Mechanisms of Kale BoWRKY11-Mediated ABA Response and ROS Scavenging in Enhancing Plant Drought Tolerance

The objective of this study was to clone the BoWRKY11 gene of kale and explore its molecular mechanism of enhancing plant drought tolerance by scavenging reactive oxygen species and regulating downstream gene expression. Bioinformatics was used to analyze gene characteristics; subcellular localization and yeast one-hybrid validation were performed via Agrobacterium transformation. Tobacco overexpression and kale VIGS silencing lines were constructed. Combined with simulated drought and natural water-withholding treatments, physiological and biochemical assays, histochemical staining, and qPCR technology were comprehensively used to evaluate its function. BoWRKY11 belongs to Group II of the WRKY family. Its promoter is rich in ABA-responsive elements and is significantly induced by drought, high salt, and exogenous ABA. The protein localizes to the nucleus, possesses transcriptional activation activity, and specifically binds to W-box elements. Overexpression of this gene significantly increases the activities of antioxidant enzymes such as SOD and POD, reduces the contents of H2O2 and MDA as well as relative conductivity, decreases the accumulation of reactive oxygen species, and upregulates multiple downstream defense genes. VIGS silencing resulted in decreased plant water content, decreased stomatal conductance, and increased ion permeability, showing a typical drought-sensitive phenotype. BoWRKY11 is a positive regulator of the plant drought tolerance response, which significantly enhances plant drought tolerance by activating the antioxidant system and regulating the defense gene expression network.