Overexpression of ZjWRKY10, a Zoysia japonica WRKY transcription factor gene, accelerates leaf senescence and flowering in transgenic Arabidopsis

The WRKY transcription factors play an important role in plants’ stress response, leaf senescence, growth, and development. In this study, we cloned ZjWRKY10 from the leaf of Korean lawngrass (Zoysia japonica), a warm-season turf; the deduced protein sequence showed high homology with the TaWRKY10 protein of wheat. The ZjWRKY10 and TaWRKY10 genes belong to group IIc of the WRKY transcription factor family, which regulates tolerance to multiple abiotic stresses. The study’s results showed that ZjWRKY10 was slightly upregulated by cold, sodium chloride, and polyethylene glycol 6000 treatments; however, it was strongly activated by a dark treatment. When ZjWRKY10 was overexpressed in Arabidopsis thaliana after dark treatment, it resulted in earlier leaf senescence compared with wild-type plants. In addition, the transgenic plants overexpressing ZjWRKY10 showed early-flowering phenotypes when exposed to long-day conditions compared with the wild-type plants. When comparing the transgenic with the wild-type plants, the increased expression of the FLOWERING LOCUS T (FT) gene, vital in triggering flowering, supported the earlier flowering observed in the transgenic Arabidopsis plants. These results support that ZjWRKY10 may be involved in the regulation of leaf senescence and flowering.