Studies On Rice OsDREB2.2 Gene Transformation Of Wheat Via The Agrobacterium-mediated Floral Dip Method

Abiotic stresses such as salt,drought,cold and freezing could cause severe damages on growth and development of plants, which are also the direct reasons of yield loss of crops. In plants,the expression of many genes were regulated at transcriptional level,and mostly it’s realized through cis- and trans-acting elements. The adverse condition induced transcription factors are one kind of proteins that can regulate transcriptions of a series of downstream resistance genes through their interactions with cis-elements or related proteins, which improved the integrated resistance of the plants. The plant AP2 family DREB group of transcription factors are the hot spot for the molecular breeding of transgenic tolerant plants in recent years. These genes have great significance for improving the integrated stress resistances of crops.Wheat is one of the most important stable crops in the world, and the breeding of new varieties is still depended on sexual crossbreeding by now. Some gratifying results have been obtained in recent years, however, feasible wheat transgenic technique has been advancing more slowly than that of other gramineous crops, including maize and rice. In the current, modern genetic engineering technology is a new way to wheat varieties breeding. It has many advantages, such as breaking the reproductive isolation, making different genetic exchange between species available, creating conditions for widening plant gene pool, making up the lack of conventional hybrid breeding, accelerating the development of crop genetic breeding.In this study, the young spikes of wheat varieties‘zhoumai16’and‘jimai38’planted in the greenhouse or in the field were used for transforming the rice OsDREB2.2 gene. The constructed eukaryotic expression vector is pBI121-OsDREB2.2, which contains CaMV35S promoter. The Agrobacterium used in this study were EHA105 and GV3101. The genome DNA was extracted from the first generation of transformed wheat, and the transformed OsDREB2.2 gene was tested by genome DNA PCR techniques. The results showed that we got T1 generation of OsDREB2.2 transgenic plants. The statistics of 1059 seeds produced from 106 stains showed that the average transformation efficiency has arrived 34.8%, and there was a discrepancy between different Agrobacterium and different wheat varieties. The same activity was detected in the second generation. Total RNA of 28 strains was extracted from the T2 generation of transformed wheat, and the OsDREB2.2 mRNA level was tested by RT-PCR. The electrophoresis showed that all the 28 strains have transcripts of OsDREB2.2 gene, of which 23 stains were in high level of transcription. The result showed that the transformed OsDREB2.2 gene had been successfully inherited to T2 generation, and makes transcription constantly. By 20% PEG and 250 mM NaCl treatment, we verified that the wheat plants with the overexpression of rice OsDREB2.2 gene significantly improved the drought resistance of seedlings, and some of the transgenic lines showed high salt tolerance. This study provides a new method suitable for wheat genetic transformation, especially for the the whole plant level transformation, it provides a fast, simple and efficient solution. The study also laid foundation for the promotion of genetically modified technology and the continuous of wheat variety improvement.The identification of copy number of transgenic gene copies is in progress.