FISH physical mapping of 5S, 45S and Arabidopsis-type telomere sequence repeats in Chrysanthemum zawadskii showing intra-chromosomal variation and complexity in nature

Abstract

Chrysanthemum zawadskii showed 2n=54 (hexaploid chromosme number) and extensive variation in the color of the ligules (from white to pinkish). FISH yellow colored signals of the 5S, 45S rDNA and telomeres were obtained after hybridized of the biotin labeled of the 5S rDNA, pTa71 and telomeric sequence repeats probes to somatic chromosomes. They showed 5-6 interstitial and two terminal signals at the 5S rDNA region, 10-14 terminal and 4-5 interstitial signals at the 45S rDNA region and the telomeric signals at the region of telomeric sequence repeats on both chromosome arms in the chromosome complement. Bicolor FISH showed that co-localization of the 5S and 45S rDNA on two terminal and five interstitial loci. This phenomenon might indicate a natural hybridization with closely related genera and/or genome rearrangement.