A Cotton (Gossypium Hirsutum) WRKY Transcription Factor (GhWRKY22) Participates in Regulating Anther/pollen Development

Anther/pollen development is a highly programmed process in flowering plants. However, the molecular mechanism of regulating anther/pollen development is still largely unclear so far. Here, we report a cotton WRKY transcription factor (GhWRKY22) that functions in anther/pollen development. Quantitative RT-PCR and GUS activity analyses revealed that GhWRKY22 is predominantly expressed in the late developing anther/pollen of cotton. The transgenic Arabidopsis plants expressing GhWRKY22 displayed the male fertility defect with the fewer viable pollen grains. Expression of the genes involved in jasmonate (JA) biosynthesis was up-regulated, whereas expression of the JA-repressors (JAZ1 and JAZ8) was down-regulated in the transgenic Arabidopsis plants expressing GhWRKY22, compared with those in wild type. Yeast one-hybrid and ChIP-qPCR assays demonstrated that GhWRKY22 modulated the expression of JAZ genes by directly binding to their promoters for regulating anther/pollen development. Yeast two-hybrid assay indicated that GhMYB24 could interact with GhJAZ8-A and GhJAZ13-A. Furthermore, expression of AtMYB24, AtPAL2 and AtANS2 was enhanced in the transgenic Arabidopsis plants, owing to GhWRKY22 overexpression. Taking the data together, our results suggest that GhWRKY22 acts as a transcriptional repressor to regulate anther/pollen development possibly by modulating the expression of the JAZ genes.