Physical Mapping of 5S rDNA, 18S rDNA and Telomere Sequences in Three Species of the Genus Artemisia (Asteraceae) with Distinct Basic Chromosome Numbers

Abstract

Fluorescence in situ hybridization (FISH) with both of 5S and 18S rDNAs, and Arabidopsis-type telomere sequences was carried out in 3 species of the genus Artemisia (Asteraceae) with different basic chromosome numbers, x=8, 9 and 17, to understand their chromosomal organization and evolution. Chromosomal distribution of telomere sequences, which was restricted only to the ends of all chromosomes, was reported here for the first time in this genus. Although 5S rRNA gene loci are generally localized independently of 45S rRNA gene loci in eukaryotic chromosomes, all of the 5S rDNA sites are the same number and co-localized with the 18S rDNA sites in the species investigated. We also discussed the chromosomal evolution of A. feddei (x=8) and A. princeps (x=17) having a derivative basic chromosome number in this genus.