Molecular Cloning And Expression Analysis Of Plasma Membrane Na+/H+Antiporter Gene From Halophyte Suaeda Salsa

Salinity is one of the major abiotic stress factors that adversely effect the growth and yield of crop plant. The excessive sodium ions in soil cause ions toxicity, osmotic stresses and induced secondary stress, even lead the plants to death. One of the effective strategies that enable plants to resist salt stress is pumping out Na+into extracellular, and through long-distance transport it into the leaf and finally storaged in the vacuolar. This process can avert the deleterious effects of Na+in the cytosol and maintain osmotic balance by using Na+accumulated in the vacuole to drive water into the cells, and improve salt tolerance of plants. Therefore, it is important meaning for genetic improvement of salt tolerance of the crops and herbages to isolate and characterize the plasma membrane Na+/H+antiporter from halophytes lived in extremely saline environment.In this study, the plasma membrane Na+/H+antiporter gene, SsSOS1was cloned from the halophytes Suaeda salsa, and expressionof SsSOS1was analyzed using ACTIN as internal control. The main resultswere as following:1. Degenerate primers were designed based on the conserved sequences of the plasma membrane Na+/H+antiporter genes from other plants. A novel plasma membrane Na+/H+antiporter gene was isolated from Suaeda salsa using RT-PCR and RACE, and named as SsSOS1. The cDNA is3826bp in length including an open reading frame (ORF) of3507bp, a5’ untranslated region (5’URT) of86bp and a3’untranslated region (3’URT) of233bp with a ploy (A) tail. The SsSOS1cDNA encodes a protein of1169amino acids with a deduced molecularmass of129KDa and a p1of6.14. The SsSOS1protein shares97%,78%,69%and64%homology with the four reported other SOS1, namely SjSOS1(AB198179.1), McSOS1(AM746987.1), ZxSOS1(GU177864.1) and ThSOSl (EF207775.1) respectively. SsSOS1has eleven putative transmembrane (TM) domains.2. Semi-quantitative RT-PCR analysis results showed that in all treatments, the expression of SsSOS1is highest in the root, higher in the stem and lowest in the leaf. after NaCl (25-250 mM) or KC1(0.1-10mM) treatments, compared with controls, the expression of SsSOS1had no significant difference between root, stem and leaf; After150mmol·L-1NaCl treat Suaeda salsa for0-120h, the SsSOS1expression of root had no significant difference, the SsSOS1expression of stem had no significant difference in the first48h, but decreased after than, and this decrease stabled in96-120h, the SsSOS1expression of leaf had no significant difference in the first72h, but had a slowly increace after72h. This show that the SsSOS1expression in different time-course is adjusted by salt stress.