Genetic Analysis Of Some Grain Yield And Quality Related Traits In Barley

Barley(Hordeum vulgare L.)is one of the world?s earliest domesticated crops and ranks the fourth cereal crop after maize,rice and wheat.Barley is widely used throughout word in many ways,including animal feed and material for malting and brewing by industry.High grain yield and quality are the main objectives to develop cultivars in breeding programmers.Most agronomic traits related to grain yield are controlled by quantitative loci(QTL).However,the traditional breeding selection is not often very efficient.The research of genetic characteristics and mapping of quantitative trait locus(QTL)in these yield and quality traits make it now possible to apply to the genetic improvement of yield and quality of barley in Marker assisted selection(MAS).The mapping population consists of 122 doubled haploid(DH)lines derived from a cross between the six-rowed dwarfing barley cultivar Huaai 11 and the two-rowed barley cultivar Huadamai 6.10 agronomic traits(length of main spike,MSL;spikelet number on main spike,SMS;spikelet number per plant,SLP;grain number per plant,GP;grain weight per plant,GWP;grain number per spike,GS;thousand grain weight,TGW;grain weight per spike,GWS;spike density,SPD and spike number per plant,SP),grain protein content(GPC)and pasting properties of starch were analyses for QTL mapping in the DH population.The results are as follows:1.The t-test showed that two parents were significant difference on all traits(p < 0.05)but grain number per plant(GP).Grain number per plant(GP)is determined by spike numbers per plant(SP)and grain number per spike(GS).Because Huaai 11 had more grain number per spike and few spike number per plant,it could explained that the complex the trait of grain number per plant(GP)in DH population was significant different although parents showed no significant different in the year 2011.Probabilistic of the distribution test showed nine traits(excluded SMS)displayed normal distribution with skewness and kurtosis of among-1 from 1(Table 1)and spikelet number on main spike(SMS)displayed bimodal distribution.2.A total of 221 QTLs underlying these traits were detected in five consecutive years using composite interval mapping(CIM)method.In year 2009,50 QTLs were detected on the genetic map for the 10 traits.QTLs were distributed on 1H,2H,3H,4H,5H and 7H.The detected QTLs accounted for 1.27%-78.76% phenotypic variations and LOD for each trait ranged from 2.52 to 65.83.In 2010,48 QTLs were detected for 10 traits,and were distributed on seven linkage groups.The detected QTLs accounted for 1.07%-82.22% phenotypic variation,and LOD for each trait ranged from 2.56 to 87.42.In 2011,41 QTLs were detected for 10 traits,and were distributed on seven linkage groups.The detected QTLs accounted for 1.13%-72.76% phenotypic variation,and LOD for each trait ranged from 2.58 to 54.54.In 2012,41 QTLs were detected for 10 traits,and QTLs were distributed on seven linkage groups.The QTLs accounted for 2.00%-79.08% phenotypic variation and LOD for each trait ranged from 2.55 to 67.58.In 2013,41 QTLs were detected on the genetic map for the 10 traits and distributed on 1H,2H,3H,4H,5H and 7H.The QTLs accounted for 1.35%-79.50% phenotypic variation,and LOD for each trait ranged from 2.69 to 65.66.3.The comparison between QEI mapping and single-environment mapping in our population using composite interval mapping(ICIM)method.The result showed that QTL stability and QEI levels can be analyzed directly by referring to QEI mapping results.Most QTL detected by single-environment mapping can also been detected in QEI mapping.Estimates of effects and position were similar in both mapping,but estimates from QEI mapping more reliable.4.The QTLs associated for these observed traits were generally clustered on chromosome 2H,4H,5H and 7H.Three main QTL cluster regions associated with agronomic traits on chromosome 2H,4H and 7H were detected.The QTLs for spikelet number on main spike(SMS),spikelet number per plant(SLP),grain number per plant(GP)and grain weight per plant(GWP)were located in the region near the row number gene Vrs1 on chromosome 2H.Spikelet number per spike(SMS),spike density(SPD)and spike number per plant(SLP)were clustered on chromosome 4H.On the terminal of chromosome 7H,there was a QTL cluster associated with thousand grain weight(TGW),spike density(SPD),grain weight per plant(GWP)and grain weight per spike(GWS).5.Total of 31 QTLs underlying these traits were detected underlying grain protein content and pasting properties of starch using composite interval mapping(CIM)method.In 2010-2013,six QTLs associated with grain protein content were detected.The most consistent q Gpc7-1 was detected in the long arm of chromosome 7H,the sequence of SNP hit the Nud1 gene on chromosome arm 7HL and this gene adhering hulls is controlled by an ERF family transcription factor gen regulating a lipid biosynthesis pathway.20 QTLs were detected for pasting properties of starch.The detected QTLs accounted for 1.93%-46.62% phenotypic variation,and LOD for each trait ranged from 2.51 to 6.78.