A Gene Cassette in Contains Two Genes that Affect Melanized Microsclerotium Formation and Virulence.

is a soilborne phytopathogenic fungus causing Verticillium wilt on hundreds of plant species. Several sequenced genomes of . are available, but functional characterization of most genes has just begun. Based on our previous comparison of the transcriptome from the wild-type and Δ strains, a significant upregulation of the gene cassette, , in the Δ strain was observed. In this study, the functional characterization of the gene cassette was performed. -mediated knockout of this gene cassette in significantly inhibited conidiation, melanized microsclerotium formation in the mutant strains, and their virulence toward cotton. Furthermore, deletion of individual genes in the gene cassette identified that the disruption of and delayed microsclerotium formation, inhibited conidiation, and reduced virulence toward cotton. Our data suggest that and in the gene cassette mainly act as positive regulators of development and virulence in .