Analysis of Quantitative Trait Loci for Resistance to Brown Planthopper in Dongxiang Wild Rice (Oryza rufipogon Griff.)

Abstract

The wild species in genus Oryza are important resources of genes resistant to brown planthopper (Nilaparvata lugens, BPH). The objective of this study was to identify quantitative trait loci (QTLs) in Dongxiang wild rice (O. rufipogon Griff.). A BC₁F₅ population and a BC₃F₃ population were developed for QTL mapping from the cross between Dongxiang wild rice and an indica rice cultivar, Xieqingzao B (O. sativa L. subsp. indica) as the recurrent parent. The BC₁F₅ population was infested with BPH collected from paddy fields. Two QTLs were identified, of which qBph2 was located in the interval of RM29-RG157 on chromosome 2 and qBph7 in the interval of RM11-RM234 on chromosome 7. The alleles from Dongxiang wild rice on qBph2 and qBph7, which explained 21.8% and 67.1% of the phenotypic variations, respectively, and reduced seedling mortality by 22.2% and 43.7%. These QTLs were validated using the BC₃F₃ population infested by BPH biotypes I, II, and III. This result shows that qBph2 confers resistance to biotypes I and II, and qBph7 confers resistance to biotypes I and III. Both QTLs show a great potential for improving BPH resistance in rice cultivars.