QTL Analysis Of Yield-related Traits In The Population Derived From Rapeseed Variety Dadi 199

Rapeseed is the third largest oil source in the world(USDA,2016),and it is also the largest oil crop in China.Under the situation of the continuous expansion of the size of urbanization and the further reduction of the cultivated land area,continually improving rapeseed yield per unit area is the inevitable requirements.Most of yield-related traits are quantitative traits,which controlled by multiple genes.QTL mapping of yield-related traits by using high density genetic linkage map has great effect on clarifying the basis of yield formation and improving the yield of rapeseed.Dadi 199 is a new variety with high yield and high oil content,which derived from the cross of ZS11×R11(ZS11 and R11 have excellent agronomic traits,however,and there are large differences among plant height,silique length,silique seeds density,seed coat color,resistance,and so on).Based on the doubled haploid population(DH population)by microspore culture with 280 lines derived from Dadi 199,a high-density genetic linkage map of Brassica napus L.(2n=38)was constructed.This map was used to identity QTL by combined with the phenotype of 15 yield related traits in 4 environments.The main conclusions are as follows:1.Based on the doubled haploid population(DH population)with 280 lines derived from the cross of ZS11×R11,the acquired total number of SNP was 3359647,the final effective SNP number was 1122653,and the effective polymorphism was 33.42% by the whole genome resequencing of the 280 DH lines and two parents,a high-density genetic linkage map of Brassica napus L.(2n=38)was constructed,which was made up of 19 linkage groups,including 16341 bin markers,covering 2200.145 cM in total with an average interval of 0.135 cM between adjacent loci.The length of all linkage groups varied from C01 of 87.310 cM to A05 of 170.718 cM,an average interval of between adjacent loci varied 0.063cM(A03)to 0.357cM(A10),and the number of markers varied from 251(A10)to 1688(A03).2.Variance analysis results in the two way of 15 yield related traits of DH population under 4 environments showed that 15 yield related traits were highly significant(P<0.01)among genotype,environment,genotype and environment under the 4 environments.Among all the yield related traits,thousand seed weight(TSW)had the largest narrow-sense heritability,which reached 92.32%,while harvest index(HI)had the least narrow-sense heritability,which was only 63.08%.3.Composite interval mapping method of Windows QTL Cartographer V2.5 was employed in QTL analysis of 15 yield related traits including plant height,main inflorescence effective siliques and so on.A total of 568 QTLs were mapped on 17 linkage groups for 15 traits with LOD?2.5.102 RS-QTLs were detected,mapped on 17 linkage groups(except C04 and C09 linkage groups).Phenotypic variation explained by the single putative QTL varied from 2.04% to 21.13%.4.Seven main effect RS-QTLs was detected for 15 traits,including 3 RS-QTLs controlling thousand seed weight,2 RS-QTLs controlling silique length and 2 RS-QTLs controlling silique seeds density,mapped on A07,A08 and A09 linkage groups,explaining 12.88% to 21.13% of phenotypic variation.1 RS-QTL of thousand seed weight(qTSWA07-1)had negative additive effect,1 RS-QTL of silique length(qSLA09-3)had negative additive effect,and 1 RS-QTL of silique seeds density(qSSDA09-3)had negative additive effect,all synergistic effect were from the parent R11;1 RS-QTL of silique seeds density(qSSDA09-8)had positive additive effect,2 RS-QTLs of thousand seed weight(qTSWA09-3,qTSWA09-5)had positive additive effect,and 1 RS-QTL of silique length(qSLA08-1)had positive additive effect,all synergistic effect were from the parent ZS11.5.6 RS-QTLs clusters(C1 to C6)were detected in 102 RS-QTLs,distributed on 5 chromosomes(A03,A06,A09,C06 and C07),which contained 21 RS-QTLs,accounting for 20.59% of the total number of RS-QTLs.Each RS-QTLs cluster contained 3 to 5 RS-QTLs.