The Transcription Factor BoNAC02 Enhances the Drought Resistance of Kale through an ABA-Dependent Pathway

Members of the NAC (NAM, ATAF1/2, CUC1/2) transcription factor (TFs) family play a crucial role in Brassica oleracea var. acephala growth regulation, developmental processes, and responses to abiotic stress. However, few studies have examined the roles of NAC proteins in the drought resistance of kale. Here, the NAC TF BoNAC02 was identified. It was strongly induced by drought and abscisic acid (ABA) and localized to the nucleus; it also transcriptionally activates the expression of other genes. The RNAi-induced silencing of BoNAC02 significantly weakened the drought stress tolerance of plants, and overexpression of BoNAC02 enhanced plant drought tolerance. Specifically, ABA mediated the regulation of drought tolerance via BoNAC02. In the expression analysis of drought resistance-related genes, significant changes were observed in the expression of genes related to ABA signaling and oxidase metabolism in BoNAC02-silenced plants. This result strongly suggested that BoNAC02 positively regulates ABA signaling and the drought response. Our findings provide new insights into the role of TFs, especially BoNAC02, in the stress resistance of plants; our results also have implications for the approaches to enhance the drought resistance of kale plants.