Inheritance and QTL mapping of antibiosis to green leafhopper in rice

Nephotettix virescens Distant (green leafhopper: GLH) is one of the major insect pests of rice (Oryza sativa L.) in the temperate rice growing region of Asia. The objective of this study was to determine the chromosome locations of some GLH-resistance genes and conduct genetic analysis of GLH resistance. From a cross between the japonica cultivar Taichung65, which is susceptible to GLH, and indica cultivar ARC10313, which is resistant to GLH, 125 recombinant inbred F₁₀ lines (RIL) were developed. Quantitative trait loci (QTLs) for antibiosis to GLH were detected on chromosomes 3,5,11, and 12. The QTL near XNpb292 on chromosome 12 for GLH mortality was from the japonica cultivar, while the other three QTLs on chromosomes 3, 5, and 11 were from the indica cultivar. The percentages of observed phenotypic variance attributable to the major QTLs on chromosomes 3 and 11 were 25.3% and 56.8%, respectively. These two QTLs were close to two green rice leafhopper (GRH, Nephotettix cincticeps Unler) resistance genes, Grh4 and Grh2, respectively. Using NILs (near isogenic lines) of Grh4 and Grh2, we determined that the interaction of these two GRH resistance genes expressed strong resistance to GLH. Four GLH-resistance QTLs, including two major QTLs linked to XNpb144 on chromosome 3 and G146S on 11, respectively, were identified in this study, and these two major QTLs were located close to Grh2 and Grh4. It may be possible to pyramid these genes to improve resistance to both GRH and GLH.