The eelgrass Zostera marina antiporter gene (ZmNa+/H+) confers salt stress tolerance to ornamental tobacco (Nicotiana alata)

Salinity stress is a main restricting factor for plants’ growth and development, resulting from climate change. The ornamental tobacco (Nicotiana alata) from the Solanaceae family is a bedding plant with attractive flowers suitable for semi-arid and arid lands. In order to obtain salt tolerance, the Na+/H+ antiporter gene was transferred from the halophyte eelgrass (Z. marina) grown in saltwater lake Urmia to N. alata. For gene transformation, leaf explants were immersed in liquid medium containing Agrobacterium tumefaciens containing the vacuolar gene ZmNHX1. The explants were subcultured on MS medium supplemented with 1 mg L-1 benzyl amino purine, 0.1 mg L−1 naphthalene acetic acid, 200 mg L-1 cefotaxime and 10 mg L-1 kanamycin. After regeneration, salinity stress was applied by 0, 210, 230 and 240 mM NaCl in a completely randomized design with three replications. For the first time, vacuolar Na+/H+ antiporter gene ZmNHX1 was successfully transferred to ornamental tobacco. Compared to the wild type plants, the transgenic plants showed higher content of leaf chlorophyll, leaf carotenoid, fresh weight and dry weight of the whole plant, leaf proline content and leaf catalase activity. After salinity stress, the T revealed greater chlorophyll, carotenoid, anthocyanin, K+: Na+ ratio, fresh weight, dry weight, proline amount, catalase and ascorbate peroxidase activity. The T also demonstrated a lower decline in relative water content and a lesser increase of leaves electrolyte leakage, compared to the WT. The stable expression of ZmNHX1 obtained from eelgrass confer salinity stress tolerance in ornamental tobacco providing a new window for cultivation of this species in areas exposed to salinity stress and the resulting transgenic ornamental tobacco is suggested for garden flower cultivation in areas exposed to salinity stress.