Validation Of Quantitative Trait Loci For Resistance To Brown Planthopper And Whitebacked Planthopper In Rice And Its Application In Breeding

Wild species of Oryza is an important resource of the genes for resistance to brown planthopper (BPH)and whitebacked planthopper (WBPH). Identify new resistance genes, breed and utilize the host plantresistance are considered to be the most economical and efficient method to control BPH.First of all, The BC3F3population developed from Xieqingzao B (XB)//XB/Dongxiang wild rice(Dwr) BC1F5population, was conducted to validate two quantitative trait locus (QTL) for resistance toBPH and WBPH, Which were previously mapped in RM29RG157on chromosome2andRM11RM234on chromosome7, respevtively. The population had an isogenic background ofXieqingzao B except segregated in the RM29RM250region on chromosome2, the RM164RM3870region on chromosome5, the RM11RM234region on chromosome7and the RM215RM245regionon chromosome9. The BPH population applied was three single BPH colony which was biotype I,biotype II and biotype III. The BC3F3populaiton contained195lines were evaluated to measuredseedling mortality using the standard seeding box screening technique (SSST). Two linkage maps,RM29RM250on chromosome2and RM11RM234on chromosome7were constructed using BC3F3population, which containing5SSR markers and2SSR markers, spaning74.5cM and24.9cM,respectively. The seedling mortality evaluated using BC3F3populaiton was varified the two QTLs effect,that was qBph2confering resistance to biotypes I and II, and qBph7resistance to biotypes I and III.Secondary, seven plants screeing from BC3F3population were applied to validate QTL (qWbph9)concerning resistance to WBPH located in RM215RM245on chromosome9. The seven plants showXB genotype at RM215while Dwr genotypes at RM245, RM1026and RM205. The BC3F4were grownwith12plants per line in Lingshui, Hainan Province, China (LS). At maturity, two seed samples werecollected from each line. When an identical phenotype was observed among the12plants of a line, seedfrom a single plant were collected as one sample and those from the remaining plants were mixed as theother. When segregation was observed, two single plants showing distinguishable phenotype wereharvested respetively. By applied the WBPH population collected from the paddy field at ChinaNational Rice Research Institute, Hangzhou Zhejiang Province, China, the test materials were measuredfor seedling mortality using SSST. The SAS GLIMMIX procedure was used to esimate the effect andmake comparison of test lines with the recurrent parent XB. The result showed that the all14linesdecresase of seedling mortality at the1%significance level.In addtion, Three lines selected from BC3F3population carrying qWph9introgression segment fromO.rufupogon was backcrossed to XB for one generation, and followed by three generations of selfing.As a result of single nucleotide polymorphism (SSR) detetion and phenotype examination,5candidatemaintainers (BC4F4) were obtained. The evaluation of resistance to WBPH shows that the all strainsseleceted significantly decreased the seedling mortality. Its indicate that the resistance alleles derivedfrom Dwr had introgress into clutivated successfully. In2013, the5strains were ground in LS by5rowswith12plants per rows, and the heading day and plant height were calculated. At maturity, plants were harvested by using five point sampling mode to muasured number of panicles per plant(NP), grainlength(GL), grain width(GW),1000-grain weight (TGW), number of filled grains per panicle (NFG),spikelet fertility (SF) and grain yield per plant(GYD). Analysis of variance showed that there was nosignificant difference between B9with XB, except HD and GL. While the other4strains had lowerTGW and higher NP when compare with XB. Those materials have a great potential application incultivation.