperatively in vacuolar glycogen breakdown, which is essential for conidia formation but dispensable for pathogenicity in Magnaporthe.

• 出版日期2010-5-16