Cloning and functional characterization of FtWRKY29, a low phosphorus stress-inducible transcription factor in Tartary buckwheat

The regulation of the expression of genes related to abiotic stress in plants is significantly influenced by the binding of the transcription factor (TF) WRKY to the W-box elements in their promoters. The findings of this study have confirmed that the ability of Tartary buckwheat (Fagopyrum tataricum Gaertn.) to tolerate phosphorus (P) deficiency is regulated by FtWRKY29, which is classified as a member of group II of the WRKY family. The roots predominantly exhibited an enhanced expression of FtWRKY29, which was significantly upregulated in response to low-P-induced stress. The W-box motif was bound to by FtWRKY29 which enhanced the transcription of genes and was localized to the nucleus. The overexpression of FtWRKY29 in Arabidopsis thaliana produced transgenic lines that exhibited phenotypes typical of diminished sensitivity to low-P-induced stress by promoting root growth, increasing P-uptake, and regulating the accumulation of anthocyanin. The low-P-responsive genes, PHT1;1, PHT1;4, and PHO1 were significantly up-regulated in these lines. In addition, the overexpression of FtWRKY29 restored the P-absorption ability of the wrky75 mutant to a certain extent. Moreover, the binding of FtWRKY29 to the promoter of PHT1;1 activated its expression in tobacco. It was also observed that FtWRKY29 interacts with AtMPK3, AtMPK6, FtMPK3, and FtMPK7. This study provides preliminary evidence that FtWRKY29 improved the tolerance of transgenic A. thaliana plants to low-P-induced stress and deepened the understanding of the regulatory mechanism behind the same in Tartary buckwheat.