Interstitial Telomere-like Repeats in the Haplopappus gracilis (Asteraceae) Genome Revealed by Fluorescence in situ Hybridization

Abstract

Fluorescence in situ hybridization (FISH) using an Arabidopsis-type telomeric sequence (TTTAGGG)_n probe to the mitotic chromosomes of Haplopappus gracilis (n=2) revealed the presence of Interstitial Telomere-like Repeats (ITRs) in at the subdistal position of the long arm of both chromosome pairs (1g and 2g). The H. gracilis genome (n=2) is generally thought to reconstitute from the n=4 complement of the allied species, H. ravenii. The sites we identified by FISH are in close proximity to the chromosomal rearrangement fusion points. This evidence supports the hypothesis that the karyotype of H. garacilis evolved from that of H. ravenii due to chromosome breakage and the subsequent end-to-end chromosome fusion.