Study Uncovers Epigenetic Mechanism in the Regulation of Phytopathogenic Fungal Virulence

This study is led by Dr Cheng-Guo Duan (Center of Excellence in Molecular Plant Sciences, Chinese Academy of Sciences). As a conserved epigenetic mark, DNA cytosine methylation at 5' position (5-mC) plays important roles in multiple biological processes including plant immunity. While, it remains still elusive about the involvement of DNA methylation in the determinants of virulence of phytopathogenic fungi. Verticillium dahliae, one of the major causal pathogens of Verticillium wilt disease that causes great losses in many crops, has a wide host range. Due to the lack of natural disease-resistant germplasm resources, discovering effective virulence genes is crucial for cultivating wilt disease-resistant cotton.

The team investigated the DNA methylation profiles of V. dahliae and its contribution in fungal pathogenicity. The major enzymes responsible for the establishment of DNA methylation in V. dahliae were identified. The researchers demonstrated that DNA methylation is indispensable for the penetration and colonization of V. dahliae in plants through inhibiting the expression of stress-responsive protein kinase VdRim15, which is involved in the regulation of ROS and Ca2+ accumulation in penetration peg.

Intriguingly, H3K9me3, another heterochromatin modification that often co-localizes with 5-mC, coordinates with 5-mC in the regulation of V. dahliae virulence, and the DNA and H3K9 methyltransferase genes were greatly induced in the early stage of fungal infection, implying that a dynamic regulation of 5-mC and H3K9me3 homeostasis is required for the efficient infection. Collectively, this study uncovers an epigenetic mechanism in the regulation of phytopathogenic fungal virulence, and provided a valuable virulence target for cotton wilt disease resistance breeding.