Genetic diversity and virulence of Fusarium oxysporum f. sp. vasinfectum (FOV) races causing Fusarium wilt of cotton in the southeastern United States
Hannah Halpern: University of Georgia
<div><em>Fusarium oxysporum </em>f. sp. <em>vasinfectum</em> (FOV), the fungus that causes Fusarium wilt of cotton (<em>Gossypium </em>spp.), has recently caused devastating outbreaks in the southeastern United States. FOV is genetically and pathogenically diverse, with six nominal races and eleven distinct genotypes based on sequences at the partial translation elongation factor (<em>EF-1</em><em>a)</em> locus and intergenic spacer region (IGS). Some genotypes of FOV are more virulent on cotton than others, and some require plant pathogenic nematodes for virulence. Our research objectives are to: 1) understand how populations of FOV are evolving in the southeastern United States by determining how different genotypes of FOV are related, and 2) understand the relationship between FOV genotype and disease phenotype. We used genotyping-by-sequencing (GBS) to identify SNP variants across 160 genetically, geographically, and temporally diverse FOV isolates. Unique SNP genotypes were used to construct a maximum likelihood tree and to perform K-means hierarchical clustering. We also conducted greenhouse assays to test for differences in virulence among genotypes. Forty-five genetically diverse isolates were inoculated onto three cotton cultivars with differing susceptibilities to FOV. Our results show that there is high genetic diversity in FOV, and some clustering based on previously described races. Additionally, some genotypes of FOV are associated with distinct disease phenotypes on cotton.</div>
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