QTL analysis for the resistance to small brown planthopper (Laodelphax striatellus Fallen) in rice using backcross inbred lines

Small brown planthopper (SBPH) is a serious pest of rice (Oryza sativa L.) in China. An indica variety 'Kasalath' is highly resistant to SBPH. A mapping population consisting of 98 BC1F9 lines, derived from a backcross of 'Nipponbare'/'Kasalath'//'Nipponbare', was applied to detect quantitative trait loci (QTL) for resistance to SBPH. In the modified seedbox screening test, three QTLs for SBPH resistance were mapped on chromosomes 3 and 11, explaining 49.9% of the phenotypic variance. In the antixenosis test, a total of three QTLs conferring antixenosis against SBPH were detected on chromosomes 3, 8 and 11, which accounted for 36.4% of the total phenotypic variance. In addition, two QTLs expressing antibiosis to SBPH were detected on chromosomes 2 and 11, explaining 13.8% and 14.7% of the phenotypic variance, respectively. Qsbph11e, Qsbph11f and Qsbph11g were located in the region between S2260 and G257 on chromosome 11, indicating that the locus is significant in conferring resistance to SBPH in 'Kasalath'. The molecular markers linked to these QTLs should be useful in the development of varieties with horizontal resistance to SBPH.