Characterization Of Genetic Population And QTL Analyses In Wheat

Genetic linkage map construction is the groundwork for germplasm resources evaluation,agronomically important gene/QTL mapping and cloning and molecular maker assistant selection.Establishment of various genetic populations and molecular marker technologies provided effective toolsfor genetic linkage map construction. The objectives of this research were characterizing the RILpopulation under different locations to make reference for population use, and constructing geneticlinkage map using the characterized population and DArT markers. Furthermore, QTL analyses for someyield components and grain quality traits were to carry out. This could be of significance to furtherunderstand the genetics of yield and quality characters and to improve cultivars in wheat. The mainresults are as follows:Two Australian varieties, Lang and CSCR6RIL, were used to yield a RIL population. Thepopulation and their parents were planted at two locations, Zhangbei, Hebei and Anyang, Henan, withvaried ecological factors. The trends of trait performance and variation of parents were basically thesame at two environments. CSCR6, the male parent, showed bigger spikes and more grains. Its spikelength, spikelet number and grain number per spike were with higher means than those of Lang, thefemale parent. Differences also existed in grain protein content, wet gluten, hardness, falling number andtest weight between Lang and CSCR6. The lines of RIL population showed more abundant variations intwo environments, and normal distributions for eight tested traits of interest. These traits were allquantitatively inherited traits, and thus meet the requirements of genetic mapping.There were positive or significantly positive relationships between spikelet number and spikelength, grain number per spike, and between grain protein content and wet gluten, as well as betweenfalling number and test weight. However, the negative correlations were found between protein contentand hardness, and falling number and wet gluten, and wet gluten and test weight. Among yield andquality characters, the significantly positive correlations were between spike length and test weight,falling number. The correlations between grain number per spike and protein content, wet gluten werenegative or significantly negative. All the correlations suggested that the genes controlling the relatedtraits might be of linkedly inheritance or one gene with more effects.By use of320DArT markers and89F7lines of RIL, genetic linkage map was constructed withcomposite interval mapping, including39linkage groups. The longest group was83.78cM, the shortest4.14cM. The map covered610.18cM of wheat genome. All groups were anchored to19chromosomes,1A、1B、1D、2A、2B、3A、3B、3D、4A、4B、4D、5A、5B、6A、6B、6D、7A、7B、7D。Twenty-five QTLs were screened out from the data of two environments. Of which, six QTLswere detected for protein content at Zhangbei environment, explained6.73%~14.43%of the phenotypicvariation. It was also found that four QTLs for wet gluten (explained11.71%~16.12%of the phenotypicvariation), one QTL for hardness (explained13.05%of the phenotypic variation) and one QTL forfalling number (explained9.71%of the phenotypic variation) existed. In Anyang environments, a QTLfor spike length with9.43%phenotypic variation explanation, five QTLs for grain number per spike with6.81%~19.39%phenotypic variation explanation, three QTLs for protein content with7.64%~10.19%phenotypic variation explanation, three QTLs for wet gluten with6.80%~15.54%phenotypic variation explanation and a QTL for hardness with9.26%phenotypic variation explanationwere found. These25QTLs were located on chromosome1B、2B、3A、3D、4A、4B、4D、6A、7A、7B.