DETECTION OF 5S-RDNA AND OTHER REPEATED DNA ON SUPERNUMERARY B-CHROMOSOMES OF TRITICUM SPECIES (POACEAE)

The supernumerary B chromosomes of Tritticum speltoides and T. tripsacoides were analyzed in mitotic metaphases of spike primordium cells by C-banding and in situ hybridization (ISH) analyzes. B chromosomes of T. speltoides have larger telomeric and interstitial C-bands, whereas those of T. tripsacoides are almost completely devoid of C-bands. A prominent ISH site of rye related DNA sequences (using probe pSc119) was detected on B chromosomes of T. tripsacoides and only a minor ISH site was observed on the T. speltoides B chromosomes. However, two ISH sites of 5S rRNA loci were detected at a terminal and an interstitial location of the T, speltoides B chromosomes. These sites were absent on B chromosomes of T. tripsacoides. The results are discussed with respect to the phylogenetic origin of these B chromosomes.