Mapping Of Blast Resistance Genes In Latisail And Marker-Assisted Selection Breeding

Harness blast-resistance genes and growing resistant varieties have been proved to be the most effective and economical means to control rice blast disease while good resistance donor is necessary for resistant breeding . Molecular marker assisted selectuion(MAS) is a highly efficient approach in resistance breeding programs while markers closely linked to the resistant genes is indispensable. Here ,we mapped the blast resistance gene in rice cultivar Latisail possessing broad-spectrum resistance ,coming from global molecular breeding program and made use of the closely linked makers in MAS, which created new material, developed new cultivar for molecular resistance breeding. Main research results are as follows:1. After Latisail,MS8S and BC₂F₂ populations were inoculated by 97054 and 2004114A, we identified their resistance.and found the seedings displayed two distinct phenotypic groups :resistant and susceptible, respectively, .The ratio of the two BC₂F₂ groups fit well to the expected ratio (3:1) of single locus Mendelian segregation , which indicated that Latisail had one dominant resistant gene to control 97054 and 2004114A.2. A linkage analysis using SSR was performed in a BC2F2 mapping population through bulked-segregant analysis (BSA) in combination with recessive-class analysis (RCA).Out of 344 SSRs were selected from 12 rice chromosomes equally used to analyze the polymorphism, 178 SSRs, which the proportion is 51.7%, have polymorphic and were used to look for the marker linked to resistant gene , only one marker, RM594 on chromosome 1, was found to have linkage with the resistant gene with the genetic distance is 3.1cM.3. The genotype of 10 resistant individuals randomly derived from the population was the same with that of Latisail when RM594 was used to identify, therefore, it showed that RM594 can be used in MAS. In addition,we analysed the background recover rate of the 10 individuals by 178 polymorphic SSRs.As a result, individual 1 and individual 6 have higher background recover rate and can be used further backcross for developing resistant NILs and resistant MS8S sterile lines.