Preliminary Mapping Of Quantitative Trait Loci For Brown Planthopper Resistance In The Offspring Of Guangxi Oryza Rufipogin Griff

Brown planthopper(Nilaparvata lugens St?l, BPH) has become the most destructive pests of ricewordwide. BPH usually causes seriously decrease of rice yield per year in China. At present, identifying and utilizing endogeneous rice BPH-resistance genes from rice germplasms to develop resistance varieties is an economical, efficient, and envirioment-friendly way to manage BPH.BR96 is a BPH resistance variety derived from Guangxi common wild rice. In this study, a F2:3 population with 142 families derived from a cross of BR96 and BPH suspective variety Bai56 was acquired. A total 113 pairs of polymorphic SSR markers between BR96 and Bai 56, which uniformly covering the whole rice genome, was got by screening 700 pairs of SSR markers. Then the 113 pairs of polymorphic SSR markers were usied to analyze the genotype of each family in the F2 population of BR96/Bai56. The mean of BPH resistant level of each family of F3 population was identified through the standard seedbox screening technique as the resistant level of the corresponding F2 family. Then the genetic linkage map and the quantitative trait loci( QTLs) of BPH resistance were obtained based on the maker geneotypes and the the pheontypes of BPH resistance were analyzed by Map Maker / Exp 3.0 and Windows QTL Cartographer 2.5.The main results in the study are as follows:1. The average resistance scores of the brown planthpper of BR96 and Bai 56 were 2.9 and 8.6 respectively, indicated that BR96 was a highly resistant variety and Bai 56 was a highly susceptible variety.2. The interval between more than 70% markers is less than 20 c M in the genetic linkage map that we constructed.3. The average BPH resistance scores of each family in F2 population of BR96 / Bai 56 were continuous and non-normal distribution. There are peaks between 5.0-5.9 and 8.0- 8.9.4. QBph4 was detected in the chromosome 4 between the molecular markers RM16605 and RM16717, with a LOD value of 28.7, explaining 29.4% of the phenotypic variation. The additive effects of the allele from BR96 was 2.18. QBph4 may be a major BPH-resistane QTL with the largest effect among the three QTLs identified in this study.5. QBph3 was detected in the long arm of chromosome 3 between the molecular markers RM489 and RM282, with a LOD value of 4.1, explaining 4.13% of the phenotypic variation. QBph6 was detected in the short arm of chromosome 6 between the molecular markers RM276 and RM527, with a LOD value of 2.6, explaining 7.3% of the phenotypic variation. The additive effects of QBph3 and QBph6 are from the allele from BR96. QBph3 and QBph6 may be two minor BPH-resistane QTLs, explaining 10.9% of the phenotypic variation collectively.6. We have gotten 6 BC1 populations derived from the backcross of Bai 56 and highly resistant families in the F2 population of BR96 and Bai 56 to construct BC2F2 population next. Screening for recombinant events between marker RM16605 and RM16717 in BC2F2 population, we can narrow down the region of QBph4 with analysis of genotype s and the pheontypes of BPH resistance. Our results lay the foundation of marker-assisted selection for bredding BPH resistance varieties and cloning resistance gene further.