AFLP Mapping Of The Rice Bacterial Blight Resistant Gene Xa-23

The rice near isogenic line (NIL) CBB23, harboring the rice bacterial blight resistance gene Xa-23, and the F2 population derived from a cross between CBB23 and JG30, the susceptible NIL of CBB23, were used to identify molecular AFLP markers linked to Xa-23 gene and subsequently determine its chromosomal location on the linkage map of rice. Bulked segregant analysis was performed using AFLP technique. Two bulked DNA samples were generated from F2 segregating population: one was resistant plant DNA pool, another was susceptible plant DNA pool.This two bulks were screened for polymorphisms using 128 AFLP markers. The results showed that three AFLP markers, named AP23,AP144 and AP111, are linked to the Xa-23 gene. Since AP23,AP144,AP111 showed polymorphisms between two bulks, 571 susceptible individuals of the F2 segregating population were further surveyed with all the three AFLP markers.By the analysis of the Mapmaker 3.0 software, the Xa-23 gene was located on the long arm of rice chromosome 11:1.0cM to AP23 near the CEN side, 0.8cM to AP144 and 5.1cM to AP111 on the other side. The four polymorphic bands were successfully clonded and sequenced.