Molecular mapping and marker-aided selection of a gene conferring resistance to an Indian biotype of brown planthopper in rice

摘要

Brown planthopper (BPH) is one of the most destructive insect pests of rice in the Indian subcontinent, The BPH biotype of India is different from other known biotypes. The introgression line IR54741-3-21-22, developed from the cross of Oryza sativa/O. offieinalis, expressed a high level of resistance to BPH after testing at the Directorate of Rice Research, Hyderabad, India. The resistance in this line was controlled by a single dominant gene. DNA isolated from parents and individual F_2 plants wasamplified with 270 random amplified polymorphic DNA (RAPD) primers and polymerase chain reaction (PCR)-based RAPD polymorphism (dominant and codominant) was detected. Of the 19 primers producing a codominant type of polymorphism, only one primer (OPA16)could produce resistance- (938 bp) and susceptibility- (802 bp) specific bands in bulk segregant analysis, which indicated that the DNA marker OPA16_(938) might be a putative marker linked to the resistance gene. The resistance-specific 938-bp DNA fragment was cloned and long primers of 18-20 bp were developed, which produced specific PCR fragments cosegregating with resistance genes. The resistance-specific marker (938 bp) was mapped onto chromosome 11 of rice. The resistance-specific marker band was absent in most of the rice eultivars, except in Swarnalata, which showed the presence of a homologous 938-bp DNA fragment. The result indicated that the resistance gene in Swarnalata (Bph-6) may be the same as that in IR54741-3-21-22. The DNA marker OPA16_(938) would be useful in marker-aided selection.