Cyanobacteria Of Na ~ + / H ~ + Antiporter Gene Genetic Transformation Research

High salinity can disturb the ionic balance and cause the osmotic stress, It has become one of the major abiotic stresses which constraints crop plant growth, and reduces productivity.The SynNhap gene encoded one sort of membrane Na⁺/H⁺ antiporters, is cloned from the Synechocystis pcc6803. Its open reading frame is 1581bp, having a peptide of 527 amino acids, and it played an important role in salt tolerance. The SynNhap gene was transferred into tomato and alfalfa by agrobacterium tumefacience-mediated transformation. At the same time, the salt tolerance of F₁ generation transgenic tobacco was determined according to physiological function and enzymatic activity. The primary results were as follows:(1)The tolerance of F₁ generation transgenic tobacco to salt stress. The seed germination, survival rate, chlorophyll content, Na⁺ content and the salt tolerant character of F₁ generation transgenic tobacco were determined under different NaCl concentrations The results demonstrated that transgenic tobacco's seed germination, survival rate and chlorophyll content were higher than that of control tobacco; Na⁺ content to the contrary. At the same time transgenic tobacco could normally grow under the treatment of 200mM NaCl, while the growth of control tobacco was seriously inhibited.(2) Determination of activity in catalase (CAT) ,superoxide dismutase (SOD), peroxidase (POD), malondiadehyde (MDA) concentration and plasma membrane permeability in the F₁ generation transgenic tobacco. The results showed that the activity of SOD,POD and CAT in the transgenic tobacco was first increased and then decreased, and in generally, the activity of above three enzymes in transgenic tobacco was higher than control tobacco; plasma membrane permeability and MDA concentration were increasing gradually, but the increasing extent of transgenic tobacco was lower than that of control tobacco with the increasing of NaCl concentration. The results indicated that the tolerant improvement of transgenic tobacco to salt stress may be accompanied to the enhancement of antioxidative capacity.(3) The genetic transformation of tomato. The SynNhap gene was transfrred into tomato by agrobacterium tumefacience-mediated transformation. Using cotyledon as explants, the transgenic tomatoes were obtained. The results of PCR determination showed that the SynNhap gene has been inserted into the chromosome of tomato.(4) The genetic transformation of alfalfa. Using cotyledon as explants to induce and differentiate callus, and a lots of resistent callus with green prominence were created, the completely differentiated transgenic alfalfa was not yet obtained.