Overexpression of Arachis hypogaea NAC3 in tobacco enhances dehydration and drought tolerance by increasing superoxide scavenging.

Drought stress can severely affect plant growth and substantially diminish crop yields. We previously isolated Arachis hypogaea NAC3 (AhNAC3), a dehydration-induced NAM/ATAF/CUC (NAC) gene from peanut. In this study, to examine the role of AhNAC3 in stress tolerance, we constructed transgenic tobacco lines overexpressing AhNAC3. The transgenic plants showed hyper-resistance to dehydration and drought stresses and accumulated more proline and less superoxide anion (O2(-)) than wild type under dehydration and drought conditions. Moreover, the transgenic plants showed upregulation of four functional genes, superoxide dismutase (SOD), pyrroline-5-carboxylate synthetase (P5SC), late embryogenic abundant proteins (LEA), and early response to drought 10 (ERD10C). Protein localization and transactivation analysis suggested that AhNAC3 activates its specific targets in the nucleus. These results suggest that AhNAC3 is a dehydration-induced transcription factor that improves water stress tolerance by increasing superoxide scavenging and promoting the accumulation of various protective molecules.