Mapping of Quantitative Trait Loci of Ovicidal Response to Brown Planthopper(Nilaparvata lugens Stal) in Rice(Oryza sativa L.)

Abstract

The brown planthopper(BPH), Nilaparvata lugens Stal, is a serious pest of rice(Oryza sativa L.) in Asia. The rice ovicidal response to BPH is characterized by the formation of watery lesions which result in the death of the eggs. It is one of the factors affecting the suppression of the multiplication of BPH. To detect quantitative trait loci(QTLs) for this ovicidal response, a set of 71 rice recombinant inbred lines(F₁₁) derived from a cross between a Japonica variety Asominori with ovicidal response and an Indica variety IR24 without ovicidal response were phenotyped for grade of watery lesions(GWL) and egg mortality(EM) of BPH. GWL and EM showed a significant positive correlation(P<0.001) and transgressive segregation was observed for EM. In composite interval mapping for GWL and EM with 293 RFLP marker loci, two QTLs each on the long arm of chromosome 1(1L) and the short arm of chromosome 6(6S) were detected for both GWL and EM. The 6S QTL explained 72.1% and 85.1% of the phenotypic variantions for GWL and EM, respectively. The QTL on 1L explained 19.8% and 17.8% of the phenotypic variations for GWL and EM, respectively. Both alleles from Asominori increased GWL and EM. The Asominori allele at the 6S QTL was essential for the ovicidal response to BPH and the Asominori allele at 1L QTL could increase the EM of BPH in the presence of the Asominori allele at the 6S QTL. It is concluded that two RFLP loci, R1954 linked to 6S QTL and C112 linked to 1L QTL can be used for marker-assisted selection.