Identification of a tandemly repeated DNA sequence using combined RAPD and FISH in welsh onion(allium Fistulosum)

A tandemly repeated DNA sequence was identified and characterized by the combined RAPD and FISH data from a total genomic DNA of Welsh onion (Allium fistulosum). A clone containing this repeating sequence was selected and sequenced. This repeating unit of 314 bp inserted into pAf 072 contained 54.1% adenine and thymine residues, and showed the primer sequence used, 5‐GAAACGGGTG‐3’, in both terminals of the sequence. Fluorescence in situ hybridization using this tandemly repeated sequence as a probe indicated that the detected sites were coincident with the major C‐banded constitutive heterochromatin in the terminal regions of both arms of all 16 chromosomes