The Magnaporthe oryzae RSR1 gene regulates fungal antioxidation and is essential for host ROS neutralization during rice cell invasion
L. SEGAL (1), R. Wilson (1) (1) University of Nebraska-Lincoln, U.S.A.

Magnaporthe oryzae is the causal agent of rice blast disease. Tolerating oxidative stress by neutralizing the host reactive oxygen species (ROS) burst is key to the intracellular survival and proliferation of M. oryzae in rice cells. Thus, understanding how fungal antioxidation genes are controlled during infection might shed new light on the early fungal-plant interaction. In this study, we sought to identify additional components of the M. oryzae oxidative defense pathway that are under the control of the glucose-6-phosphate (G6P) sensing trehalose-6-phosphate synthase 1 (Tps1) protein. Here, we report the functional characterization of a new regulator of Tps1-dependent antioxidation gene expression, RSR1. Δrsr1 mutant strains were altered for antioxidation gene expression, increased for radial growth under oxidative stress conditions, and reduced for pathogenicity compared to wild type. Drsr1 mutant strains formed functional appressoria on rice leaf surfaces but were unable to proliferate in planta or overcome host ROS bursts, likely due to misregulated antioxidation gene expression. Taken together, this work adds new signaling components to the Tps1-dependent antioxidation pathway and enhances our understanding of the crucial importance of fungal redox homeostasis to the plant infection process.

Abstract Number: P7-210
Session Type: Poster