Expression analysis of the R2R3-MYB gene family in upland cotton and functional study of GhMYB3D5 in regulating Verticillium wilt resistance

Improving plant resistance to Verticillium wilt (VW), which causes massive losses in Gossypium hirsutum, is a global challenge. Crop needs to efficiently allocate their limited energy resources to balance growth and defense. However, few transcriptional regulators specifically response to V. dahliae and the underlying mechanism in cotton has not been identified. In this study, we found that the that expression of the majority R2R3-MYB in cotton is significantly changed relative to other MYB types by V. dahliae infection. Of which, a novel R2R3-MYB TF GhMYB3D5, specifically response to V. dahliae, was identified. GhMYB3D5 did not express across 15 cotton tissues at normal condition, but drastically induced by V. dahliae stress. We functionally characterized its positive role and underlying mechanism in VW resistance. Upon V. dahliae infection, the up-regulated GhMYB3D5 bound the GhADH1 promoter and activated GhADH1 expression, moreover, GhMYB3D5 physically interacted with GhADH1 and furtherly enhanced the transcriptional activation to GhADH1. Consequently, the transcriptional regulatory module GhMYB3D5-GhADH1 promoted lignin accumulation via improving the transcriptional levels of genes related to lignin biosynthesis (GhPAL, GhC4H, Gh4CL, and GhPOD/GhLAC) in cotton, thereby enhancing the cotton VW resistance. Taken together, our results demonstrated that the GhMYB3D5 promoted a defense-induced lignin accumulation, which regarded as an effective manner in orchestrating plant immunity and growth.