title: RAPD and RFLP mapping of the bacterial blight resistance gene xa-13 in rice.
abstract: Bacterial blight (BB) caused by Xanthomonas oryzae pv oryzae (Xoo) is one of the most serious diseases of rice. The recessive gene xa-13 confers resistance to Philippine race 6 of Xoo. To tag xa-13 with molecular markers, RAPD analysis was conducted with the combined use of near-isogenic lines and bulked segregant analysis. From the survey of 260 arbitrary 10-nucleotide primers, one primer (OPAC05) was detected to amplify specifically a 0.9-kb band from the DNA of susceptible plants. The distance between the RAPD marker OPAC05-900 and xa-13 was estimated to be 5.3 cM. The RAPD marker was then mapped on chromosome 8 using a mapping population of doubled haploid lines derived from the cross of IR64/Azucena. The linkage between RFLP markers and the RAPD marker was analyzed using an F2 population of 135 plants derived from a cross between a near-isogenic line for xa-13, IR66699-5-5-4-2, and IR24. No recombinants were found between RZ28 and CDO116 and their distance from xa-13 was estimated to be 4.8 cM. RG136 was located at 3.7 cM on the other side of xa-13. The mapping of xa-13 with closely linked DNA markers provides the basis for marker-aided selection for rice improvement.
authors.affiliation: Division of Plant Breeding, Genetics and Biochemistry, International Rice Research Institute, P. O. Box 933, 1099, Manila, The Philippines.
authors.forename: G
authors.initials: G
authors.lastname: Zhang
authors.forename: E R
authors.initials: ER
authors.lastname: Angeles
authors.forename: M L
authors.initials: ML
authors.lastname: Abenes
authors.forename: G S
authors.initials: GS
authors.lastname: Khush
authors.forename: N
authors.initials: N
authors.lastname: Huang