GhSOS1, a plasma membrane Na+/H+ antiporter gene from upland cotton, enhances salt tolerance in transgenic Arabidopsis thaliana

Upland cotton (Gossypium hirsutum L.), an important source of natural fiber, can tolerate relatively high salinity and drought stresses. In the present study, a plasma membrane Na+/H+ antiporter gene, GhSOS1, was cloned from a salt-tolerant genotype of G. hirsutum, Zhong 9807. The expression level of GhSOS1 in cotton roots was significantly upregulated in the presence of high concentrations of NaCl (200 mM), while its transcript abundance was increased when exposed to low temperature and drought stresses. Localization analysis using onion epidermal cells showed that the GhSOS1 protein was localized to the plasma membrane. The overexpression of GhSOS1 in Arabidopsis enhanced tolerance to salt stress, as indicated by a lower MDA content and decreased Na+/K+ ratio in transgenic plants. Moreover, the transcript levels of stress-related genes were significantly higher in GhSOS1 overexpression lines than in wild-type plants under salt treatment. Hence, GhSOS1 may be a potential target gene for enhancing salt tolerance in transgenic plants.