Abstract
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.
Highlights
Soil salinity is one of the major threats to agricultural productivity because it disturbs intracellular ion homeostasis and reduces metabolic activities in plants [1]
GhSOS1 was localized to the plasma membrane
The transgenic plants displayed a significantly lower Na+/K+ ratio than the wild-type plants under salt stress (Fig 7). These results indicated that the overexpression of GhSOS1 in Arabidopsis may promote the extrusion of Na+ and uptake of K+ to maintain a low Na+/K+ ratio in plant cells and improve the salt tolerance of transgenic plants
Summary
Soil salinity is one of the major threats to agricultural productivity because it disturbs intracellular ion homeostasis and reduces metabolic activities in plants [1]. Excess sodium ions (Na+) lead to water deficiency, membrane dysfunction, and ionic toxicity in plant cells [2]. It is essential for plants to maintain a low level of Na+ in the cytosol under salt stress. Plants have three mechanisms to prevent excessive Na+ accumulation in the cytosol: restricting influx, increasing efflux, and increasing Na+ sequestration into vacuoles [3]. Maintaining a low level of Na+ in the cytosol is largely mediated through transporters localized on the plasma membrane and tonoplasts [4]. In Arabidopsis, the plasma membrane Na+/H+ antiporter gene AtSOS1 was identified as one component of the Salt Overly Sensitive (SOS) signal transduction pathway [5].
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