Abstract
A Sri Lankan indica rice (Oryza sativa L.) cultivar Rathu Heenati was found to be resistant to all the four biotypes of the brown planthopper (BPH) (Nilaparvata lugens Stål). In the present study, we constructed a linkage map to identify the locus (loci) for the BPH resistance genes, using an F2 population from a cross between Rathu Heenati and a susceptible cultivar 02428. Insect resistance was evaluated using 156 F2:3 lines and the genotype of each F2 plant was inferred from the phenotype of the corresponding F2:3 lines. Three loci detected by QTL (quantitative trait locus) analysis, were assigned to chromosomes 3, 4 and 10. The phenotypic variance of the three QTLs indicated that the QTL on chromosome 4 is a major BPH resistance gene in Rathu Heenati. Through linkage analysis, it was found that this BPH resistance gene was located between two SSR markers RM8213 and RM5953 on the short arm of chromosome 4, with map distances of 3.6 cM and 3.2 cM, respectively. This gene, tentatively designated as Bph17, should be useful for the breeding of varieties resistant to BPH in a marker-assisted selection (MAS) program.
