Verticillium dahliae chromatin remodeling facilitates the DNA damage repair in response to plant ROS stress.

Reactive oxygen species (ROS) production is one of the earliest responses when plants percept pathogens and acts as antimicrobials to block pathogen entry. However, whether and how pathogens tolerate ROS stress remains elusive. Here, we report the chromatin remodeling in Verticillium dahliae, a soil-borne pathogenic fungus that causes vascular wilts of a wide range of plants, facilitates the DNA damage repair in response to plant ROS stress. We identified VdDpb4, encoding a histone-fold protein of the ISW2 chromatin remodeling complex in V. dahliae, is a virulence gene. The reduced virulence in wild type Arabidopsis plants arising from VdDpb4 deletion was impaired in the rbohd mutant plants that did not produce ROS. Further characterization of VdDpb4 and its interacting protein, VdIsw2, an ATP-dependent chromatin-remodeling factor, we show that while the depletion of VdIsw2 led to the decondensing of chromatin, the depletion of VdDpb4 resulted in a more compact chromatin structure and affected the VdIsw2-dependent transcriptional effect on gene expression, including genes involved in DNA damage repair. A knockout mutant of either VdDpb4 or VdIsw2 reduced the efficiency of DNA repair in the presence of DNA-damaging agents and virulence during plant infection. Together, our data demonstrate that VdDpb4 and VdIsw2 play roles in maintaining chromatin structure for positioning nucleosomes and transcription regulation, including genes involved in DNA repair in response to ROS stress during development and plant infection. Author summary: ROS production is one of the earliest responses after the perception of pathogen-associated molecular patterns by plant transmembrane immune receptors, and dependent on the respiratory burst oxidase homolog (RBOH). ROS cause DNA oxidative damage and acts as antimicrobials to block pathogen entry. In this study, we found that chromatin remodeling components, including VdPdb4 and its interacting protein, VdIsw2, are essential for the V. dahliae tolerant in response to ROS stress during development and plant infection. Assays of the accessibility of bulk chromatin suggest that VdDpb4 plays an important role in maintaining a more "open" and accessible chromatin landscape, while VdIsw2 plays an antagonistic role in balancing chromatin structure. Abnormality of nucleosome repositioning by depletion of either protein is harmful to the fungus during DNA repair in response to ROS stress during development and plant infection. We further found that VdDpb4 is required for VdIsw2 to bind to gene promoters for appropriate RNA polymerase II transcription. Taken together, our data demonstrate that VdDpb4 is required for the location of ISW2 on DNA and VdIsw2-dependent transcriptional regulation of gene expression; and provide the first example and essential information for further investigation of chromatin-associated complexes in pathogenic fungi. [ABSTRACT FROM AUTHOR]