Transformation of the salt-tolerant gene of Avicennia marina into tobacco plants and cultivation of salt-tolerant lines

Salt-tolerant gene, CSRGI, which was isolated from a kind of salt-tolerant mangroves, Avicennin marina, constructed the transgenic plasmid, pGAM189/CSRG1. CSRGI, GUS, Km(r) and Hyg(r) could be transferred into tobacco genome by the ameliorated leaf discs method of agro-bacterium -mediate transformation. Thirteen stable resistant lines were obtained when fifty transgenic explants were selected through 50 mg/L hygromycin and 150 mg/L, kanamycin. Assessments of PCR amplification, Southern blot analysis and GUS histochemical staining showed that CSRGI has been integrated into the genome of the eleven transgenic lines (frequency of transformation was 22%). Northern bolt analysis revealed that CSRGI had expressed in transgenic lines. The assessments of salt-tolerant ability and photosynthetic rates indicated that the survival rate of the transgenic lines is 80%-90% and the transgenic lines could increase by 30%-40% in plant height, even when they were cultivated in MS medium containing 2% NaCl and the total seawater (salinity 24). It is supposed that the special physiologic metabolic pathway formed by the products of CSRGI can really endow the tobacco plants with the high salt-tolerant ability, not only to Na+ stress, but also to the comprehensive stress of various tons.