Interactions between cotton genotypes and Fusarium wilt race 4 isolates from Texas and resistance evaluation in cotton

Abstract

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.

Use of a Latin square design to assess experimental errors in field evaluation of cotton for resistance to Fusarium wilt Race 4

“…One field near Fabens, TX which was naturally infested with FOV4 and has been used in our studies since 2018 (Zhang, Abdelraheem, Dever, Elkins‐Arce, Wheeler, Zhu et al., 2020; Zhu, Abdelraheem, Wheeler et al., 2021), was used for mapping seedling mortality in 2020. In the field with 202 rows, 64 rows were planted to the susceptible Upland cotton ‘DP 1522 B2XF’ plus eight rows to the highly susceptible ‘Pima DP 357’.…”

“…The concentration of spores was determined using a hemacytometer, and appropriate dilutions were made to obtain a spore suspension with concentration of 10 6 spores ml −1 . The conidial suspension at 1 × 10 6 spores ml −1 is a recommended concentration and has been used in our studies (Abdelraheem et al., 2020, 2021; Zhang, Abdelraheem, Dever, Frelichowski, Wheeler, Zhu et al., 2020; Zhu, Abdelraheem, Lujan et al., 2021; Zhu, Abdelraheem, Wheeler et al., 2021), which induces rapid FW development in susceptible cotton (Hao et al., 2009). Due to high daily temperatures in June 2021, disease symptoms caused by FOV4 developed slowly.…”

“…Fusarium wilt (FW), caused by Fusarium oxysporum f. sp. vasinfectum (FOV) Race 4 (FOV4) has become an important cotton ( Gossypium hirstum ) production problem in the western and southwestern United States (Bell et al., 2019; Halpern et al., 2018; Zhu, Abdelraheem, Lujan et al., 2021; Zhu, Abdelraheem, Wheeler et al., 2021). Fusarium oxysporum f. sp.…”

“…Several commercial transgenic Pima cotton cultivars were reported to be resistant or tolerant to FOV4 through field selections and testing. However, these Pima cultivars still incurred 20 to 40% mortality (Abdelraheem, Dever, Elkins‐Arce, Wheeler, Zhang, Zhu et al., 2020; Zhu, Abdelraheem, Lujan et al., 2021; Zhu, Abdelraheem, Wheeler et al., 2021). Therefore, there is an urgent need to identify and select FOV4‐infested fields for reliable evaluation and effective selection of FOV4 resistance in cotton.…”

Diallel analysis of resistance to Fusarium wilt Race 4 in American pima cotton

“…At the one to two true leaf stage, seedlings were placed into a plastic box for containment of FOV4 and transferred to a temperature‐controlled room at 20 to 23 °C (Zhang, Abdelraheem, Zhu, Wheeler, Dever, Frelichowski, et al., 2020; Zhang et al., 2021). A virulent local FOV4 isolate (JF‐FW‐1A) (Zhang, Abdelraheem, Zhu, Wheeler, Dever, Frelichowski, et al., 2020; Zhu et al., 2020; Zhu, Abdelraheem, Wheeler, et al., 2021) was used as the source of inoculum. Fungal culture and spore quantification followed the protocol described by Zhang et al.…”