Magnaporthe oryzae MoNdt80 is a transcriptional regulator of GlcNAc catabolic pathway involved in pathogenesis

Availability and efficient utilization of host-derived nutrients by pathogens decide the fate of host-pathogen interaction. In Magnaporthe oryzae, N-acetylglucosamine (GlcNAc) catabolic pathway was found essential for successful host colonization and pathogenicity. GlcNAc catabolic enzymes hexokinase, GlcNAc-6-phosphate deacetylase (MoDac) and GlcN-6-phosphate deaminase (MoDeam) are encoded in a genomic cluster in M. oryzae and several phytopathogenic fungi. However, transcriptional regulation of GlcNAc catabolic pathway was not understood. We identified a conserved Ndt80/PhoG-like transcriptional regulator as a part of the GlcNAc catabolic gene cluster in M. oryzae and other fungi. We found that MoNdt80 is essential for GlcNAc utilization and pathogenicity of M. oryzae. Unlike WT, Delta MoNdt80 failed to induce transcription of GlcNAc catabolic pathway genes in response to GlcNAc. MoNdt80 could bind to a specific cis-acting consensus sequence GNCRCAAA[AT], present in the promoter of MoDac, MoDeam and beta-hexosaminidase (MoHex). Further, comparative RNA-sequencing analysis using WT and Delta MoNdt80 revealed a large set of GlcNAc responsive genes that are under the transcriptional control of MoNdt80. These genes encoded GlcNAc catabolic enzymes, transporters and cell wall degrading enzymes which are required for hyphal growth expansion during host colonization. Overall, these results suggest MoNdt80 mediated transcriptional regulation of GlcNAc catabolic pathway is essential for successful host colonization and pathogenesis.