| Wheat(Triticum aestivum L.)is the second largest grain crop in the world.However,with the increase of population,the decrease of cultivated land area and the frequent occurrence of extreme climate,wheat yield is affected and national food security is threatened.Therefore,it is still the primary task of wheat breeding to explore wheat yield potential and cultivate high-yield and high-quality wheat varieties.In this study,216 recombinant inbred lines(RILs)constructed by Heshangtou(HST)and Longchun 23(LC23)were used as materials,which were planted in Yangling of Shaanxi,Zhangye of Gansu,Nanyang and Luoyang of Henan,respectively.The grain traits of wheat at maturity in these four environments were identified.These 216 materials were genotyped by wheat 55 K SNP gene chip to construct a high-density genetic linkage map covering 21 chromosomes of wheat.QTL(Quantitative Trait Locus)mapping of grain weight related traits was carried out by using the complete interval mapping method,in order to find stable,major and independent genetic background related trait gene loci,and develop closely linked molecular markers,so as to provide reference for further fine mapping and molecular assisted breeding methods to improve wheat yield.The main findings are as follows :1.The 55 K SNP chip of wheat was used to genotype the parents and RIL population,and a high-density genetic linkage map was constructed.The total length was 4543 c M,including 22 linkage groups,covering 21 chromosomes of wheat,with an average genetic distance of 1.7 c M.The number of markers in A genome(38.6%)and B genome(41.7%)was much more than that in D genome.The correlation analysis with the Chinese Spring reference genome IWGSC Ref Seq v1.0 showed that the marker order was relatively consistent with the marker order of wheat genome assembly,and the Pearson correlation coefficient was 0.77～0.99(P < 0.001).2.A total of 51 QTLs were detected under four environments and BLUP data sets in the population of Heshangtou / Longchun 23.A single locus could explain 0.44% ～20.13% of the phenotypic variation,and the LOD value was 3.00～59.43.There were 9 QTLs with phenotypic variation interpretation rate greater than 10% and could be detected in multiple environments(3 environments and above).There were QTL clusters with obvious effects on chromosomes 2D and 7D,which were significantly associated with multiple traits such as1000～grain weight,grain width,plant height and heading date.Qtkw.nwafu-2D.1 could explain 7.19% ～12.92% of the phenotypic variation,with a physical interval of 20.08Mb～47.89 Mb;Qtkw.nwafu-7D could explain 7.53% ～13.26% of the phenotypic variation,with a physical interval of 65.50 Mb～75.23 Mb.3.According to the functional markers and physical intervals,Qtkw.nwafu-2D.1 and Qtkw.nwafu-7D were associated with photoperiod gene Ppd-D1 and vernalization gene Vrn-D3(Ta FT),respectively.Qtkw.nwafu-7D has better environmental stability;there was a significant additive interaction between Qtkw.nwafu-2D.1 and Qtkw.nwafu-7D,and the polymerization of the two loci had significant additive effects on 1000～grain weight and grain width.4.Qgl.nwafu-5A could explain 4.56% ～17.86% of the phenotypic variation.The LOD value was 3.93～59.63,and the physical interval was 0.65 Mb ～ 0.75 Mb,which was located in the recombination hotspot and closely linked to the molecular marker AX-111067709.In the natural population significance test of 242 wheat varieties(lines),it was proved that this locus was significantly correlated with grain length and grain weight,which could increase grain length by 3.33% ～ 4.59%(P < 0.001)and grain weight by 5.70% ～10.35%(P < 0.05)in different environments.Qgl.nwafu-5A was widely selected in the winter wheat region of northern China,which could increase grain length by 3.41% ～5.49%(P < 0.01)and grain weight by 7.38% ～8.47%(P < 0.05)in different environments.These results laid a foundation for molecular assisted selection breeding of Qgl.nwafu-5A. |
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