The proper timing of the floral transition is critical for reproductive success, and plants have evolved sophisticated and elaborate regulatory mechanisms to coordinately control flowering so that it occurs at the optimal time.  

Despite the evidence for WRKY transcription factor involvement in flowering time regulation described above, the molecular mechanisms underlying the effects of WRKY transcription factors during floral initiation are still largely unknown. 

In a new study published in Plant Physiology, Prof. YU Diqiu and his team from Xishuangbanna Tropical Botanical Garden (XTBG) of the Chinese Academy of Sciences newly identified Arabidopsis thaliana WRKY DNA binding protein75 (WRKY75) as a positive regulator of flowering initiation. 

The researchers used a molecular genetic approach to investigate the role of WRKY75 in flowering time regulation.

The results demonstrated that altered expression of the WRKY75 gene affects floral initiation. 

Further investigation indicated that WRKY75 acts as a transcriptional activator to transmit gibberellic acid (GA)-mediated flowering signals by directly binding to downstream target sequences such as FLOWERING LOCUS T (FT). 

Moreover, investigation of the associated mechanisms revealed that degradation of transcriptional repressors (DELLAs) physically interacted with WRKY75 and repressed its activation ability. 

The study showed that WRKY75 functions as a new component of the GA-mediated signaling pathway to modulate the onset and progression of floral initiation. It provides evidence that WRKY75 functions as a positive regulator of flowering in Arabidopsis.