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

Abstract

Improving plant resistance to Verticillium wilt (VW), which causes massive losses in Gossypium hirsutum, is a global challenge. Crop plants need to efficiently allocate their limited energy resources to maintain a balance between growth and defense. However, few transcriptional regulators specifically respond to Verticillium dahliae and the underlying mechanism has not been identified in cotton. In this study, we found that the that expression of most R2R3-MYB members in cotton is significantly changed by V. dahliae infection relative to the other MYB types. One novel R2R3-MYB transcription factor (TF) that specifically responds to V. dahliae, GhMYB3D5, was identified. GhMYB3D5 was not expressed in 15 cotton tissues under normal conditions, but it was dramatically 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 to the GhADH1 promoter and activated GhADH1 expression. In addition, GhMYB3D5 physically interacted with GhADH1 and further enhanced the transcriptional activation of GhADH1. Consequently, the transcriptional regulatory module GhMYB3D5-GhADH1 then promoted lignin accumulation by improving the transcriptional levels of genes related to lignin biosynthesis (GhPAL, GhC4H, Gh4CL, and GhPOD/GhLAC) in cotton, thereby enhancing cotton VW resistance. Our results demonstrated that the GhMYB3D5 promotes defense-induced lignin accumulation, which can be regarded as an effective way to orchestrate plant immunity and growth.

Keywords

• cotton
• Verticillium wilt resistance
• GhMYB3D5
• GhADH1
• transcriptional regulatory module