GhERF.B4-15D: A Member of ERF Subfamily B4 Group Positively Regulates the Resistance against Verticillium dahliae in Upland Cotton.

Verticillium wilt is a fungal disease in upland cotton and exerts a significant effect on growth and potential productivity. This disease is mainly caused by V. dahliae Kleb. Ethylene response factor (ERF) is one of the superfamilies of transcription factors that is involved in the development and environmental adaption of crops. A total of 30 ERF.B4 group members were detected in upland cotton and divided into 6 subgroups. Gene structures, conserved motifs, and domain analysis revealed that members in each subgroup are highly conserved. Further, the 30 GhERF.B4 group members were distributed on 18 chromosomes, and 36 gene synteny relationships were found among them. GhERF.B4 genes were ubiquitously expressed in various tissues and developmental stages of cotton. Amongst them, GhERF.B4-15D was predominantly expressed in roots, and its expression was induced by V. dahliae infection. In addition, GhERF.B4-15D responded to methyl jasmonate (MeJA), methyl salicylate (MeSA), and ethylene (ET) phytohormones. It was also found that the V. dahliae resistance was enhanced due to overexpression of GhERF.B4-15D in Arabidopsis thaliana. On the contrary, interference of GhERF.B4-15D by virus-induced gene silencing (VIGS) technology decreased the V. dahliae resistance level in upland cotton. The subcellular localization experiment showed that GhERF.B4-15D was located in the nucleus. Yeast two-hybrid (Y2H) and luciferase complementation (LUC) approaches demonstrated that GhERF.B4-15D interacted with GhDREB1B. Additionally, the V. dahliae resistance was significantly decreased in GhDREB1B knockdowns. Our results showed that GhERF.B4-15D plays a role during V. dahliae infection in cotton.