Overexpression of Arabidopsis thaliana Na+/H+ antiporter gene enhanced salt resistance in transgenic poplar (Populus × euramericana ‘Neva’)

Salinity is a major abiotic stress factor limiting plant growth and productivity. One possible method to enhance plant salt-resistance is to compartmentalize sodium ions away from the cytosol. In the present work, a vacuolar Na+/H+ antiporter gene AtNHX1 from Arabidopsis thaliana, was transferred into Populus × euramericana ‘Neva’ by Agrobacterium tumefaciens in order to enhance poplar salt-resistance. The results showed that the transgenic poplar were more resistant to NaCl than the wild-type (WT) in greenhouse condition. Compared with the WT, plant growth and photosynthetic capacity of the transgenic plants were enhanced, and the transgenic plants accumulated more Na+ and K+ in roots and leaves under the same NaCl condition, whereas malondialdehyde and relative electrical conductivity were lower. All of these properties of the transgenic poplar were likely to be a consequence of the overexpression of AtNHX1 caused Na+ sequestration in the vacuoles and improved K+ absorption, thus reducing their toxic effects. These results indicated overexpression of the AtNHX1 enhanced salt-resistance of poplar, and AtNHX1 played an important role in the compartmentation of Na+ into the vacuoles. Therefore, this study provides an effective way for improving salt resistance in trees.