A novel transcription factor UvCGBP1 regulates development and virulence of rice false smut fungus <i>Ustilaginoidea virens</i>

<i>Ustilaginoidea virens</i>, causing rice false smut (RFS) is an economically important ascomycetous fungal pathogen distributed in rice-growing regions worldwide. Here, we identified a novel transcription factor UvCGBP1 (Cutinase G-box binding protein) from this fungus, which is unique to ascomycetes. Deletion of <i>UvCGBP1</i> affected development and virulence of <i>U. virens</i>. A total of 865 downstream target genes of UvCGBP1 was identified using ChIP-seq and the most significant KEGG enriched functional pathway was the MAPK signaling pathway. Approximately 36% of target genes contain the AGGGG (G-box) motif in their promoter. Among the targets, deletion of <i>UvCGBP1</i> affected transcriptional and translational levels of <i>UvPmk1</i> and <i>UvSlt2</i>, both of which were important in virulence. ChIP-qPCR, yeast one-hybrid and EMSA confirmed that UvCGBP1 can bind the promoter of <i>UvPmk1</i> or <i>UvSlt2</i>. Overexpression of <i>UvPmk1</i> in the <i>∆UvCGBP1-33</i> mutant restored partially its virulence and hyphae growth, indicating that UvCGBP1 could function via the MAPK pathway to regulate fungal virulence. Taken together, this study uncovered a novel regulatory mechanism of fungal virulence linking the MAPK pathway mediated by a G-box binding transcription factor, UvCGBP1.