Fine organization of genomic regions tagged to the 5S rDNA locus of the bread wheat 5B chromosome

• DOI: 10.1186/s12870-017-1120-5
• Publication Date: 2017-11-14T09:24:57Z
• Authors: Ekaterina M. Serg...; Andrey B. Shcherban; Irina G. Adonina; Michail A. Nesterov; Alexey V. Beletsky; Andrey L. Rakitin; Andrey V. Mardanov; Nikolai V. Ravin; Elena A. Salina
• Keywords: Polyploid; Genomic Organization; Concerted evolution; Pyrosequencing; Bacterial artificial chromosome

The multigene family encoding the 5S rRNA, one of most important structurally-functional part large ribosomal subunit, is an obligate component all eukaryotic genomes. rDNA has long been a favored target for cytological and phylogenetic studies due to inherent peculiarities its structural organization, such as tandem arrays repetitive units their high interspecific divergence. complex polyploid nature genome bread wheat, Triticum aestivum, technically difficult task sequencing clusters repeats mean that detailed organization extended genomic regions containing rRNA genes remains unclear. This despite recent progress made in wheat sequencing. Using pyrosequencing BAC clones, this work we studied two distinct rDNA-tagged 5BS chromosome wheat. Three BAC-clones were identified chromosome-specific BAC-library aestivum. results assembling, obtained six rDNA- contigs with total length 140,417 bp, sets (pools) individual sequences belonging separate, but closely located on chromosome. Both are characterized by presence approximately 70–80 copies rDNA, however, they completely different organization. first region contained highly diverged short-type disrupted multiple insertions transposable elements. second more conserved long-type organized single array. FISH using probes specific both unit types showed differences distribution intensity signals chromosomes species diploid progenitors. A established. These differ neighboring comprised elements, implying modes evolution these regions.