Molecular and Disease Characterization of Verticillium Dahliae Isolates from China

Verticillium wilt is a serious disease of cotton in cooler cotton producing areas in the world. For effective management of the disease, it is imperative to know the underlying pathogen population. In 2015, we collected stem sections from wilted plants from seven counties of Southern and Northern Xinjiang regions in China. The stems were allowed to dry and shipped to USDA-ARS Cotton Pathology lab in College Station, TX. Stems were surface sterilized, cut in half, and placed on Komada medium. Seventy-eight fungal isolates were obtained and found to be Verticillium dahliae. All belonged to mating type MAT1-2 by PCR analysis. The isolates were divided into several genotypes based on PCR amplification with primers to VdD (defoliating), VdND (non-defoliating), VdAve1 (race 1) and race 2. The VdAve1 PCR product was not detected in these isolates. The race 2 PCR product was amplified from most of the isolates. The isolates were separated based on VdD and VdND amplification. Sequencing of four loci including the PHO and Ligase genes was used to further genotype the isolates. Disease assays using stem puncture inoculation of Acala 44 was used to differentiate and validate molecular genotyping of defoliating and non-defoliating isolates. These results will be summarized at Beltwide 2020.