Rice false smut (RFS) is one of the most destructive diseases in rice. Its epidemics during recent years not only lead to grain yield loss but also threaten grain quality and safety because of multiple mycotoxins generated by its causal pathogen Ustilaginoidea virens (U. virens). Revealing the infection mechanism of U. virens is crucial to the effective prevention and control of RFS.

In order to better understand the pathogenic mechanism, researchers from China National Rice Research Institute of Chinese Academy of Agricultural Sciences (CNRRI/CAAS) characterized the biological functions of UvKmt2-mediated H3K4me3 modification in U. virens. Phenotypic analyses of the ΔUvkmt2 mutant revealed that UvKMT2 is necessary for growth, conidiation, secondary spore formation, and virulence in U. virens. Immunoblotting and chromatin immunoprecipitation assay followed by sequencing (ChIP-seq) showed that UvKMT2 is required for the establishment of H3K4me3, which covers 1729 genes of the genome in U. virens. Further RNA-seq analysis demonstrated that UvKmt2-mediated H3K4me3 plays a critical role in transcriptional activation. In particular, H3K4me3 modification is involved in the transcriptional regulation of conidiation-related and pathogenic genes, concerning two important mitogen-activated protein kinases UvHOG1 and UvPMK1.

The study reveals that H3K4me3, established by histone methyltransferase UvKmt2, contributes to fungal development, secondary spore formation, virulence, and various stress responses through transcriptional regulation in U. virens. The findings provide clues for developing more effective RFS control strategies.

The National Natural Science Foundation of China, Chinese Academy of Agricultural Sciences under the “Elite Youth” program, and China National Rice Research Institute under the key R&D project and Central Public-Interest Scientific Institution Basal Research Fund supported this work. Results have been published on Journal of Fungi entitled “UvKmt2-Mediated H3K4 Trimethylation Is Required for Pathogenicity and Stress Response in Ustilaginoidea virens”. Researchers from Zhejiang University and Zhejiang Academy of Agricultural Sciences collaborated on the study.

Link to the paper: https://www.mdpi.com/2309-608X/8/6/553/htm