CaNAC67, a stress-responsive NAC transcription factor-encoding gene from chickpea (Cicer arietinum), improves drought tolerance in transgenic Arabidopsis thaliana

Drought is recognized as a major factor limiting crop growth and productivity globally. While NAC transcription factors are known for enhancing plant tolerance against various abiotic stresses, including drought, the specific functions of stress response-related NACs from chickpea (Cicer arietinum) remain underexplored. Here, we expressed the CaNAC67 gene in Arabidopsis thaliana (CaNAC67 plants) using the drought-inducible RD29A promoter from Arabidopsis and evaluated the resulting changes under drought conditions. Our study revealed that CaNAC67 plants exhibited greater survival and biomass under drought than wild-type (WT) plants. We observed that CaNAC67 plants displayed limited water loss, accompanied by higher leaf relative water content, elevated leaf temperatures, and decreased cuticular permeability. Furthermore, CaNAC67 plants significantly attenuated drought-induced reactive oxygen species (ROS) accumulation, indicating reduced drought-triggered oxidative damage compared with WT plants. This reduction in ROS levels was associated with enhanced activities of superoxide dismutase, catalase, and ascorbate peroxidase and the increased expression levels of their corresponding gene(s), suggesting a robust antioxidative defense mechanism in CaNAC67 plants. Moreover, the elevation of reduced glutathione (GSH), the improved reduced GSH/oxidized GSH ratio, and the upregulation of GSH biosynthesis-related genes in CaNAC67 plants underscored the bolstered antioxidant defense essential for ROS detoxification. Additionally, CaNAC67 plants exhibited improved expression of several drought-responsive NAC-mediated marker genes examined, further contributing to their enhanced drought tolerance. Our study provided mechanistic insights, highlighting the positive regulatory role of CaNAC67 as a key gene in conferring plant drought tolerance, which suggests its potential application for developing transgenic chickpea lines with improved drought tolerance.