Overexpression of a Barley Aquaporin Gene, Confers Salt and Osmotic Stress Tolerance in Yeast and Plants.

We characterized an aquaporin gene from and investigated its physiological roles in heterologous expression systems, yeast and , under high salt and high osmotic stress conditions. In yeast, the expression of enhanced abiotic stress tolerance under high salt and high osmotic conditions. Arabidopsis plants overexpressing also showed better stress tolerance in germination and root growth under high salt and high osmotic stresses than the wild type (WT). overexpressing plants were able to survive and recover after a 3-week drought period unlike the control plants which wilted and died during stress treatment. Indeed, overexpression of caused higher retention of chlorophylls and water under salt and osmotic stresses than did control. We also observed lower accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA), an end-product of lipid peroxidation in overexpressing plants than in WT. These results suggest that overexpression brought about stress tolerance, at least in part, by reducing the secondary oxidative stress caused by salt and osmotic stresses. Consistent with these stress tolerant phenotypes, overexpressing Arabidopsis lines showed higher expression and activities of ROS scavenging enzymes such as catalase (CAT), superoxide dismutase (SOD), glutathione reductase (GR), and ascorbate peroxidase (APX) under salt and osmotic stresses than did WT. In addition, the proline biosynthesis genes, Δ and ( and ) were up-regulated in overexpressing plants under salt and osmotic stresses, which coincided with increased levels of the osmoprotectant proline. Together, these results suggested that overexpression enhanced stress tolerance to high salt and high osmotic stresses by increasing activities and/or expression of ROS scavenging enzymes and osmoprotectant biosynthetic genes.