Fusarium wilt, caused by the soil-borne fungus Fusarium oxysporum f. sp. vasinfectum (FOV) race 4 (FOV4), is one of the most destructive diseases in cotton (Gossypium spp.) in the southwestern and western Cotton Belt. However, the virulence of FOV4 is currently unknown. In this study, 17 FOV isolates collected in the Fabens, TX, area were determined to be FOV4 based on FOV4-specific polymerase chain reaction (PCR) and sequence analysis of three genes encoding for translation elongation factor, β-tubulin, and phosphate permease. A further multiplex PCR analysis determined that they all belonged to the Tfo1/MULE MT genotype. Based on disease severity ratings (DSR) on two upland and two pima cotton lines in the greenhouse, virulence of the 17 FOV4 isolates differed but was overall congruent on the four lines, and differences among cotton genotypes accounted for 82% of the total variance. Variance in virulence due to FOV4 isolates and FOV4 isolate × cotton genotype interaction each accounted for only 8–11% of the total variance. A virulent MT FOV4 isolate was used to inoculate 104 entries representing 92 cultivars and elite lines in two tests at 21–23 °C. The combined ANOVA detected a significant genotypic variation in DSR with moderate broad-sense heritability estimates (.62–.69). About 90–91% of the genotypes were susceptible to FOV4, including 100% mortality in 59–91% of the genotypes. Pima PHY 805 RF and three upland cultivars including FM 2334GLT, Acala 1517-08, and Acala Daytona RF had similar resistance responses to the resistant check pima PHY 841 RF. This study demonstrated that cotton genotypes played a predominant role in determining FOV4 virulence, reinforcing the validity of using a representative isolate to screen cotton for FOV4 resistance.

中文翻译：

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棉花基因型与德克萨斯枯萎病4号分离株的互作及棉花抗性评价

枯萎病，由土传真菌尖孢镰刀菌f 引起。sp. vasinfectum (FOV) 种族 4 (FOV4) 是西南和西部棉带的棉花 ( Gossypium spp.) 中最具破坏性的病害之一。然而，FOV4 的毒力目前未知。在这项研究中，基于 FOV4 特异性聚合酶链反应 (PCR) 和编码翻译延伸因子、β-微管蛋白和磷酸渗透酶的三个基因的序列分析，在德克萨斯州法本斯地区收集的 17 个 FOV 分离株被确定为 FOV4 . 进一步的多重 PCR 分析确定它们都属于Tfo1/MULEMT 基因型。根据温室中两个陆地棉和两个比马棉品系的疾病严重程度等级 (DSR)，17 个 FOV4 分离株的毒力不同，但在四个品系上总体一致，棉花基因型之间的差异占总方差的 82%。FOV4 分离株和 FOV4 分离株 × 棉花基因型相互作用引起的毒力变异各仅占总变异的 8-11%。在 21–23 °C 下的两次测试中，使用有毒的 MT FOV4 分离株接种了代表 92 个品种和优良品系的 104 个条目。组合方差分析检测到 DSR 中的显着基因型变异，具有中等广义遗传力估计值 (.62–.69)。大约 90-91% 的基因型对 FOV4 敏感，其中 59-91% 的基因型死亡率为 100%。Pima PHY 805 RF 和三个高地栽培品种，包括 FM 2334GLT，Acala 1517-08 和 Acala Daytona RF 对抗性检查 pima PHY 841 RF 具有相似的抗性响应。该研究表明，棉花基因型在确定 FOV4 毒力方面发挥了主要作用，加强了使用代表性分离株筛选棉花的 FOV4 抗性的有效性。