Quantitative Trait Loci Associated with Resistance to Rice Stripe Virus and Small Brown Planthopper Infestation in Rice

Rice stripe is a serious viral disease of japonica rice (Oryza sativa L.) cultivars in Asia. Resistance to this disease can be divided into that to rice stripe virus (RSV) and to the pest (small brown planthopper, SBPH). Here we have used a doubled-haploid (DH) population bred from the cross Zhaiyeqing8 (ZYQ8) x Jingxi17 (JX17) and four separate inoculation methods to genetically dissect the rice stripe resistance present in ZYQ8. Two linked RSV resistance quantitative trait loci (QTLs) were located on chromosome 1, and one on chromosome 11, jointly explaining 30 to 44% of the trait variance. The main-effect qSTV11 was mapped close to the established RSV resistance gene Stvb-i. For resistance to SBPH, three QTLs were located, mapping to chromosomes 1, 2, and 11, and jointly explaining 44 to 51% of the trait variance. The large-effect qSBPH1 appears to be a novel QTL conferring a degree of tolerance and antibiosis against SBPH. The positive alleles at all six QTLs were present in ZYQ8. Analysis of a set of chromosome segment substitution lines (CSSLs) in which chromosomal segments of various indica varieties were present in a japonica background showed that rice stripe resistance genes/QTLs are common on the long arm of chromosome 1.