Study On Improvement Of Salt Tolerance By Transformation With Transcription Factor DREB In Wheat (Triticum Aestivum L.)

The salt stress is an important factor influencing production of wheat. The soil of some areas of our country salinizes seriously, so it is very significance to improve the wheat's salt tolerance by genetic engineering.The plasmid expression vector including DREB1A gene and bar gene was constructed. DREB1A (dehydration responsive element binding) is a transcription factor and introduced the expression of a series of stress-related genes. The bar gene encodes the resistance to herbicide and is used to select the transgenic plants.The DREB1A gene in the plasmid pAHC25-DREB1A was transferred into 932 calli induced by young spikes of wheat cultivar H6756 by microprojectile bombardment, and 205 plantiets were regenerated through screening on the medium containing Basta. According to the resistance test by daubing with 100mg/l Basta solution on the seedling leaves 89 transformed plants survived. By PCR amplification and Southern Blotting, 50 plants were identified to be the transgenic ones containing the target gene of transcription factor DREB1A gene, and the frequency of transformation reached 6.72%. Seeds from 31 transgenic plants were planted and selected for molecular characterization (PCR and Southern Blotting), it was found that progeny of 20 plants integrated DREB1A gene. The results showed that the DREB1A gene can be transmitted to the next generation relatively steadly. Further molecular characterization in Ta generation showed that DREB1A gene wasn't monitored in progeny of 4 TI plants, while it existed in all progeny of 4 T1 plants and segregated in different rates in progny of other T1 plants, which comfirmed that DREB1A gene can be dominantly inherited. Germination tests in 2.0% NaCl concentration showed that the salt tolerance of transgenic wheat was higher than the controls. In addition, the glycoproteins layer at the cell surface of transgenic wheat became more compact in the condition of 2.0% NaCI salt stress, while those of control plants were destroyed or dropped.The DREB1A gene in the plasmid pC3300IS-DREB1A was also transferred into the wheat cultivar H6756 by Agrobacterium-mediated transformation. The stem apical meristem of wheat seedling was cultured together with Agrobacterium, and 247 seedlings were obtained. While 66 plants survived by selection with 100mg/l Basta. Monitoring the target gene amplified by PCR, 30 plants integrated the DREB1A gene, the frequency of transformation reached 12.1%The transformation systems of microprojectile bombardment and Agrobacterium-mediated were perfected and used to produce wheat lines with salt tolerance in this study. Transgenic wheat lines with DREB1A gene were obtained succesfully in an improved transformation efficiency.