Genetic Analysis Of QTL Mapping And Heterosis For Seeding Traits And Spike Related Traits

To map quantitative trait loci （QTL） of coleoptile length, radicle length, chlorophyllcontent, five spike-related traits and heterosis loci （HL） related to the grain number per spike（GNS） and grain weight per spike （GWS）,168double haploid （DH） population derived fromHuapei3×Yumai57and an immortalized F₂population （IF₂） generated by randomlypermutated intermating of these DH lines were investigated. The results provided generesources for molecular marker assisted selection and molecular aggregation breeding bydesign, and provide information for marker-assisted selection strategy in hybrid wheatbreeding.The main results were as follows:1. A set of168doubled haploid （DH） lines were derived from a cross between Huapei3andYumai57. The hybridization experiments were carried out in May. The168DH lines wererandomly divided into two groups through random permutation. Lines in one group wererandomly paired with lines in the other group to make crosses with a condition that eachof the168DH lines was used only once in the crosses. This procedure was repeated twotimes, resulting in168combinations. One hundred and sixty-eight true F1lines wereobtained, which constituted the IF₂population used.2. Based on inclusive composite interval mapping （ICIM） method, we identified11additiveQTLs for CL and12additive QTLs for RL using168IF₂population lines under normaland the three stress conditions. Each QTL explained4.93%–35.37%of the phenotypicvariance. QTL QCl3D located between Xcfd223and Xbarc323was detected in bothnormal and20%PEG-6000treatments, and explained phenotypic variances of7.83%and11.74%, respectively. On chromosome6D, two QTLs for CL and RL were found in theinterval between Xswes679.1and Xcfa2129, and the favorable allele was contributed byYumai57.3. Six additive QTLs were detected for chlorophyll content using DH and IF₂populations.There were three QTLs in DH and IF₂population, respectively. The QTLs of chlorophylla content and chlorophyll b content in DH population were mapped to the Xcfd101-Xbarc320intervals on chromosome5D. QTLs of IF₂population were identifiedin Xwmc492-Xcfd223interval on chromosome3D, and they were major additive QTLs.4. Using DH and IF₂populations,18,14,17,17and10QTLs were detected for spike length（SL）, spikelet number per spike （SNS）, spike compactness （SC） grain number per spike（GNS） and grain weight per spike （GWS） in four environments, respectively. Each QTLexplained3.25-58.58%of phenotypic variation. Senven QTLs observed on chromosome6B for SL and SC were located in the same loci.5. A total of17and13HLs were detected for GNS and GWS, respectively. The HLs of GNSwere identified on chromosome1B,2B,3A,5B₁,5D,6A and6D. QHgns1B-2, QHgns2Band QHgns6A-1were detected in two environments and expression stably. HLs of GWSwere located on chromosome2B,4A,5D,6D,7B₁and7B₂. Each HL explained2.4-26.0%of the heterosis phenotypic variation. And the HL QHgws2B、QHgws4A andQHgws7B₂were detected in two environments.