Transformation Of Tomato With The BADH Gene From Atriplex Hortensis Improves Salt Tolerance

Glycinebetaine is an important compatible solute in response to salt,drought and other osmotic stresses in many organisms. It exists in cytoplasm as a non-toxic osmolyte and its concentration increases so as to maintain the osmotic balance of the cell when plants are stressed. At the same time,it acts as a low molecular weight chaperone to stabilize the structure of the protein and enzyme so that they can keep in functional conformation. Synthesis of glycinebetaine needs the catalysis of betaine aldehyde dehydrogenase (BADH) encoded by BADH gene that converts betaine aldehyde into glycinebetaine in some halotolerant plants. We transformed the BADH gene,which was cloned from Atriplex hortensis L. and controlled by double 35S promoters of cauliflower mosaic virus,into a salt sensitive tomato (Lycopersicon esculentum L. 'Bailichun') with Agrobacterium tumefaciens strain LBA4404 carrying a binary vector pBin438 via a leaf regeneration system. Fifteen kanamycin-resistant plants were obtained. PCR and Southern hybridization analysis demonstrated that the exogenous BADH gene had been integrated into the genome of six transformed tomato plants. There was one copy of exogenous BADH gene in three transgenic plants,two copies in two plants,and three copies;n one plant,respectively. Among the six transgenic plants,the BADH gene expressed in five plants at a level different from each other but higher than that of the w Id type. The relative electronic conductivity of the five transgenic plants were lowe;than the wild type at 90mmol/L,180mmol/L,270mmol/L NaCl stress,which led iio greater capability to maintain relative stable intracellular environment,and suggested that their salt tolerance was improved. The transgenic plants grew and fruited lormally under 90mmol/L NaCl stress. Transgenic progenies were obtained by strict self-pollination in controlled conditions and were used for progeny analysis. Te st of kanamycin tolerance of TI seedlings demonstrated that the tolerant and sensitive progenies fit a 3:1 segregation ratio. Salt tolerance evaluation of the progenies was performed in vitro and in soil-lesscondition. Germination ratio and growth status of the transgenic lines were improved significantly under salt stress. Transgenic seedlings showed higher levels of root production and hypocotyls showed higher differentiation ratio than wild type on NaCl-supplemented medium respectively. These results suggested a positive effect of the BADHg&iQ on salt tolerance of transgenic progenies.Ion stress is another toxic effect induced by salt stress. We transformed the BADH gene into an AtNHXl transgenic tomato (L. esculentum 'Moneymaker') in order to obtain double salt-tolerant related genes transgenic tomato. PCR and southern analysis demonstrated that BADH gene had been integrated into the genome of AtNHXl transgenic tomato. Molecular and physiological examinations of them are now in process.