Chromosomal Localization of Virulence in Brown Planthopper that Break Down the Rice Resistance Gene BPH26

The brown planthopper (BPH), Nilaparvata lugens (Stål), is the most destructive insect pest of rice. Virulent biotypes of BPH, which were able to break resistance genes in rice, have obviously threatened rice productions in Asia. The recent findings suggest that the virulence of BPH is controlled by major genes. In this study, the relative chromosomal location of a virulence-associated gene in BPH against a near-isogenic rice line carrying the resistance gene BPH26 was assigned to the BPH chromosome. A total of 78 female offspring of the F₂ population derived from the cross between avirulent and virulent inbred strains was used to map the gene. Quantitative trait locus analysis of the honeydew excretion and the appearance of abdomen using simple sequence repeat markers detected one locus on linkage group 14 that accounts for 48% of the virulence phenotypes. This study constitutes a discovery of a BPH effector gene which overcomes the resistance conferred by BPH26, the gene encodes a coiled-coil-nucleotide-binding-site-leucine-rich repeat (CC–NBS–LRR) protein. The identification of this locus will leads to acquisition of information on the relationship between resistance in host plant and virulence of BPH.