Marker Assisted Selection Of Bacterial Blight Resistance Genes Xa5、Xa7、Xa23

Bacterial blight (BB) is one of the most destructive bacterial diseases of rice in the world. A present, planting resistant cultivars is the most economic and effective measure for the control and prevention of BB. Therefore the effective resistance genes of BB and its marker-assisted selection have important significance in rice production. This paper mainly studied on the effective resistance genes to BB in Guangxi, the pathogenicity reaction of rice parents with pathogenic types IV of Xanthomonas oryzae pv. oryzae in Guangxi, the specific molecular markers and marker assisted selection of the effective resistance genes. Results of the research were as follows:The prevalence pathogenic types IV of Xanthomonas oryzae pv. oryzae was inoculated on72parental varieties which contained a set of single BB resistance gene lines (Near isogenic lines) to make clear the pathogenicity association of rice parents. The result showed that the resistant effect of genes xa5, Xa7and Xa23were distinguished, and the resistant parental varieties were scarce as the donor parents of effective genes xa5, Xa7, Xa23were eagerly needed to introduce to breeding for disease resistance in Guangxi;According to the sequence of recessive resistance gene xa5and its two different bases which contrasted with the dominant sequence, this study developed a STS function marker M-xa5for the specific identification of gene xa5based on PCR;PCR amplification of72rice parents DNA by M-xa5, M5, and M-Xa23were used to identify the specific of those molecular markers to their corresponding genes. The result confirmed that M-xa5and M-Xa23could recognize its corresponding genes specially, and molecular marker M5was non-specific to its gene Xa7;The F2population of cross between Xa23donor parent CBB23and common susceptive parent Ce253were selected by marker M-Xa23to identify their genotypes. For the research,231homozygous resistant individuals with200bp specific short bands were founded. And than F3of20individuals with excellent agronomic characters were selected for PCR amplification (M-Xa23) and bacteria inoculation (pathogenic types IV of Xoo), the identification of genotypes were highly consistent with their phenotypes, up to100%.