QTL Mapping Of Marin Inflorescence Silique Number In Brassica Napus L

Brassica napus is an important oil crop in our country and even in the world.The current domestic production of rapeseed is far from meeting the demand,and the low price of rapeseed abroad has further stimulated the import of rapeseed.At present,in order to ensure food security,how to increase the yield of rape has become an urgent problem under the premise of keeping the cultivated land area unchanged.Among them,the analysis of the genetic basis of yield traits,mapping related genes,is to further promote high-yield rape premise.In this study,we used two RIL populations,’Kang Nongda’ × ’Zs11’ F6(KZRIL)and ’352’ × ’Zs11’ F6(TZRIL),to map QTLs for main inflorescence silique number,the markers were developed to analyze the genotypes of consistent QTLs stably expressed in multiple environments,and RIL lines with homozygous and consistent background QTL segments and different target QTL segments were selected for hybridization,the main results are as follows:1.Phenotypic analysis of yield-related traits in KZRIL and TZRIL populations:KZRIL and TZRIL populations were planted in six environments(15CD,15 EZ,15YL,16 EZ,17EZ,21Hz)for 4 years,and main inflorescence silique number of each family was investigated.Phenotypic data analysis showed that there was a wide range of genetic variation in main inflorescence silique number,which was a typical quantitative trait.Two-way analysis of variance showed that main inflorescence silique number of KZRIL and TZRIL populations was significantly affected by genotype and environment(p≤0.01).The generalized heritability of the two populations were 0.83 and 0.92,respectively.The results of correlation analysis showed that there was a significant positive correlation(P≤0.01)in main inflorescence silique number among different populations in different environments.2.Mapping analysis of QTLS for main inflorescence silique number in KZRIL population: A total of 17 QTLS for main inflorescence silique number were detected in KZRIL population in six environments,distributed on chromosomes A01,A02,A06,A09,C04,C06,C07 and C08,and the contribution rate of single QTLS ranged from 6.12%-22.86%.After integrating QTLS,four consistent QTLS were detected in multiple environments.Among them,KZRIL＿cq MFSN.A01 on chromosome A01 could be detected in both environments(16EZ and 17EZ),with a contribution rate of6.51% and a confidence interval of 30102635-31496851 bp.KZRIL＿cq MFSN.A06,located in chromosome A06,could be detected in four environments(15YL,16 EZ,17EZ,21HZ),respectively.The contribution rate was 8.95%,and the confidence interval was 44892998-45965807 bp.KZRIL＿cq MFSN.A09 on chromosome A09 could be detected in four environments(15EZ,15 YL,16EZ,17EZ),respectively,with a contribution rate of 11.81% and a confidence interval of 57587262-58802682 bp.KZRIL＿cq MFSN.C08 on chromosome C08 could be detected in two environments(16EZ and 17EZ),respectively,with a contribution rate of 7.95% and confidence interval of 2014882-2235768 bp.3.Mapping analysis of QTLS for main inflorescence silique number in TZRIL population:A total of 10 QTLS were detected in TZRIL population in six environments(15CD,15 EZ,15YL,16 EZ,17EZ,21HZ),distributed on chromosomes A07,A10,C03,C05,C08,and the contribution rate of a single QTL ranged from1.01% to 34.25%.The 10 QTLS for main inflorescence silique number detected by TZRIL population were integrated into 8 QTLS,including 2 consistent QTLS.Among them,TZRIL＿cq MFSN.C03,located in chromosome C03,was detected in two environments(17EZ and 21HZ)with a contribution rate of 24.54% and a confidence interval of 29102635-31430193 bp.TZRIL＿cq MFSN.C08 on chromosome C08 was detected in both environments(16EZ and 17EZ),with a contribution rate of 11.28%and a confidence interval of 1974319-2283908 bp.4.QTL integration in KZRIL and TZRIL populations: By re-integration of QTLS from different populations on the same chromosome,it was found that the interval of consistency QTL(KZRIL＿cq MFSN.C08)on KZRIL population coincided with that of consistency QTL(TZRIL＿cq MFSN.C08)on TZRIL population,which was named Cluster.C08,and the contribution rate was 10.12%.The confidence interval is2014882-2235768 bp.The additive effect of KZRIL＿cq MFSN.C08 was derived from parental ‘Kang Nongda’,and the additive effect of TZRIL＿cq MFSN.C08 was derived from parental ‘352’.5.Construction of derivative fine mapping population: According to QTL mapping results of host hornseed number in multiple environments,stable expression loci(KZRIL＿cq MFSN.A01,KZRIL＿cq MFSN.A06,KZRIL＿cq MFSN.A09,KZRIL＿cq MFSN.C08)were obtained in different environments.Markers were developed on both sides of each locus to analyze the genotypes of the population in the candidate interval.Under the condition of consistent control background,the derived positioning F2 population was constructed by homozygous single plant hybridization to provide materials for fine mapping of the candidate genes.