| Sunflower is a globally important oil crop and cash crop,and improving yield is one of the main objectives of sunflower breeding.In order to analyze the molecular genetic mechanism of yield-related traits in sunflower and to explore effective molecular markers and genes,this study used 150 sunflower recombinant self-incompatible line populations constructed from oil crop sunflower K55 and K58 as parents as research materials.The genetic linkage map was constructed and combined with the phenotypic data obtained from two years of replicated field trials to conduct phenotypic analysis,QTL localization analysis and candidate gene screening and function prediction for nine yield-related agronomic traits,including plant height,disc diameter,stem thickness,number of leaves,number of grains per disc,number of empty grains per disc,grain weight per disc,100 grain weight and fruit set rate.The main findings are as follows:1.Analysis of the two-year phenotypic data from the RIL population showed a high degree of variation among the strains,with coefficients of variation ranging from 14.66%to 86.58%,with a large range of variation.The correlations among the traits were highly significant or significantly positive,except for the number of empty particles and the seed setting rate,so all the other eight traits were key factors in determining sunflower seed yield,except for the number of empty grains in a single disc.Cluster analysis clustered the test materials into four major groups,including 37 low-yielding groups,67medium-yielding groups,41 medium-high-yielding groups and seven high-yielding groups.2.A total of 10 QTL loci(LOD≧2)for eight traits were detected in two years of environment,including two main effect QTL with >10 % contribution and eight micro-effect QTL loci,explaining 0.004% to 13.075% of phenotypic variation,distributed on nine chain clusters 4,5,7,8,9,13,14,16 and 17,with no QTL loci detected on other chain clusters.No QTL loci were detected in other chains.The majority of the additive effect values for the eight traits were positive,i.e.the alleles that increased the phenotypic value of the trait were all from the parent K55,while a few alleles with negative effect values were also present from the parent K58.3.The stem thickness QTL locus Qsd17 was detected within Marker125344-Marker128610 on chromosome 17,and the QTL locus Qngp17 for single disc grain number was also detected in this interval with a contribution rate of 13.075%,which is greater than 10% and is a master QTL locus,and Qsd17,Qngp17 and Qhgw5,Qgw16 contributed more to the phenotype than other QTL loci and were suitable for further candidate gene mining.4.A total of 14 candidate genes were identified within four QTL loci,Qsd17,Qngp17,Qhgw5 and Qgw16,using bioinformatics methods.One was associated with stem thickness,seven with the number of grains particles,one with grain weight and five with100 grain weight.These genes are involved in carbohydrate processes and have functions such as E3 ubiquitin protein ligases and SAUR family proteins.5.The genes rna55361,rna13297 and rna13113 were identified in the functional annotation of candidate genes that could be the focus of later studies for cloning and functional validation of yield-related genes. |
