Over-expression of a vacuolar Na+/H+ antiporter gene improves salt tolerance in an upland rice
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To develop a salt-tolerant upland rice cultivar (Oryza sativa L.), OsNHX1, a vacuolar-type Na+/H+ antiporter gene from rice was transferred into the genome of an upland rice cultivar (IRAT109), using an Agrobacterium-mediated method. Seven independent transgenic calli lines were identified by polymerase chain reaction (PCR) analysis. These 35S::OsNHX1 transgenic plants displayed a little accelerated growth during seedling stage but showed delayed flowering time and a slight growth retardation phenotype during late vegetative stage, suggesting that the OsNHX1 has a novel function in plant development. Northern and western blot analyses showed that the expression levels of OsNHX1 mRNA and protein in the leaves of three independent transgenic plant lines were significantly higher than in the leaves of wild type (WT) plants. T2 generation plants exhibited increased salt tolerance, showing delayed appearance and development of damage or death caused by salt stress, as well as improved recovery upon removal from this condition. Several physiological traits, such as increased Na+ content, and decreased osmotic potential in transgenic plants grown in high saline concentrations, further indicated that the transgenic plants had enhanced salt tolerance. Our results suggest the potential use of these transgenic plants for further agricultural applications in saline soil.
KeywordsOver-expression OsNHX1 Vacuolar Na+/H+ antiporter Salt tolerance Transgenic upland rice plants
We thank Dr. Fukada (Department of Plant Physiology, National institute of Agrobiological Resources, Japan) for kindly providing the vector: pOsNHX1, containing the OsNHX1 cDNA, as well as for supplying the OsNHX1 antibodies. This work was supported by grants from the National Basic Research Program of China (grant nos. 2006CB100100 and 2003CB114307) and from the National Science Foundation of China (grant nos. 30370129 and 30421002).
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