N-Acetylglucosamine metabolism is crucial during infectious hyphal growth and virulence of the rice blast fungus Magnaporthe oryzae
A. KUMAR (1), S. Ghosh (2), D. Bhatt (3), A. Narurla (4), A. Datta (3) (1) National Institute of Plant Genome Research (NIPGR), India; (2) Central Institute of Medicinal and Aromatic Plants, India; (3) National Institute of Plant Genome Research, India; (4) Hamdard University, India

A pathogen must acquire suitable nutrients from the host cell in order to proliferate. However, our knowledge on essential nutrients for the invading pathogens during plant infection is limited. We identified a cluster of genes that is involved in N-acetylglucosamine (GlcNAc) catabolism in rice pathogen Magnaporthe oryzae and several other phytopathogenic fungi. To determine the association of GlcNAc catabolism with M. oryzae pathogenesis, GlcNAc-6-phosphate deacetylase (MoDac), GlcN-6-phosphate deaminase (MoDeam), and a GlcNAc transporter (MoNgt1) are functionally characterized. M. oryzae mutants lacking MoDac, MoDeam and MoNgt1 were compromised in GlcNAc utilization and exhibited reduced virulence towards the blast susceptible rice cultivar owing to the failure to develop invasive hyphal growth within the host tissues. These mutants were unable to neutralize reactive oxygen species (ROS) at the infection sites. Although GlcNAc was beneficial to the wild type strain under ROS stress, it inhibited growth of the ?modac and ?modeam mutants and the growth inventory effect was further pronounced under ROS stress. These results suggest that GlcNAc helps fungus to overcome oxidative stress inside the host, perhaps by activating anti-oxidant defense, and in absence of a functional catabolic pathway, GlcNAc becomes toxic to the cells. Altogether, these results suggest that GlcNAc metabolism is essential for the M. oryzae to sustain in planta growth.

Abstract Number: P9-272
Session Type: Poster