Summary
Two different cloned repetitive DNA sequences derived from wheat (Triticum aestivum), one thought to be noncoding and the other coding for ribosomal RNA, were used as probes in in situ hybridisation experiments on genomes of diploid and polyploid Aegilops species. The noncoding repetitive sequence was found in variable amounts in all diploid species but restricted to specific “domains” or regions of the chromosomes. Deletions, amplifications and rearrangements have probably been responsible for this interspecific variation. Three diploid species, i.e., Ae. speltoides, Ae. longissima and Ae. sharonensis, related to the wheat B genome, possess many more copies of the sequence and their distribution is correlated with their respective C-banding patterns. The rRNA gene probe revealed that the nucleolar organiser regions in all polyploid species vary with respect to their frequency, size and location. These aspects of variation of rRNA gene sites probably arose through either the deletion of rRNA genes and/or chromosomal rearrangement.
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Teoh, S., Hutchinson, J. & Miller, T. A comparison of the chromosomal distribution of cloned repetitive DNA sequences in different Aegilops species. Heredity 51, 635–641 (1983). https://doi.org/10.1038/hdy.1983.75
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DOI: https://doi.org/10.1038/hdy.1983.75
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