A major QTL for resistance to green rice leafhopper (Nephotettix cincticeps Uhler) derived from African rice (Oryza glaberrima Steud.)

The green rice leafhopper (GRH), Nephotettix cincticeps Uhler, is a serious insect pest of cultivated rice (Oryza sativa L.) in temperate East Asia. An African rice cultivar, Oryza glaberrima Steud. (IRGC104038), was shown to be highly GRH-resistant at the booting stage. To reveal the genetic basis of the GRH resistance in O. glaberrima, a BC₁F₁ population derived from a cross between a susceptible japonica variety, Taichung 65 (T65), and O. glaberrima was analyzed by quantitative trait locus (QTL) analysis. A single major QTL for GRH resistance, designated qGRH9, was detected on rice chromosome 9, and three minor QTLs were detected on rice chromosomes 3, 7, and 10. A series of O. glaberrima introgression lines (GILs) containing IRGC104038 chromosome segments in the T65 genetic background were evaluated to confirm the genetic effects of the QTLs, and three GILs carrying qGRH9 showed resistance to GRH. Substitution mapping using the GILs revealed that qGRH9 was located between simple sequence repeat (SSR) markers RM215 and RM2482 in a 1.39-Mbp region on the distal region of the long arm of chromosome 9, and tightly linked to RM7306. These SSR markers maybe useful for marker-assisted selection of qGRH9 for improvement of GRH resistance in rice.