Genetic Mapping Of Aegilops Tauschii Coson

Common wheat (Triticum aestivum L., genome AABBDD,2n=6x=42) is an important food crop. Aegilops tauschii (2n=2x=14, genome DD), the D genome donor of common wheat, has many benefit genes for wheat improvement. Genetic map plays an important role in basic research and plant breeding. However, only few genetic maps for Aegilops tauschii was reported. Meanwhile, the differences in polyploid levels between a crop and its ancestral species may cause different expressions for a given gene, especially for a quantitative trait locus (QTL). Detecting QTL for Aegilops tauschii in hexaploid level, therefore, is needed in analyzing QTL for the purpose of common wheat improvement.In a previous study, tetraploid T. turgidum wheat PI377655was pollinated by diploid F1hybrids of Aegilops tauschii AS66×AS87and36interspecific triploid F1hybrids with genome ABD of PI377655//AS66/AS87were obtained. The36interspecific hybrids were self-pollinated to generate S1seeds of diploidization-hexaploid double haploid population (SynDH3) by spontaneous chromosome doubling with the help of unreduced gametes gene in PI377655. The aims of this experiment are to construct a high-density genetic map by SSR, DArT, SNP, and to detect QTL using this genetic population. The main results are as below:1. A total of1564polymorphism markers were obtained, including79SSR,351DArT,1122SNP, and one wax morphological marker.2. A total of1548(99%) markers were successful mapped into final map and formed eleven linkage groups, including76SSR (96.2%),351DArT (97%),1120SNP (99.8%), and one wax morphological marker. The total map length of seven D chromosomes spanned1132.66cM, with an average length of161.81cM per chromosome, and an average density of one marker per0.73cM. The longest and shortest map were7D (234.85cM) and4D (94.73cM), respectively. The1D and2D showed highest density with0.57and0.58cM/marker, respectively.3. In total, nine distortion loci were detected in seven chromosomes, included218SNP (19.5%),37DArT (10.5%) and12(15.8%) markers. The markers showing segregation distortion on chromosomes1D and4D were in favour of alleles originating from the parent AS87, whereas the markers showing segregation distortion on other five chromosomes were in favour of alleles originating from the parent AS66.4. ICIM analysis identified one QTL on chromosome1D, named Qsl.scau-1D. Qsl.scau-ID has a maximum LOD score of3.8and spanned by markers SNP1D-2and SNP1D-3.This QTL explained41.5886%of the phenotypic variation of the spiked length trait.Our study indicated that using diploid-hexaploid double haploid population is good in constructing high quality genetic map. However, the number of QTL detected is lower than our expected. Further works are needed to explain this phenomenon.