A Putative D-Arabinono-1,4-lactone Oxidase, MoAlo1, Is Required for Fungal Growth, Conidiogenesis, and Pathogenicity in Magnaporthe oryzae

Magnaporthe oryzae is the causal agent of rice blast outbreaks. L-ascorbic acid (ASC) is a famous antioxidant found in nature. However, while ASC is rare or absent in fungi, a five-carbon analog, D-erythroascorbic acid (EASC), seems to appear to be a substitute for ASC. Although the antioxidant function of ASC has been widely described, the specific properties and physiological functions of EASC remain poorly understood. In this study, we identified a D-arabinono-1,4-lactone oxidase (ALO) domain-containing protein, MoAlo1, and found that MoAlo1 was localized to mitochondria. Disruption of MoALO1 (Delta Moalo1) exhibited defects in vegetative growth as well as conidiogenesis. The Delta Moalo1 mutant was found to be more sensitive to exogenous H2O2. Additionally, the pathogenicity of conidia in the Delta Moalo1 null mutant was reduced deeply in rice, and defective penetration of appressorium-like structures (ALS) formed by the hyphal tips was also observed in the Delta Moalo1 null mutant. When exogenous EASC was added to the conidial suspension, the defective pathogenicity of the Delta Moalo1 mutant was restored. Collectively, MoAlo1 is essential for growth, conidiogenesis, and pathogenicity in M. oryzae.

Automated summary

The MoAlo1 protein plays a crucial role in vegetative growth, conidiogenesis, and pathogenicity in Magnaporthe oryzae.