To better understand the evolution of virulence we are interested in identifying the genetic basis of this trait in pathogenic fungi and in developing tools for the rapid characterization of variation in virulence among populations associated with epidemics. Fusarium oxysporum f. sp. vasinfectum (FOV) is a haploid fungus that causes devastating outbreaks of Fusarium wilt of cotton wherever it is grown. In the United States, six nominal races and eleven genotypes of FOV have been characterized based on the translation elongation factor (EF-1α) gene and intergenic spacer region (IGS), but it is unclear how race or genotype based on these regions relates to population structure or virulence. We used genotyping-by-sequencing to identify SNPs and determine genetic diversity and population structure among 86 diverse FOV isolates. Six individuals of Fusarium oxysporum closely related to FOV were genotyped and included in some analyses. Between 193 and 354 SNPs were identified and included in the analyses depending on the pipeline and filtering criteria used. Phylogenetic trees, minimum spanning networks (MSNs), principal components analysis (PCA), and discriminant analysis of principal components (DAPC) demonstrated that races and genotypes of FOV are generally not structured by EF-1α genotype, nor are they monophyletic groups with the exception of race 4 isolates, which are distinct. Furthermore, DAPC identified between 11 and 14 genetically distinct clusters of FOV, whereas only eight EF-1α genotypes were represented among isolates; suggesting that FOV, especially isolates within the widely distributed and common race 1 genotype, is more genetically diverse than currently recognized.

为了更好地了解毒力的演变，我们感兴趣的是确定病原性真菌中该性状的遗传基础，并研究开发工具以快速表征与流行病相关的人群中毒力的变化。尖孢镰刀菌f。sp。vasinfectum（FOV）是一种单倍体真菌，无论生长在何处，都会引起毁灭性的棉花枯萎病爆发。在美国，已根据翻译延伸因子（EF-1α）鉴定了6个名义种族和11个FOV基因型基因和基因间隔区（IGS），但目前尚不清楚基于这些区域的种族或基因型如何与种群结构或毒力相关。我们通过测序进行基因分型来鉴定SNP，并确定86种FOV分离株之间的遗传多样性和种群结构。对6个与FOV密切相关的尖孢镰刀菌进行了基因分型并纳入了一些分析。根据所使用的管线和过滤标准，确定了193至354个SNP，并将其包括在分析中。系统发育树，最小生成网络（MSN），主成分分析（PCA）和主成分判别分析（DAPC）表明，EF-1α通常不构成FOV的种族和基因型基因型，它们也不是单基因组，只有种族4分离株除外。此外，DAPC鉴定出11至14个FOV遗传上不同的簇，而分离株中只有8个EF-1α基因型。这表明FOV，尤其是广泛分布的通用第1种种族基因型中的分离物，在遗传上比目前公认的更具多样性。