Wheat WRKY24-1D, interacts with TaERFL1a, regualtes DHAR-mediated ASA-GSH biosynthesis to enhance drought tolerance in wheat

Abstract

Drought is a major environmental factor to limit wheat yield and quality. WRKY transcription factors play crucial roles in abiotic stresses, including drought stress. However, the regulatory mechanisms of WRKYs in wheat drought stress tolerance are largely unknown. In this study, we found a WRKY transcription factors TaWRKY24, which identified and screened between drought stress yeast library and drought-induced gene TaERFL1a, and the other yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) found that TaERFL1a was interacted with TaWRKY24-1D, which was more induced than TaWRKY24-1A under drought stress. Moreover, the potential function of TaWRKY24 was examined by using BSMV-VIGS method. Results found that transiently silenced of TaWRKY24 in wheat resulted in enhanced sensitivity to drought stress by increasing the contents of malondialdehyde (MDA) and hydrogen peroxide (H2O2), decreasing the activities of ascorbate peroxidase (APX), superoxide dismutase (SOD), or catalase (CAT), and contents of ascorbate (ASA) and glutathione (GSH), and inhibiting the biomass and relative water content. qPCR showed that the expression levels of ASA-GSH-related genes were also significantly inhibited in TaWRKY24-silenced wheat plants. Among these genes, dehydroascorbate reductase (DHAR) had a lowest expression than other ASA-GSH-related genes, indicating that it expression may be mainly regulate by TaWRKY24. In addition, yeast one-hybrid (Y1H), luciferase complementation imaging (LCI), and luciferase (LUC) assays showed that TaWRKY24 had higher activity to bound the promoter of DHAR than TaERFL1a, suggesting that TaWRKY24 positively regulated the expression levels of DHAR and interacted with TaERFL1a to involve in wheat drought tolerance. Therefore, these results providing a theoretical basis for the molecular regulatory mechanisms of TaWRKY24 in wheat drought resistance, and contributing to the potential candidate genes for breeding the drought resistance wheat varieties.