Genetic Analysis And QTL Mapping For Major Agronomic Traits And Resistance To Barley Yellow Mosaic Virus In Barley DH Population

Barley is the fourth largest cereal crop in the world,which is not only widely used for food and feed,but also used for malting,brewing and healthcare product.The breeding objectives vary with diverse characteristics of different barley varieties.The genetic analysis and QTL mapping for main agronomic traits are benefical to improve the selection efficiency in barley breeding.A total of 173 doubled-haploid(DH)lines generated from a cross between a six-rowed Chinese landrace Yangsimai 1 of feed barley and a two-rowed cultivar Gairdner of malting barley.The DH population and its parents were planted in three places across two.grown seasons to identify quantitative trait loci(QTL)controlling agronomic traits,such as plant height(PH),spike length(SL),top first internode length(TFIL),grain number of single row(SRG),spike number per plant(SPP),grain density(GD),thousand-kernel weight(TKW)and row type(RT)as well as resistance to barley yellow mosaic virus.Genotype analysis of DH population was carried out by SSR markers,and genetic linkage map was constructed.The main results are as follows:1.A total of 91 pairs of SSR primers were screened from 1008 pairs of SSR primers with obvious polymorphism between the parents and distinct amplified bands.The genotypes of DH population were analyzed to construct a genetic linkage map including 91 pairs of SSR markers.The number of linkage groups was equal to that of barley chromosomes.The total length of the map was 1161.99 cM.The average genetic distance between the loci was 12.77 cM,and the number of markers on each chromosome arranged from 11 to 16.2.The DH population represented basically normal distribution in PH,SL,TFIL,SRG,SPP,GD and TKW.There.were significant differences in major agronomic traits between Yangsimai 1 and Gairdner except PH and SPP.In the DH population,there were extremely significant negative correlations between RT and SRG,RT and TKW as well as SL and GD,which were-0.772,-0.863 and-0.827,respectively.There were extremely significant positive correlations between PH and TFIL,as well as SRG and TKW,which were 0.771 and 0.708,respectively.3.QTL mapping for major agronomic traits in barley DH population was carried out.A total of 28 QTLs were detected,including 13 QTLs existing only in one environment and 15 QTLs in two environments,among which 9 QTLs explaining more than 10%of the phenotypic variation responsible for PH,SL,TFIL,SRG,GD and TKW,respectively.There were four concentrated regions of QTL.4.QTL analysis for barley yellow mosaic disease index(DI)in the DH population was performed.Nine QTLs for the DI of barley yellow mosaic disease were identified,including five QTLs mapped on chromosomes 1H and 2H with contribution rate more than 10%.Furthermore,among the five QTLs,qRYM-1Ha,qRYM-1Hc,qRYM-2Ha and qRYM-2Hb were detected in two years.As to the QTLs for resistance to barley yellow mosaic disease,qRYM-1Ha and qRYM-4Ha,located on 1H and 4H,were linked to the markers Bmac0213(19.31cM)and EBmag0701(75.95cM),respectively,which may be new genes resistant to barley yellow mosaic disease.