Physical mapping of 5S, 45S, Arabidopsis-type telomere sequence repeats and AT-rich regions in Achillea millefolium showing intra-chromosomal variation by FISH and DAPI

Abstract

Achillea millefolium L. collected in Altai, Russia showed 2n=54 as a hexaploid chromosme number. The interphase and metaphase chromosomes had FISH signals and DAPI bands: FISH yellow-colored signals of the 5S and 45S rDNA and the Arabidopsis-type telomeres were obtained after the hybridization of the biotin labbelled probes of the 5S, pTa71 and the Arabidopsis-type telomere sequence repeats. The 5S rDNA signals consisted of 11 yellow-color signals at the secondary constriction of the sat-chromosomes, two large interstitial signals on the long arm of two chromosomes, and very small four signals on the long arm of four chromosomes. The interphase nucleus showed 11 deep and two faint yellow color signals of 5S rDNA sites. Eleven yellow color signals of the 45S rDNA sites were detected on the short arm of 11 chromosomes. The Arabidopsis-type telomere signals were located on the terminal region on the both arms of chromosomes, while some were located far from the chromosome arm on the external part of the satellites in the sat-chromosomes, three terminal signals in some chromosomal arms one signal instead of two in the other chromosomes. DAPI-positive bands were found on interphase nucleus and 42 chromosomes, of which ten were terminal on both arms, four had two bands on a single arm, two had two bands on centromeric and terminal regions and 26 had single bands on a single arm. The 11 signals of the 5S and 45S rDNA sites and the the Arabidopsis-type telomere signals and DAPI bands performed variation in size and intensity