TaASR1, a transcription factor gene in wheat, confers drought stress tolerance in transgenic tobacco

Abstract

Abscisic acid (ABA)-, stress-, and ripening-induced (ASR) proteins are reported to be involved in abiotic stresses. However, it is not known whether ASR genes confer drought stress tolerance by utilizing the antioxidant system. The findings of this study demonstrated TaASR1 function in drought/osmotic stress tolerance. TaASR1 conferred drought/osmotic stress tolerance through regulating the expression of stress-, and defense-associated genes and enhancing the antioxidant system, thus preventing plants from oxidative damage. Abscisic acid (ABA)-, stress-, and ripening-induced (ASR) proteins are reported to be involved in abiotic stresses. However, it is not known whether ASR genes confer drought stress tolerance by utilizing the antioxidant system. In this study, a wheat ASR gene, TaASR1, was cloned and characterized. TaASR1 transcripts increased after treatments with PEG6000, ABA and H2O2. Overexpression of TaASR1 in tobacco resulted in increased drought/osmotic tolerance, which was demonstrated that transgenic lines had lesser malondialdehyde (MDA), ion leakage (IL) and reactive oxygen species (ROS), but higher relative water content (RWC) and superoxide dismutase (SOD) and catalase (CAT) activities than wild type (WT) under drought stress. Overexpression of TaASR1 in tobacco also enhanced the expression of ROS-related and stress-responsive genes under osmotic stress. In addition, transgenic lines exhibited improved tolerance to oxidative stress by retaining more effective antioxidant system. Finally, TaASR1 was localized in the cell nucleus and functioned as a transcriptional activator. Taken together, our results showed that TaASR1 functions as a positive factor under drought/osmotic stress, involved in the regulation of ROS homeostasis by activating antioxidant system and transcription of stress-associated genes. © 2013 John Wiley & Sons Ltd.