Step by Step Analysis of Wheat Chromosome 5B: New Data

The genetic and bioinformatics resources which were developed during construction of physical map of 5B chromosome within the framework of the IWGSC strategy are useful instruments facilitating in understanding wheat gene and genome structure and evolution. In our work 660 ISBP and 215 SSR markers were developed for physical mapping based on low coverage 454 sequencing of short arm of 5B chromosome (5BS) and on Ion-Torrent sequencing of 134 selected BAC clones from the minimal tiling path (MTP) overlapping BAC clones of 5BS. Two populations from a cross of CS and CS-5Bdic (F2 – 366 plants and 116 Recombinant Inbred Chromosome Lines -RICLs) were generated during this work. About 45% of 5BS supercontigs were anchored based on: (i) screening of 43776 BAC clones of the 5BS library by 63 ISBP and SSR markers, (ii) mapping the F2 and RICLs population using the Illumina Infinium 15k Wheat platform, and (iii) GenomeZipper approach. More than 1020 out of 3161 MTP BAC clones have been sequenced using the Roche/454 platform.

Special screening of 5BS BAC library and primary structure analysis revealed 1-2 copy of 5S DNA repeat units (nearly 480 bp each) as a part of three scaffolds with a total length 233480 bp, indicating the difficulties in identification of tandem repeats. Novel candidate genes for flowering time regulation have been detected in the pericentromeric region of 5B as results of phenotyping and genotyping of RICLs.

The work was supported by the Russian Ministry of Education and Science (agreement 14.604.21.0106; identification number RFMEFI60414X0106).