A telomere is the region of DNA that marks the end of a chromosome. The protect the ends of the chromosome, and stop one chromosome from fusing with another. So finding something that looks like a telomere in the middle of a chromosome would be odd – but it happens. And no one knows exactly why.
Although interstitial occurrence of telomeric repeat motifs (ITR) has been reported in the genome of a few organisms, the striking level of polymorphism found by Rosata et al. within a single species has not been described before. Rosata and colleagues investigate whether a comparable pattern of dynamism found for another repetitive element, interstitial 45S rDNA sites, in the genus Anacyclus (Asteracea), is linked to ICT and both have the same underlying causes.
![Cariograms showing inter- and intrapopulation site number variation of interstitial telomeric repeats (ITRs) in Anacyclus clavatus.](https://i0.wp.com/botany.one/wp-content/uploads/2018/09/mcy079_cariogram.jpg?resize=770%2C578&ssl=1)
This study provides hints that ancient Robertsonian translocations or the amplification of terminal 45S rDNA sites can be involved in the patterns found for both repetitive families, although a wide survey across Asteraceae is needed for a conclusive answer.
While the regions studied are tiny, the effects could be big if you use ITRs to examine plant evolution. The authors say: “Our results suggest caution for those studies using ITRs as markers of species’ phylogenetic relationships without a thorough sampling.”