CrWRKY57 and CrABF3 cooperatively activate to modulate drought tolerance and root development.

Drought is a major abiotic stress. WRKYs are one of the largest families of transcription factors (TFs) in plants. The effects of most WRKYs on developmental regulation and drought adaptation in remain largely unclear. cv. Sanhu hongju (Sanhu) is a drought-tolerant variety from Jiangxi Province, China. Here, we report a differentially expressed gene in drought-treated Sanhu leaves through transcriptome analysis. Its transcriptional expression could be induced by abscisic acid (ABA) treatment and water deficit. Overexpression of in lemon () and tobacco () confers enhanced drought tolerance, while RNA interference (RNAi)-mediated silencing in Sanhu increases dehydration susceptibility and reduces root volume. Moreover, virus-induced gene silencing-mediated knockdown of in Sanhu reduces primary root length and lateral root number by nearly 50% compared to the control. The results of yeast two-hybrid, co-immunoprecipitation assays and bimolecular fluorescence complementation demonstrate that CrWRKY57 interacts with CrABF3, a key TF in ABA signaling. Silencing , its homolog in lemon, also increases drought sensitivity and disrupts root system development. Together, CrWRKY57 and CrABF3 directly activate the promoter of the cell cycle gene by binding to W-box and ABRE elements, respectively. Furthermore, silencing in Sanhu also severely reduces primary root length and lateral root number. Collectively, our findings provide a new perspective of as a positive player in drought response and highlight the role of the CrWRKY57-CrABF- module in enhancing drought tolerance by modulating root development.