The large bread wheat genome (1C approximately 17 Gbp) contains a preponderance of repetitive DNA and the species is polyploid. These characteristics together serve to hamper the molecular analysis of the wheat genome. Its complexity can, however, be reduced by using flow cytometry to isolate individual chromosomes, and these can be exploited to construct chromosome-specific BAC libraries. Such libraries simplify the task of physical map construction, positional cloning and the targeted development of genetic markers. Rapid improvements in the efficiency and cost of DNA sequencing provide an opportunity to contemplate sequencing the wheat genome by preparing sequence-ready physical maps for each chromosome or chromosome arm in turn. The quality of the chromosome-specific libraries depends on their chromosome coverage and the mean insert size. First-generation libraries suffered from a relatively low mean insert size, but improvements to the protocol have generated a second wave of libraries with a significantly increased mean insert size and better chromosome coverage. Each chromosome (arm)-specific library is composed of a manageable number of clones, and so represents a practical tool in the area of wheat genomics.

• MeSH
• chromozomy rostlin genetika   MeSH
• DNA rostlinná genetika   MeSH
• fyzikální mapování chromozomů MeSH
• genetické markery MeSH
• genom rostlinný MeSH
• genomika MeSH
• genová knihovna MeSH
• hybridizace in situ fluorescenční MeSH
• polyploidie MeSH
• průtoková cytometrie MeSH
• pšenice genetika   MeSH
• umělé bakteriální chromozomy genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

KEY MESSAGE: Making use of wheat chromosomal resources, we developed 11 gene-associated markers for the region of interest, which allowed reducing gene interval and spanning it by four BAC clones. Positional gene cloning and targeted marker development in bread wheat are hampered by high complexity and polyploidy of its nuclear genome. Aiming to clone a Russian wheat aphid resistance gene Dn2401 located on wheat chromosome arm 7DS, we have developed a strategy overcoming problems due to polyploidy and enabling efficient development of gene-associated markers from the region of interest. We employed information gathered by GenomeZipper, a synteny-based tool combining sequence data of rice, Brachypodium, sorghum and barley, and took advantage of a high-density linkage map of Aegilops tauschii. To ensure genome- and locus-specificity of markers, we made use of survey sequence assemblies of isolated wheat chromosomes 7A, 7B and 7D. Despite the low level of polymorphism of the wheat D subgenome, our approach allowed us to add in an efficient and cost-effective manner 11 new gene-associated markers in the Dn2401 region and narrow down the target interval to 0.83 cM. Screening 7DS-specific BAC library with the flanking markers revealed a contig of four BAC clones that span the Dn2401 region in wheat cultivar 'Chinese Spring'. With the availability of sequence assemblies and GenomeZippers for each of the wheat chromosome arms, the proposed strategy can be applied for focused marker development in any region of the wheat genome.

• MeSH
• býložravci MeSH
• chromozomy rostlin MeSH
• DNA primery MeSH
• DNA rostlinná genetika   MeSH
• genetická vazba MeSH
• genetické markery MeSH
• genomika MeSH
• jednonukleotidový polymorfismus MeSH
• mapování chromozomů * MeSH
• mikrosatelitní repetice MeSH
• mšice * MeSH
• pšenice genetika   MeSH
• rostlinné geny * MeSH
• syntenie MeSH
• umělé bakteriální chromozomy MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Rusko MeSH