GhWRKY207 improves drought tolerance through promoting the expression of GhCSD3 and GhFSD2 in Gossypium hirsutum

Tryptophan-arginine-lysine-tyrosine (WRKY) transcription factors are essential regulators of drought tolerance in multiple plants. However, whether and how GhWRKY207 modulates cotton response to drought stress is unclear. In this study, we determined that GhWRKY207 expression was high in leaves and induced by drought stress. The gene encoded a nuclear protein that had transcriptional activation activity. Silencing GhWRKY207 by virus-induced gene silencing (VIGS) caused significant reduction in drought tolerance of cotton plants. Consistently, overexpression of GhWRKY207 in Arabidopsis thaliana wild type (WT) plants clearly enhanced their drought tolerance. Moreover, GhWRKY207 VIGS plants had notably increased malondialdehyde (MDA) contents, electrolyte leakage percentages and O₂^·- accumulation rates whereas GhWRKY207 overexpression lines showed markedly decreased levels of the three parameters compared to their corresponding controls under water deficit conditions. Additionally, GhWRKY207 enhanced superoxide dismutase (SOD) activity by directly activating the expression of GhCu/Zn-SOD3 (GhCSD3) and GhFe-SOD2 (GhFSD2) genes. Silencing GhCSD3 or GhFSD2 also markedly reduced drought tolerance of cotton plants. Taken together, these results suggest that GhWRKY207 positively regulates drought tolerance by inducing the expression of GhCSD3 and GhFSD2 in Gossypium hirsutum.