Inhibition of Pathogenicity of the Rice Blast Fungus by Saccharomyces cerevisiae α-Factor

Abstract

Magnaporthe grisea is a fungal pathogen with two mating types, MAT1-1 and MAT1-2 , that forms a specialized cell necessary for pathogenesis, the appressorium. Saccharomyces cerevisiae α-factor pheromone blocked appressorium formation in a mating type–specific manner and protected plants from infection by MAT1-2 strains. Experiments with α-factor analogs suggest that the observed activity is due to a specific interaction of α-factor with an M. grisea receptor. Culture filtrates of a MAT1-1 strain contained an activity that inhibited appressorium formation of mating type MAT1-2 strains. These findings provide evidence that a pheromone response pathway exists in M. grisea that can be exploited for plant protection.