VvWRKY22 transcription factor interacts with VvSnRK1.1/VvSnRK1.2 and regulates sugar accumulation in grape

WRKY transcription factors are one of the largest transcriptional regulator families, involved in various signaling networks in plants. However, only limited functional exploration of the sugar signaling of Vitis vinifera WRKY22 transcription factor (VvWRKY22) has been conducted. In this study, the roles played by VvWRKY22 in sugar accumulation in grapes were investigated. VvWRKY22 was co-expressed with 16 sugar-related genes, and the expression of VvWRKY22 in grape suspension cells was inhibited by sucrose, and induced by fructose and abscisic acid (ABA). Results showed that over-expression of VvWRKY22 decreased the sucrose, glucose and fructose content, and regulated the expression levels of sugar and ABA-related genes. Moreover, it was found that VvWRKY22 interacted with VvSnRK1.1 or VvSnRK1.2 proteins (Sucrose non-fermenting-1-related protein kinase 1), which are important kinases related to sugar metabolism. These results, thus, provide new genetic evidences to support the view that VvWRKY22 functions in regulating sugar metabolism in grapes.