Bacterial Blight Resistance And T-DNA Flanking Sequence Analysis Of Xa23-Transgenic Rice

Rice Bacterial blight (BB) is one of the most serious bacterial disease in rice production. It is a vascular disease, chemical control is poor. Breeding disease-resistant varieties and promotion is one of the most important way to prevent this disease. Currently known bacterial blight resistance gene have as many as 31, However, breeding was not much use, mainly Xa4 gene (indica rice varieties) Xa3 gene (rice varieties), the two resistant genes in partly rice areas have lost resistance, the Xa21 gene which is discovered in Africa long wild rice (Oryzae longist aminata) is a dominant resistance gene, but many of rice areas at home and abroad has found that the loss of resistance. Xa23 gene is a new gene, which was discovered from the wild rice, that was known the most widely spectrum for bacterial blight resistance, with the characteristics of full dominance and high resistance to the whole growth period, these characteristics has broad application prospect for the improvement to hybrid rice in China.With vaccination, PCR identification and Southern blot analysis,this study analyzed the stability and transgenic model of the contemporary and future generations (from T₀ generation to T₂ generation) of the transgenic rice, and obtained two purely genetic lines, and stability resistant germplasm resources of the transgenic Xa23 gene. We select respectively a sample from the four T₁ groups, and analyzed its flanking sequence by PCR-Walking to analyze the position effect of T-DNA insertion:Key results are as follows:1. Throuth the vaccination of contemporary groups of the transgenic rice, we retained different degrees of resistance transgenic material. The vaccination identification results of future generations showed that future generation have ability of genetic stability and the stability of expression to bacterial blignt resistance.2. Throuth the vaccination of contemporary groups of the transgenic rice,The results showed that the receptor plant acquired resistance and also can be detected hygromycin resistance. Southern blot analysis result showed that: contemporary and future generations of transgenic plants has the same hybrid band in its size and type, From the molecular level,It proved that the foreign genes can stabily genetic and expression in the rice genome. 3. With PCR-Walking, The T-DNA flanking sequence analysis results of four single copy plants from T₁ groups showed only a single plant from 2006 groups obtained the expected results, sequencing results showed that T-DNA insert rice genome No.12 Chromosome, T-DNA being inserted into the rice genome specific sites are: the 9311 rice genome 11284676 bp, the site locate between the intron of the ORF box OS1290291600 and OS1290291800, non-coding sequence. ORF box OS1290291600 and OS1290291800 encode tRNA.Through this research, it retained two purely genetic lines which include Xa23 gene, and clearly assure the T-DNA insertion of the rice genome specific location, these rusults provide the theoretical basis and germplasm resources for the Xa23 gene cloning and the use.