Construction Of Genetic Linkage Map Of Wheat And QTL Mapping Of Yield Traits Based On SRAP Markers

Wheat (Triticum aestivum L.,2n=42, AABBDDgenomes) is an allohexaploid specieswith seven groups of homoeologous chromosomes. The wheat grain yield and other importantagronomic traits are generally controlled by multiple genes and influenced by environmentcondition．Grain shape traits including grain length(GL),grain width(GW)as well as grainthickness(GT)and1000-grain weight(KGW)are quantitative traits.With the development ofmolecular markers,location and expoiting QTL have become an important and essentialcomponent element in crop genetic improvement．the work will not only prepare generesources for molecular marker assisted selection and molecular breeding by design,but alsolay a foundation for fine mapping and clone some important genes．At present,It is the focusof attention by wheat breeders to explore the major genes of controlling of wheat grain shapeand1000-grain weight.In this study, Using statistical analysis software DPS v7.05forparents,F1and F2populations on behalf of yield-related traits in the correlation analysis andcluster analysis.And, Genetic linkage maps were constructed based on SSR(simple sequencerepeats)markers and SRAP(sequence-related amplified polymorphism) markers．The QTLmapping analysis of related traits was conducted by MICM(mixed—model based compositeinterval mapping)method in the F2populations．Main results showed as follows：(1)Correlation analysis in both F2populations indicated that GL was a highlysignificantly positive correlation with GW,GT and KGW,GW showed a closely significantlynegative correlation with GT and KGW, GT had a highly significantly positive correlationwith KGW.In this paper,we only study the relationship of grain shape traits and KGW,othertraits are ignored.(2) A genetic linkage map of2708.21cM is constructed．Total50loci aredistributed in14linkage groups of21chromosomes of wheat．The average distancebetween markers is30.43cM．(3) A mapping consisting of128F2populations derived from a cross between littlegrain wheat Chinese Spring and large grain wheat XiNong817was used for QTL mapping ofyield-related traits. A total of50QTL involving1A,2A,2D,3B,4B,4D,5D,6A,6D and7A wheat chromosomes and5linkage groups were identified for these four traits. Amongthem,16,13,10and11QTL for GL, GW, GT and TGW were identified, respectively. Inaddition,15genomic regions with plenty of QTL were detected on1A,2D,4D,5D,6A,7A and4linkage groups in this study. In the present study,50QTL for grain size and relatedtraits were detected, which will provide useful information for molecular assistant selection(MAS) in wheat genetic improvement(4) Analysis showed that the major QTL conferring grain shape and KGW in this studyhas not yet been isolated and pyramided,which will facilitate marker-assisted selection fornew large grain and high quality wheat varieties and map-based cloning in the future．...