P-150 - Deciphering the coordinated regulation of gene silencing and pathogenicity by histone methylations in a plant fungal pathogen Verticillium dahliae

In eukaryotes, histone modifications H3K9me and H3K27me have traditionally been viewed as independent pathways, each governed by distinct complexes. However, recent studies suggest these modifications can co-occur at the same gene locus, indicating potential complementarity and synergy. To explore this coordinated regulation, we used Verticillium dahliae, a fungal pathogen known for both modifications and its role in severe plant vascular diseases.

By mutating the histone H3K9me and H3K27me methyltransferases, VdKMT1 and VdEZH2, we observed significant upregulation of numerous genes, highlighting the importance of these modifications in gene silencing. Using in situ labeling, complex extraction, and mass spectrometry, we identified and confirmed the interactions of the core components of these complexes.

We further employed CUT&tag-seq to measure H3K9me3 and H3K27me3 levels in VdΔKMT1 and VdΔEZH2 mutants, respectively, and integrated these data with transcriptome sequencing. Our findings revealed that H3K9me3 indirectly regulates gene expression by modulating H3K27me3 levels. Additionally, phenotypic and histone modification analyses of VdΔEZH2 and VdΔRbAP48 suggest that VdRbAP48 can recruit VdKMT1 to serve as an H3K27 methyltransferase when VdEZH2 is mutated. Importantly, the VdKMT1 mutant exhibited reduced pathogenicity, presenting a potential molecular target for cross-kingdom RNAi strategies to control V. dahliae.