| Spike number per plant (PN), grains number per spike (GNS) and thousand grainsweight (TGW) were the wheat yield factors. The F2and F2:3populations derived from thecross between Chinese Spring and Lankaodali were chosen as research subjects. Afteranalyzing the mixed major gene and poly-gene genetic model and mapping QTL on PN, GNSand TGW, the genotypes and genetic effects of superior lines (SL) were predicted. And thestudy could provide the selection method of improving wheat yield for breeder, make thefoundation for developing the markers about PN, GNS and TGW, and offer the possibility ofmarker-assisted selection. This study obtained the following results:1. A F2:3population including327lines and derived from the cross between Chinese Springand Lankaodali was developed, which were grown in Yangling, Qishan and Qianxianareas, respectively, whose PN, GNS and TGW in a wild range of genetic variation weresuitable for genetic analysis and QTL mapping.2. The genetic analysis for the PN, GNS and TGW of the F2:3population were accomplishedusing mixed major gene plus poly-gene model of quantitative traits. Results showed thatthe PN was controlled by one additive-dominance major gene (the A-1model) and theTGW was controlled by no major gene (the A-0model) in three environments. Moreover,the GNS was controlled by two major genes (the B-1model) in Yangling area, while itwas suit for the A-0model in Qishan and Qianxian areas.3. Totally,129polymorphic primers of SSR were used to mark the F2population andconstruct the genetic map with21linkage groups. This genetic map covered the geneticdistance of2965cM, with an average primer interval of22.98cM.4. Based on the constructed genetic linkage map, this research improved the method forspotting about denatured polyacrylamide gel electrophoresis in detecting SSR. As long asbands of high specificity, the markers could be analyzed by the method of twice spotting.This method could save41%time and50%reagent and be suitable for genetic mapping.5. Based on the constructed genetic linkage map and the investigation of the main yield traitsfrom Yangling, Qishan and Qianxian areas, QTL analysis of the F2:3population for the PN,GNS and TGW were conducted. The QTL mapping for the PN results indicated a total of nine QTLs were detected in three environments. Among them, the major gene wasQPn4B-2. The combined analysis of the PN in three environments showed that no maineffects but strong epistatic effects of five QTLs were detected, and the individual analysisindicated that seven QTLs had genetic and environment interaction effects, so theirepistatic effects were largely contributed to the PN as well as genetic and environmentinteraction effects. Two QTLs were indentified for the GNS, which just had oppositeadditive effects and were similar in the contribution ratio of the corresponding QTL effect.Also, eight QTLs were indentified for the TGW, all which had additive effects fromLankaodali and were similar in the contribution ratio of the corresponding QTL effect, sothe TGW was controlled by polygene.6. In this study, two important chromosome regions were also found. The QTLs for the PNand TGW were located in the maker interval Wms135-Wms136on the chromosome1A,and the QTLs for the GNS and TGW were located in the maker interval Wms495-Wms338on the chromosome4B. Moreover, two QTLs for the PN were detected on thechromosome4B. Therefore, those regions might play an important role in the wheat yield.7. Based on QTL mapping, the genotypes and genetic effects of superior lines (SL) werepredicted. The results about the PN showed that the genetic effects of predicted superiorgenotype improved by1.45as compared with that of Chinese Spring, when excluded theeffects of genetic and environment interaction. When the effects of genetic andenvironment interaction were under consideration, the genetic effects improved by1.45,1.9937and1.45, respectively in Yangling, Qishan and Qianxian areas, among which thehighest genetic effects value was up to3.9542in Qishan area, so the progeny could havepotential for improving the PN. The superior genotype in the QPn2A and QPn6B locus inQishan area were different from that in another two areas, this indicated that the superiorgenotype of the PN was affected by environmental factors. The results about the GNSshowed that the genetic effects of predicted superior genotype improved by4.0054ascompared with that of Lankaodali, while the estimated population mean was38.7103, sothe progeny could have little potential for improving the GNS. However, because thegenetic effects of predicted superior genotype about the TGW improved by23.5489ascompared with that of Chinese Spring, the progeny could have great potential for improving the TGW. And the superior genotypes combinations of general superior linewere predicted, and the study mainly discussed the way to obtain superior lines inbreeding. |
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