Celine, a LINE retrotransposon colonized in the centromeres of poplar chromosomes
Centromeres in most higher eukaryotes are composed of long arrays of repetitive DNA sequences. One of the most distinct centromeric repeats is the centromeric LTR retrotransposon CRM reported in plants. Here we report a centromeric long interspersed nuclear element (LINE), Celine, in Populus species. High-resolution cytological mapping using pachytene and fiber-FISH showed that Celine has colonized preferentially in the CENH3-associated functional centromeres of every poplar chromosome. Interestingly, 74% of the Celine elements localized in the CENH3-binding domains, by contrast, only 44% of the CRM elements were bound to CENH3 domains. These results suggest different centromere targeting mechanisms employed by Celine and CRM elements. We identified Celine-like LINE elements in tea plant Camellia sinensis and green ash tree Fraxinus pennsylvanica, both woody species. The centromeric localization of these Celine-like LINEs was confirmed in both species. Thus, the centromeric specificity of Celine-like LINEs is conserved among distantly related plant species.