Enhanced salinity stress tolerance in transgenic chilli pepper (Capsicum annuum L.) plants overexpressing the wheat antiporter (TaNHX2) gene

Abstract

Transgenic chilli pepper (Capsicum annuum L.) plants tolerant to salinity stress were produced by introducing the wheat Na+/H+ antiporter gene (TaNHX2) via Agrobacterium-mediated transformation. Cotyledonary explants were infected with Agrobacterium tumefaciens strain LBA4404 harboring a binary vector pBin438 that contains a wheat antiporter (TaNHX2) gene driven by the double CaMV 35S promoter and NPT II gene as a selectable marker. PCR and semiquantitative RT-PCR analysis confirmed that the TaNHX2 gene had been integrated and expressed in the T1 generation of transgenic pepper plants as compared to the non-transformed plants. Southern blot analysis further verified the integration and presence of TaNHX2 gene in the genome of chilli pepper plants. Biochemical assays of these transgenic plants revealed enhanced levels of proline, chlorophyll, superoxide dismutase, ascorbate peroxidase, relative water content, and reduced levels of hydrogen peroxide (H2O2), malondialdehyde compared to wild-type plants under salt stress conditions. The present investigation clearly showed that overexpression of the TaNHX2 gene enhanced salt stress tolerance in transgenic chilli pepper plants.