RFLP analysis of introgressed chromosomal segments in three near-isogenic lines of rice for bacterial blight resistance genes, Xa-1, Xa-3 and Xa-4

Introgressed chromosome segments in three near-isogenic lines (NILs) of rice for bacterial blight resistance genes Xa-1, Xa-3 and Xa-4 with the genetic backgrounds of an IR24 variety were measured by using restriction fragment length polymorphic (RFLP) markers and linkage map. The size of the introgressed segment flanking Xa-1 of a NIL was estimated to be 3.3-11.7 cM of map units. Both NILs for Xa-3 and Xa-4 contained the donor segments at an identical end of linkage group corresponding to chromosome 11. We demonstrated in this study that these NILs were good materials to identify DNA markers tightly linked to these resistance genes and the RFLP markers tagging the resistance genes were useful in genetics and breeding on the disease resistance.