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

Abstract

An introgression line derived from an interspecific cross between Oryza sativa and Oryza officinalis, IR 54741-3-21-22 was found to be resistant to an Indian biotype of brown planthopper (BPH). Genetic analysis of 95 F₃ progeny rows of a cross between the resistant line IR 54741-3-21-22 and a BPH susceptible line revealed that resistance was controlled by a single dominant gene. A comprehensive RAPD analysis using 275 decamer primers revealed a low level of (7.1%) polymorphism between the parents. RAPD polymorphisms were either co-dominant (6.9%), dominant for resistant parental fragments (9.1%) or dominant for susceptible parental fragments (11.6%). Of the 19 co-dominant markers, one primer, OPA16, amplified a resistant parental band in the resistant bulk and a susceptible parental band in the susceptible bulk by bulked segregant analysis. RAPD analysis of individual F₂ plants with the primer OPA16 showed marker-phenotype co-segregation for all, with only one recombinant being identified. The linkage between the RAPD marker OPA16₉₃₈ and the BPH resistance gene was 0.52 cM in coupling phase. The 938 bp RAPD amplicon was cloned and used as a probe on 122 Cla I digested doubled haploid (DH) plants from aIR64xAzucena mapping population for RFLP inheritance analysis and was mapped onto rice chromosome 11. The OPA16₉₃₈ RAPD marker could be used in a cost effective way for marker-assisted selection of BPH resistant rice genotypes in rice breeding programs.