The cotton WRKY transcription factor GhWRKY70 negatively regulates the defense response against Verticillium dahliae

WRKY transcription factors (TFs) play important roles in the regulation of biotic and abiotic stresses. However, the functions of most WRKY TFs in upland cotton (Gossypium hirsutum) are still unknown. In this study, we functionally identified a group III WRKY transcription factor, GhWRKY70, in upland cotton. Reverse transcription-quantitative PCR analysis showed that GhWRKY70 expression was induced by Verticillium dahliae, salicylic acid (SA) and methyl jasmonate. Virus-induced gene silencing of GhWRKY70 increased the resistance of cotton to V. dahliae. Specifically, jasmonic acid (JA) response-associated genes were upregulated and SA-related genes were downregulated in GhWRKY70-silenced cotton plants. Overexpression of GhWRKY70 reduced tolerance to V. dahliae in Arabidopsis thaliana. Transgenic Arabidopsis plants showed increased expression of SA-associated genes and reduced expression of JA response-associated genes. These results suggest that GhWRKY70 negatively regulates tolerance to V. dahliae in at least two ways: (i) by upregulating the expression of SA-associated genes and (ii) by reducing the expression of JA-associated genes.