The Genetic Mapping Of SSR Markers On RIL Populations Of Common Buckwheat And The QTL Location Of Major Agronomic Traits

The recombinant inbred lines of common buckwheat were cultivated in thegrowth chamber of the Institute. Their eight agronomic characters (number ofbranches, plant height, yield per plant, seed set, thousand seed weight, flowerdiameter, seed length and width were measured and the relationships among themwere analyzed. Two populations including96plants of F5RILs (48for eachpopulation) developed by the Research Center and were used in this study for geneticmapping. On the basis of sequences of transcriptome data of buckwheat in theResearch Center, a great amount of SSR sequences were used for designing SSRprimers and ampilified. Based on the polymorphism SSR markers screened out fromthem, the genetic linkage maps were constructed. Finally, the QTL locations of someimportant agronomic traits were analyzed. The main results are as follows：(1) The analysis of agronomic traits： The results showed that yield per plant hasthe largest variation coefficient up to87.1%, and there are the significant positiverelationships between plant height and branch number, between yield per plant andseed set, between thousand seed weight and seed length, and between seed length andseed width. The seed set, the seed length, the seed width, the thousand seed weightand the total branches are all the major factors that influenced the yield per plant.Among them, seed set has the most effect.(2) SSR genetic mapping： On the basis of the population of recombinant inbredlines from the cross of Lorena-3×Homo, we constructed the genetic linkage mapof common buckwheat, including8linkage groups and185marker loci (All of SSRmarkers were first developed, total201marker loci and16of them cannot be assignedto any one of linkage maps). The map covered1254.9cM with an average distance of7.02cM, the maximum and the minimum genetic distance was30.7cM and2.1cM,respectively.On the basis of the population of recombinant inbred line from the cross of Homo×TianZi100, we constructed the genetic linkage map of common buckwheat, whichincluded10linkage groups and188marker loci (202marker loci in all and14of them cannot be assigned to any one of linkage maps). The map covered1495.6cM with anaverage distance of7.95cM, the maximum and the minimum genetic distance was33.6cM and2.1cM, respectively.After comparing all the SSR markers, we selected the common SSR markersshared by the above two genetic maps as anchor markers and then intergrated the twomaps into a new map. The new map had11linkage groups in all and369SSR markerloci. This map covered genome length of2051.5cM, with average distance of5.56cM, the minimum distance of0.3cM and the maximum distance of33.6cM.(3) The QTL analysis of agronomic traits： By using composite interval mappingmethod, in the population of recombinant inbred line from the cross of Lorena-3×Homo, we located the quantitative trait loci of some key traits. As the results, there are5QTLs of total number of branches,1QTLs of plant height,8QTLs of yield perplant,1QTLs of seed setting rate,5QTLs of thousand seed weight,4QTLs of flowerdiameter,3QTLs of the seed length and6ones of the seed width.In the population of recombinant inbred line generated through the cross of Homoand Tianzi-100, we positioned the quantitative trait loci of these traits. As the results,total2QTLs of total number of branches,4QTLs of plant height,8QTLs of yield perplant, no QTLs of seed setting rate,7QTLs of weight per thousand of seeds,6QTLsof diameter of flower,4QTLs of the length of and2QTLs of the width of seed. QTLloci trended to cluster together on linkage map.Additionally, the result of QTL position showed that the agronomic traits withsignificant positive correlation shared linkage QTL loci, suggesting that geneticlinkage may be the foundation of extreme significant correlation among theseagronomic traits.(4)The analysis of SSR markers gene for agronomic traits QTL location： Theresults showed that the agronomic traits were influenced by correponding genes, thatis: the number of branches by cytokinin O-glycosyltransferase gene, the height ofplant, the length and width of seed by LRR receptor-like serine/threonine proteinkinase gene, the yield per plant by serine/threonine protein kinase gene or GATAtranscription factor gene, the seed set by heat shock protein gene, the weight of thousand seeds by serine/threonine protein kinase gene, and the diameter of flower byAP2ethylene response transcription factor.