Overexpression of a Barley Aquaporin Gene,HvPIP2;5Confers Salt and Osmotic Stress Tolerance in Yeast and Plants.
We characterized an aquaporin geneHvPIP2;5fromHordeum vulgareand investigated its physiological roles in heterologous expression systems, yeast andArabidopsis, under high salt and high osmotic stress conditions. In yeast, the expression ofHvPIP2;5enhanced abiotic stress tolerance under high salt and high osmotic conditions. Arabidopsis plants overexpressingHvPIP2;5also showed better stress tolerance in germination and root growth under high salt and high osmotic stresses than the wild type (WT).HvPIP2;5overexpressing 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 ofHvPIP2;5caused 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 inHvPIP2;5overexpressing plants than in WT. These results suggest thatHvPIP2;5overexpression 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,HvPIP2;5overexpressing 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, Δ1-Pyrroline-5-Carboxylate Synthase 1and2(P5CS1andP5CS2) were up-regulated inHvPIP2;5overexpressing plants under salt and osmotic stresses, which coincided with increased levels of the osmoprotectant proline. Together, these results suggested thatHvPIP2;5overexpression enhanced stress tolerance to high salt and high osmotic stresses by increasing activities and/or expression of ROS scavenging enzymes and osmoprotectant biosynthetic genes.
Department of Life Science, Sogang University Seoul, Korea.
Hemasundar
H
Alavilli
Plant Molecular Biotechnology Laboratory, Department of Life Science and Bioinformatics, Assam University Silchar, India.
Jay Prakash
JP
Awasthi
Department of Agricultural Biotechnology, Orissa University of Agriculture and Technology Bhubaneswar, India.
Gyana R
GR
Rout
Department of Bioscience and Biotechnology, Indian Institute of Technology Guwahati, India.
Lingaraj
L
Sahoo
Department of Life Science, Sogang University Seoul, Korea.
Byeong-Ha
BH
Lee
Plant Molecular Biotechnology Laboratory, Department of Life Science and Bioinformatics, Assam University Silchar, India.
Sanjib Kumar
SK
Panda
Arabidopsis; HvPIP2;5; aquaporin; barley; overexpression; stress tolerance; yeast