Ectopic expression of a grape vine vacuolar NHX antiporter enhances transgenic potato plant tolerance to salinity

Salinity is a crucial environmental constraint that reduces plant productivity. However, plants activate different signaling pathways to overcome the abiotic stress. The NHX (Na+/H+ exchanger) antiporter corresponds to one of the antiporters involved in response to salinity. They are known to be responsible for the vacuole compartmentation of toxic Na+. In this report, a grapevine vacuolar antiporter (VvNHX1) cDNA was introduced into potato, response of transgenic plants to salinity was evaluated under in vitro and greenhouse culture conditions. The transgenic plants showed higher growth rate than wild type (WT) after the salinity treatment suggesting an improved tolerance both in vitro and under greenhouse culture conditions. In addition, a lower oxidative stress level was observed while a higher relative water and soluble sugar content were measured in transgenic plants compared to WT plants. Furthermore, in contrast to WT plants, the transgenic plants displayed an increase of leaf ion (K+, Mg2+) content and a decline in Na+ accumulation. The increase in the antioxidant enzyme activities in transgenic plants suggests that they can overcome oxidative stress resulting from salt treatment. The measurement of the tuber yield and the weight loss of plants sprinkled with 100 mM NaCl in the greenhouse showed a low negative effect on transgenic plants (12.5 and 40%) in comparison to WT (80%).