Construction Of Molecular Genetic Map Identification And Mapping Of QTLs Related To Drought In Wheat Backcrossing Introgression Lines

Increasing wheat production is the main way to protect our food security.Drought stress is a primary environment constraint greatly impacting wheat production.Analysis of drought-related traits in wheat and their genetic mechanisms and selecting and breeding high-yielding wheat NILs carrying drought-tolerant traits may provide a basis for breeding high-yielding varieties.In this study,a wheat introgression lines generated form repeat backcross[(Lumail4xShanhan8675)xLumai14](BC3F5)were used as plant materials.The wheat drought-tolerant traits,including plant height,spike length,spike number per plant,heading date,first internode length,length from flag leaf pulvinus to spike base,relative first internode length,relative length from flag leaf pulvinus to spike base,fructify spikelet number per spike,sterile spikelet number at top,sterile spikelet number at spike bottom,Grain number per spike,grain weight per plant,thousand-grain weight were identified under different water conditions by SSR molecular markers and QTL for drought-related traits were mapped Reveal wheat drought-related traits the genetic basis and QTL expression pattem.Below is the result:1.700 SSR markers were used to analyze the polymorphism between parents.Of all 208 SSR markers showed polymorphism,which reached 29.71%of effective amplification reaction.The genetic background of Lumai14 was 92.9%in this IL access to its theory value 93.8%by genotype detection.2.According to the Somer's international wheat consensus SSR map,192 markers were mapped in the linkage map of the IL.178 makers presented one introgressed line at least,accounted for 92.71%of polymorphic markers.The amount of polymorphic markers ranged from 5 to 13 in each chromosome.And every chromosome contained 9.14 markers in average.The average length between two markers was 13.38 cM.The chromosome 5D contained 13 markers,while the 4B were only 5 markers.Total of 160 ILs were selected to detect introgressed segment.One to Forty-six donor fragments were identified in the each line,average of 8.04 in each line.The length of the introgression fragment ranged from 12.8 cM to 940.3 cM,the average length 133.7 cM.The donor genome of Lumai 14 was represented between 0.5%and 38.7%in the ILs.3.The ILs phenotypes of Fourteen wheat drought-related traits were analysised.Coefficients of variation for all traits in ILs ranged from 0.05%to 225%under two water regimes.The averages of most traits in ILs presented the tendency to be more adjacent to the recurrent parent Lumai14.As can be seen from the character variation range,Most traits of ILs exhibited transgressive segregation except FNS under well-watered and SNP GNS and GWP under rainfed condition.But all traits showed exceed recurrent parent Lumai 14,which maybe due to the introgression of favorable alleles from non-recurrent parent Shanhan8675.All correlation coefficients for ILs traits were significant except SST between the rained and the well-watered conditions.4.All 78 additive QTLs and 187 epistasis QTLs for drought-tolerant-related traits were distributed in all chromosomes except 1D.The A-QTLs controlling 2 traits were located next to the markers Xbarc5(2A)?Xwmc144(2D)?Xwmc41(2D)?Xwmc169(3A)and Xcfd14(7D).A-QTLs controlling 3 or more traits were located next to the markers Xwmc 134(1B)?Xwmc757(4A)?Xbarc3(6A)and Xwmc201(6A).Both some A-QTLs and AA-QTLs were located next to the markers Xbarc148(1A)?Xwmc134(1B)?Xwmc201(6A)and Xbarc3(6A).Among these QTLs,QPH.cgb.6A.4?QSL.cgb.2A.2?QLPSB.cgb.6A.4?QSST.cgb.3A.4 ? QTGW.cgb.6A.5 had greater contribution rates of phenotypic variation explanation than others,ranging from 9.03%to 17.33%.These loci could be major QTLs for drought-related traits.Due to the detection of epistatic QTL effect more and larger,less its additive QTL effect is small.And,epistatic effect play a major role on wheat drought-related traits.5.QTL hot region is formed in some sections on the chromosome.Total of 9 hot-spot regions consisted A-QTLs and 30 AA-QTLs were found.Among those,the hot-spot regions located closet to the region in 1A between Xgwm136?xbarc83?Xbarc148?Xwmc312 and Xgwm497,1B between Xwmc134?Xbarc81 and Xwmc776,2A between Xbarc5,2B between Xgwm501,2D between Xwmc144 and Xwmc41,3A between Xwmc169,4A between Xwmc757 and Xgwm610,5A between Xwmc524 and Xgm410,Xwmc145?Xwmc256?Xbarc3 and Xwmc201 in 6A and Xcfd14 in 7D,had become important hot-spot regions controlling significant wheat drought-related traits,which indicated these regions contained large amount of target gene.In this study,a wheat introgression lines(IL)generated form repeat backcross[(Lumai 14×Shanhan 8675)×Lumail4](BC3F5)were used as plant materials.Some stable expressed QTLs were detected,These QTLs are located near the markers Xwmc757(4A),Xwmc201(6A).These QTLs also had important application in QTL-NIL building,QTL functional research and map-based cloning.