Candidate Genotypes Screened From Chinese Soybean Elite Cultivars For Transformation

Soybean is a major source of plant for edible oil and protein, plays an important role in the human diet. In recent years, with planting area increase of genetically modified soybean, they are occupying more and more soybean market.Agrobacterium tumefaciens-mediated transformation of soybean is highly genotype-dependent. Since the elite soybean cultivars were transformed reluctantly, it limited to breed the new transgenic varieties. In our research, 13 elite soybean cultivars were used in the comparison of regeneration and infection efficiency during their transformation, as well as in the analysis of the relationship between rates of shoot inducing and shoot elongating among the cultivars. The results revealed that the regeneration ability and the transformation efficiency differentiate greatly among these cultivars, while no notable difference was observed after the infection of Agrobacterium tumefaciens. The elongation efficiency among the 13 cultivars demonstrated significant differences after the infection and the screening phases, which affected the efficiency of transformation as well. Four elite cultivars were selected according to their high transformation efficiency. Zhonghuang 42 and Zhonghuang 39 are suitable for cultivation in Huang-Huai-Hai rivers valley and other central region in China. Guixia no.3 is suitable for cultivation in the southern soybean area, but Jiangmodou no.1 is suitable for Chinese northeast. The highest efficiency of transformation for Zhonghuang 42 was 4.07%. These selected cultivars provided the ideal materials for soybean germplasm created by genetic transformation strategy.Now, selective marker gene is widely used in genetic transformation to screen positive transformed plants. There may be some potential risks, would cause a relatively large controversy. Due to the lack of key gene, the plant can not use phosphites. In this research, a screening system containing phosphite dehydrogenase(ptxD) gene and phosphites were used to screen soybean in Agrobacterium-mediated transformation. The results showed that the system worked in lower screening efficiency, and did worse in the distinguishing transgenic plants between positive and non-positive, so the screening system is not suitable for genetic transformation of soybean.