Isolation and Semi Quantitative PCR of Na⁺/H⁺ Antiporter (SOS1 and NHX) Genes under Salinity Stress in Kochia scoparia

Background: Kochia scoparia is a dicotyledonous annual herb and belongs to the Amaranthaceae family. Genetic diversity and resistance to drought stress of this plant has made it widely scattered in different regions which contains highly genetic diversity and great potential as fodder and can grow on salty, drought affected areas. Since the soil salinity has become widely spread, environmental concern has sparked so many debates. An important limiting factor in agricultural production worldwide is the sensitivity of most of the crop to salinity caused by high concentration of salts soil. Plants use three different strategies to prevent and adapt to high Na⁺ concentrations. Antiporters are important category of genes that play a pivotal role in ion homeostasis in plants. Na⁺/H⁺ antiporters (NHX1 and SOS1) are located in tonoplasts and reduce cytosolic Na⁺ concentration by pumping in the vacuole whereas SOS1 is localized at the plasma membrane and extrudes Na⁺ in apoplasts.

Results: Coding sequence of plasma membrane Na⁺/H⁺ antiporter (SOS1) and vacuole membrane Na⁺/H⁺ antiporter (NHX) in Kochia scoparia were isolated using conserved sequences of SOS1 and NHX. Also, expression profile under salinity stress was studied in this study. The amino acid sequences (aa) of the isolated region of K.SSOS1 and K.SNHX showed the maximum identity up to 84% and 90% to its orthologous in salicornia brachiate and suede maritime, respectively. The results of semi-quantitative RT-PCR revealed that salinization has affected positively on SOS1 transcription level. The expression of K.SSOS1 and K.SNHX in leaves and roots of Kochia scoparia were progressively increased under all salinity levels compared to control.

Conclusion: The results suggest that K.SSOS1 and K.SNHX play an essential role in salt tolerance of K.scoparia and they can be useful to improve salt tolerance in other crops.