Arabidopsis WRKY 2 and WRKY 34 transcription factors interact with VQ 20 protein to modulate pollen development and function

Summary Plant male gametogenesis is tightly regulated, and involves complex and precise regulations of transcriptional reprogramming. WRKY transcription factors have been demonstrated to play critical roles in plant development and stress responses. Several members of this family physically interact with VQ motif‐containing proteins ( VQ proteins) to mediate a plethora of programs in Arabidopsis; however, the involvement of WRKY – VQ complexes in plant male gametogenesis remains largely unknown. In this study, we found that WRKY 2 and WKRY 34 interact with VQ 20 both in vitro and in vivo . Further experiments displayed that the conserved VQ motif of VQ 20 is responsible for their physical interactions. The VQ 20 protein localizes in the nucleus and specifically expresses in pollens. Phenotypic analysis showed that WRKY 2, WRKY 34 and VQ 20 are crucial for pollen development and function. Mutations of WRKY 2 , WRKY 34 and VQ 20 simultaneously resulted in male sterility, with defects in pollen development, germination and tube growth. Further investigation revealed that VQ 20 affects the transcriptional functions of its interacting WRKY partners. Complementation evidence supported that the VQ motif of VQ 20 is essential for pollen development, as a mutant form of VQ 20 in which LVQK residues in the VQ motif were replaced by EDLE did not rescue the phenotype of the w2‐1 w34‐1 vq20‐1 triple‐mutant plants. Further expression analysis indicated that WRKY 2, WRKY 34 and VQ 20 co‐modulate multiple genes involved in pollen development, germination and tube growth. Taken together, our study provides evidence that VQ 20 acts as a key partner of WRKY 2 and WKRY 34 in plant male gametogenesis.