Molecular tagging of a gene for resistance to brown planthopper in rice (Oryza sativa L.)

An introgression line derived from an interspecific cross between Oryzasativa and Oryza officinalis, IR54741-3-21-22 was found to beresistant to an Indian biotype of brown planthopper (BPH). Genetic analysisof 95 F₃ progeny rows of a cross between the resistant lineIR54741-3-21-22 and a BPH susceptible line revealed that resistance wascontrolled by a single dominant gene. A comprehensive RAPD analysisusing 275 decamer primers revealed a low level of (7.1%) polymorphismbetween the parents.RAPD polymorphisms were either co-dominant (6.9%), dominant forresistant parental fragments (9.1%) or dominant for susceptible parentalfragments (11.6%). Of the 19 co-dominant markers, one primer,OPA16, amplified a resistant parental band in the resistant bulk and asusceptible parental band in the susceptible bulk by bulked segregantanalysis. RAPD analysis of individual F₂ plants with the primerOPA16 showed marker-phenotype co-segregation for all, with only onerecombinant being identified. The linkage between the RAPD markerOPA16₉₃₈ and the BPH resistance gene was 0.52 cM in couplingphase. The 938 bp RAPD amplicon was cloned and used as a probe on122 Cla I digested doubled haploid (DH) plants from aIR64xAzucena mapping population for RFLP inheritance analysis and wasmapped onto rice chromosome 11. The OPA16₉₃₈ RAPD markercould be used in a cost effective way for marker-assisted selection of BPHresistant rice genotypes in rice breeding programs.