Construction of the BAC Physical Map on Wheat Chromosome 6B for its Sequencing

For the purpose of better understanding the genome structure of wheat and accelerating the development of DNA markers for gene isolations and future breeding, the Japanese research consortium, as a member of IWGSC, is now conducting physical mapping and genomic sequencing of chromosome 6B of Chinese Spring wheat. With a sequence-based finger printing method (Whole Genome Profiling^TM) and contig assembly using the FingerPrinted Contigs software, physical maps for the short and long arms of chromosome 6B have been successfully established from the 6BS- and 6BL-specific BAC libraries, respectively, that consist of ca. 700 BAC contigs with an estimated chromosomal coverage of more than 85% of the entire physical length of both arms. Overlap analysis between the neighboring clones within BAC contigs resulted in a total number of ca. 10,000 minimal tiling path BACs along the whole chromosome. For the validation and chromosomal landing of the BAC contigs onto their corresponding genomic regions, we currently developed a large number of 6B-specific DNA markers using the public marker resources, available EST databases, and the 6B survey sequence. To date, BAC contigs covering more than 80% of chromosome 6B have been anchored to the specific genomic regions on chromosome 6B. In parallel, a high-resolution radiation hybrid map, a deletion map and a genetic map are under development for further improvement of physical maps. This work was supported by grants from the Ministry of Agriculture, Forestry and Fisheries of Japan (Genomics for Agricultural Innovation; KGS1001 and KGS1003) and funding from Nisshin Flour Milling Inc..