SbNAC2 enhances abiotic stress tolerance by upregulating ROS scavenging activities and inducing stress-response genes in sorghum

Major abiotic stresses such as drought and salinity affect the growth and yield of crops. NAC (NAM, ATAF1/2, and CUC2) is a plant-specific gene family that has been demonstrated to contribute to responses and adaption to abiotic stress in plants. The specific NAC transcription factors (TFs) that play important roles in the response to abiotic stress in sorghum are unknown. Here, we characterized a sorghum TF, SbNAC2, that can be strongly induced by abiotic stresses, including polyethylene glycol (PEG)-simulated dehydration stress treatment, salt treatment, and 4 °C chilling. Knockdown of SbNAC2 in sorghum seedlings by virus-induced gene silencing (VIGS) weakened the drought tolerance of plants. Heterologous overexpression of SbNAC2 in Arabidopsis and rice can induce plant antioxidant enzyme activity under abiotic stress conditions. Furthermore, SbNAC2 directly activates the expression of a stress responsive AP2/ERF type TF gene, SbAP37, by binding to the TTNCGTA motif of its promoter. These results indicate that SbNAC2 functions as a potentially important regulator in response to abiotic stresses and that it may possibly be used for molecular breeding to enhance crop yields under adverse environmental conditions.