| QTL mapping of yield traits was carried out by using molecular markers in this paper. The main methods and results are as follows:(1) A population of 131 recombinant inbred lines (RILs), RIL-8, were created from the cross of Chuan35050 and Shannong483. The parents of RIL-8 are excellent germplasm in wheat breeding with large ear and good yield traits in Chuan35050 and excellent yield traits in Shannong483. RIL-8 population is suitable for mapping with great different phenotypes in yield traits and quality traits.(2) The parental genotypes were analysed with as many as 230 SSR primer pairs developed by Roder et al for detection of polymorphism. Of these, 203 primer pairs gave amplification products, the polymorphism of 50 primer pairs (24.6%) with 55 sites was amplified between the parents. Gel electrophoresis of high-molecular-weight glutenin subunit (HMW-GS) showed 3 polymorphic sites between the parents, in which Glu-Al, Glu-Bl and Glu-Dl coded respectively 1, 7-1-9 and 5+10 glutenin subunits in Chuan35050, Glu-Al coded no glutenin subunit and Glu-Bl and Glu-Dl coded respectively 7+8 and 2+12 glutenin subunits in Shannong483. Using these SSR markers and HMW-GS markers, we detected the polymorphism of 111 lines selected randomly from 131 lines of RIL-8. A marker genetic linkage map with 18 chromosomes and 51 polymorphic sites covered 1296.7 cM of wheat genome was carried out using Mapmarker/EXP 3.0.(3) All of the 131 lines of RIL-8 population and their parents were planted in four environments: environment 1, Taian 1999; environment 2 , Taian 2000; environment 3, Taian 2001 and environment 4, Yantai 2001.Nine yield trait phenotypes were investigated in these four environments. QTL mapping for the 9 yield traits was carried out using QTLMapper Version 1.0. The main results are as follows:Using the combined test of the four environments, 39 QTLs of additive effects distributing on 14 chromosomes were detected. The range of general contribution rate of additive effect QTLs for different traits is 1.83~27.24%, and the range of contribution rate of different single QTL is 1.06-8.93%. 41 interaction effects distributing on 18 chromosomes were obtained. The range of general contribution rate in interaction effects for different traits is 1.26-36.15%, and the range of contribution rate in different single interaction effect is 1.20-13.30%. Combination of additive effects and interaction effects can account for over 50% of genotypic variation in spikelet number per spike (SNS) and spike number per 50cm row (SNR), and over 40% in fertile spikelet number per spike (FSNS), 1000 grain weight (KGW) and ear length (EL), over 30% in plant height (PH), over 20% in sterile spikelet number per spike (SSNS) and less than 10% in grain weight per 50cm row (GWR) and grain number per spike (GNS).Using the test of single environmen, 38 QTLs of additive effects distributing on 16 chromosomes were obtained. The range of contribution rate in different single QTL is 5.08-19.89%; 52 interaction effects distributing on 17 chromosomes were obtained. The range of contribution rate in different single interaction effect is 4.51-57.14%, with contribution rate of 57.14% of interaction effect between locus 3D-1 and locus 7B-1 in environment 4.(4) The results of QTL mapping indicated that the inheritance of yield traits was very complex, the explanation as follows:Additive effects Except for sterile spikelet number per spike (SSNS), QTLs of additive effects were tested for all other traits, with 10 QTLs for 1000 grain weight (KGW).The large variance of the effect values and the contribution rate of QTLs indicated that the effects are difference for different QTLs.Interaction effects The values of and the contribution rates of interaction effects are larger than that of additive effects under the combined test and under the test of single environment. This indicated that interaction effects of QTLs are important for yield traits. Some sites of interaction effect QTLs are also the sites of additive efffct QTLs or linked wit...
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