Pyramiding The Bacterial Blight Resistance Gene Xa23 And The Brown Planthopper Resistance Gene Bph20(t) By Molecular Marker-assisted Selection

Rice(Oryza sativa L)is one of the most important cereal crop in the world,which provides stable food for about half of the global population. Bacterial blight(BB)and brown planthopper(BPH)are the major rice disease and insect pest.At present,using molecular Marker—assisted selection breeding resistant varieties is considered as the most economical and effective approach to control the rice disease and Pests.In this study,we used the rice variety BPH54 containing brown planthopper resistant gene bph20(t)as donor parents,the elite and bacterial blight resistance gene Xa23 restoring lines 1711 as recipient parents.The Xa23-linked EST Marker C189 was used to select Xa23 and the bph20(t)-linked SSR Marker By17 was used to select bph20(t)in the segregating populations.Main results are summarized as follows:1.The polymorphism analysis indicated that C189 and By17,highly combined with Xa23 and bph20(t)respectively,can be used to Marker-assisted select between 1711 and the BPH54 hybridization rice parents in this study.2.According to the results observed after inoculating bacterial blight strains(the high poisonous strain P6),the recipient parents 1711 showed highly resistant.3.By the Marker-assisted selection and traditional breeding technology, through continuous cross,self-cross and back-cross,we had obtained 28 plants containing Xa23 and bph20(t)in BC₂F₂.4.According to the results observed after inoculating bacterial blight strains(the high poisonous strain P6),26plants showed highly resistant and 2 plants showed moderately resistant.5.16 of the 28 plants containing Xa23 and bph20(t)in BC₂F₂ were identified the resistance to BPH,But their resistances need more research.