| Rice (Oryza. sativa) is one of the most important food crops in the world. It provides food and sources of protein to more than half of the world's population and occupies a pivotal position in food production. Bacterial blight (BB), caused by Xanthomonas oryzae pv. oryzae (Xoo), is one of the most serious plant diseases of rice world wild. The using of host resistance, selection and utilization of varieties carrying R genes are proved one of the most economical, effective and environment-friendly strategies for BB management.A new rice germplasm C4064 for BB resistance was found, which performed especially resistance during evaluation of wild rice and their transfer breeding lines for bacterial blight resistance. In this study, we carried out systematic study on it, the results are as follows:1. Identification of the new gene: Through comparison of resistance spectrum with all known bacterial blight resistance genes and genetic analysis, the rice germplasm C4064 was proved harbored a new bacterial blight resistant gene, designated as Xa32(t).2. Molecular mapping of the new gene Xa32(t): To molecularly map Xa32(t) gene, Bulked Segregant Analysis (BSA) was adopted to survey SSR and EST molecular markers. Nine molecular markers RM27256, RM27274, RM2064, RM224, ZCK24, RM27296, Sub11, RM6293 and RM5926 were found to show polymorphism between R-pool and S-pool. By analyzing the F2 populations and one F3 population, the gene Xa32(t) was mapped on the long arm of rice chromosome 11. The new BB-resistance gene Xa32(t) was mapped within a length of 2.0cM on the long arm of rice chromosome 11, with a physical distance about 1240Kb. At the same time 3 CAPS markers were found which showed polymorphism between R-pool and S-pool.3. Near-isogenic line construction for Xa32(t): Using cross and backcross means, resistance gene Xa32(t) was introgressed into the susceptible variety Jingang 30 (JG30), the selective breeding of near-isogenic lines have been obtained BC4F1 generation. |
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