Cloning And Expression Analysis Of CcSOS1 Gene From Chrysanthemum Crassum

Excess Na+ in the soil will seriously affect the growth and development of plant. The plasma membrane Na+/H+ antiporter can catalyze Na+ efflux, is one of the most important adjustable mechanisms of plants to withstand salt stress, and it plays a crucial role in salt tolerance of plants. Chrysanthemum crassum (Kitam.) Kitam., originates in the coastal areas of Japan, is an excellent species because of its high salinity tolerance, but until now its salt tolerance still lacks in-depth research.In this report, a full length cDNA of plasma membrane Na+/H+ antiporter gene named CcSOSl was isolated from Chrysanthemum crassum by means of RT-PCR and RACE, the degenerate primers used in this experiment were designed based on the conservative sequences of other plasma membrane Na+/H+ antiporters promulgated in GenBank. The full length cDNA of CcSOSl was 3752bp, and the ORF was 3438bp which was predicted to encode a polypeptide of 1145 amino acid residues. The hydrophobicity and transmembrane domains analysis indicated that the N-terminal part of CcSOSl was hydrophobicity and there were 12 transmembrane domains, while the C-terminal part of CcSOSl was a long hydrophilic tail existed in cytoplasm. CcSOS1 had a highly similar sequence with VvSOS1, S1SOS1 and PeSOS1, came from Vitis vinifera, Solanum lycopersicum and Populus euphratica, and the identities were 79.11%,77.68% and 76.04% respectively. Phylogenetic tree analysis showed that CcSOSl belonged to plasma membrane Na+/H+ antiporter, the result of subcellular localization showed that CcSOSl was localized in the plasma membrane of cells.Quantitative real-time PCR (qRT-PCR) showed that CcSOS1 expressed in roots and leafs under the natural condition, the expression level in leafs was a little higher than that in roots, means that, CcSOS1 gene was constitutive expressed and had no obvious organic specificity. Under the salt stress, the expression level of CcSOSl in roots increased sharply and reached to the peak in 1h after treatment, it was about 11 times higher than that at Oh; In addition, the drought, low temperature and ABA could affected the expression of CcSOSl in varying degrees, but the patterns of them were different. Besides, the exogenous Ca2+ could improve the expression of CcSOSl in roots.A plant expression vector for CcSOSl gene pCAMBIA-1301-220-CcSOS1 was constructed by inserting new resitriction site to the vector, and it was important to plant transformation and in-depth study of the function of CcSOSl gene.