Molecular cytogenetic analysis of DNA sequences with flanking telomeric repeats in Triticum aestivum cv. Begra.

A cloned genomic DNA fragment (pTa241) formerly derived from a DNA fraction obtained from isolated nuclei of embryos of a Polish cultivar of wheat (Triticum aestivum cv. Begra) comprises a tandem repeat of the telomeric array CCCTAAA, and hybridizes in situ exclusively to the telomeres of all chromosome arms of the somatic chromosome complement of wheat. A second cloned fragment (pTa637) derived from the same fraction is 637 bp long, flanked by 28 bp of the same telomeric repeat unit, and hybridizes in situ to the entire lengths of all the chromosomes of the complement. The same pattern of hybridization was observed when the flanking telomeric sequences were removed. A third DNA fragment (pTa1439), derived from unfractionated genomic DNA and flanked with 62 bp of the same telomeric unit, showed the same patterns of distribution. Together with additional evidence from Southern analysis, these observations were interpreted to mean that these sequences are associated with mobile DNA elements and are distributed widely throughout the genome. The chromosomal distribution of the non-telomeric parts of the clones is consistent with the dispersed genomic distribution characteristic of transposons and retroelements.