Woodland strawberry WRKY71 acts as a promoter of flowering via a transcriptional regulatory cascade

Abstract

The WRKY proteins are a large family of transcription factors that play important roles in stress responses and plant development. However, the roles of most WRKYs in strawberry are not well known. In this study, <i>FvWRKY71</i> was isolated from the woodland strawberry 'Ruegen'. <i>FvWRKY71</i> was highly expressed in the shoot apex and red fruit. Subcellular localization analysis showed that FvWRKY71 was located in the nucleus. Transactivation analysis showed that FvWRKY71 presented transcriptional activation activity in yeast. Overexpression of <i>FvWRKY71</i> in Arabidopsis and woodland strawberry revealed early flowering in the transgenic plants compared with the wild-type control. Gene expression analysis indicated that the transcript levels of the flowering time and development integrator genes <i>AP1</i>, <i>LFY</i>, <i>FT</i>, <i>AGL42</i>, <i>FUL</i>, <i>FPF1</i>, <i>SEP1</i>, <i>SEP2</i>, and <i>SEP3</i> were increased in <i>FvWRKY71-</i>overexpressing Arabidopsis and strawberry plants compared with the wild-type controls, which may result in accelerated flowering in transgenic plants. Furthermore, FvWRKY71 was proven to directly bind to the W-boxes (TTGACT/C) of the <i>FvFUL</i>, <i>FvSEP1</i>, <i>FvAGL42</i>, <i>FvLFY</i>, and <i>FvFPF1</i> promoters in vitro and in vivo. Taken together, our results reveal a transcriptional regulatory cascade of FvWRKY71 involved in promoting flowering in woodland strawberry.