Development of SSR molecular markers for bacterial leaf streak resistance gene bls2 in rice (Oryza sativa L.)

【Objective】SSR markers closely linked to the resistance gene bls2 against bacterial leaf streak(BLS) were developed in order to provide technical support for the cultivation of BLS-resistant rice varieties by molecular marker-assisted selection(MAS).【Method】Based on the preliminary mapping of the resistance gene bls2, the SSR markers were designed in the interval of markers SL03 and SL04 and those primers with polymorphism between parents were screened to detect the individual genotype in BC₃F₂ population which was bred by common wild rice DY19 and indica rice 9311 as parents. Combined with the measurement results of the length of lesions caused by BLS, bls2 gene was fine mapped by software MapQTL 5.0, therefore the SSR markers closely linked to bls2 were determined and the selection effects of unilateral and bilateral markers were compared.【Result】It was found that the segregation of resistant and susceptible plants in BC₃F₃ population accorded with Mendelian monogene segregation of 1:3 by resistance identification to BLS in field. Eleven pairs of polymorphic markers between parents were screened to detect the genotypes of 244 individual plants in BC₃F₂ population, then the location of the resistance gene bls2 was mapped to the physical distance of 240 kb between markers RM13592-RM13599 on chromosome 2 combined with individual phenotype identification. Both markers RM13592 and RM13599 segregated at ratio of 1:2:1, which was completely agreement with monogene searegation law. In BC₃F₃ population, the use of unilateral marker RM13592 or RM13599 and the simultaneous use of bilateral markers were effective for the selection of susceptible and resistant plants. The MAS selection accuracies of unilateral markers RM13592 and RM13599 were 92.62% and 93.44% respectively, while the selection accuracy of bilateral markers was 93.44%.【Conclusion】RM13592 and RM13599 are closely linked to the resistance gene bls2 and have the characteristics of easy PCR amplification, easy identification and high accuracy, so they can be used as effective markers of MAS in breeding rice variety against BLS.