Development And Evaluation Of Brown Planthopper Resistance Gene Pyramiding Lines And Fine Mapping Of Bph31 In Rice

The brown planthopper(Nilaparvata lugens St?l,BPH)is a typical phloem-feeding insect and is one of the most devastating insect pest on rice,be harmful to rice yield and the quality of rice.Nowadays,34 BPH genes have been reported and 8 of them were cloned in rice.Exploring new BPH genes and breeding and planting cultivars with BPH genes are the most economical and effective strategies for BPH prevention.However,only a few BPH genes have been used for rice breeding and most cultivars are single-BPH-gene cultivars,which is hard to meet the demand of rice production and pest control.Our study is to construct different double-gene pyramiding lines by 7 single-BPH-gene 9311-NILs and markerassisted selection(MAS),evaluate their effects by combining phenotype with agronomic traits,and fine mapping a new gene Bph31.Our main results are as follows:1.We used 7 BPH-gene-NILs of 9311(QBph3-NIL,QBph4-NIL,Bph6-NIL,Bph9-NIL,Bph17-NIL,Bph20-NIL and Bph24-NIL)and crossed each other,finally obtained 20 double-BPH-gene pyramiding lines by molecular marker assisted selection(MAS).According the phenotypes of resistance response,most double-gene pyramiding lines showed great improvement of resistance.QBph3/Bph9,Bph6/Bph9,QBph3/Bph20,QBph3/Bph6,Bph24/Bph6,Bph20/Bph6 and Bph20/Bph9 showed high resistance against with brown planthopper,with scores 1.70?1.82?1.87?1.93?1.95?1.95 and 2.00.The other pyramiding lines showed resistance with scores from 2.50 to 3.50.The scores of NIL are from 2.50 to 3.50.Similarly,double-gene pyramiding lines also showed great improvement of resistance in BPH survival ratios,with ratios lower than 40%.BPH survival ratios of NIL are from 40% to 62%.2.We fine-mapped Bph31 to chromosome 11 and a region of 210 Kb,between markers In77 and In88,by analysing the genotype and phenotype of the recombinants.