Satellite DNA and transposable elements in seabuckthorn (Hippophae rhamnoides), a dioecious plant with small Y and large X chromosomes

Puterova, J., Razumova, O., Martinek, T., Alexandrov, O., Divashuk, M., Kubat, Z., Hobza, R., Karlov, G., Kejnovsky, E.
GENOME BIOLOGY AND EVOLUTION 9: 197-212, 2017

Keywords: sex chromosomes, genome composition, chromosomal localization, repetitive DNA
Abstract: Seabuckthorn (Hippophae rhamnoides) is a dioecious shrub commonly used in the pharmaceutical, cosmetic, and environmental industry as a source of oil, minerals and vitamins. In this study,weanalyzed the transposable elements and satellites in its genome.We carried out Illumina DNA sequencing and reconstructed the main repetitive DNA sequences. For data analysis, we developed a new bioinformatics approach for advanced satelliteDNAanalysis andshowedthat about25%of thegenomeconsists of satelliteDNAand about 24% is formed of transposable elements, dominated by Ty3/Gypsy and Ty1/Copia LTR retrotransposons. FISH mapping revealed X chromosome-accumulated, Y chromosome-specific or both sex chromosomes-accumulated satellites butmost satellites were found on autosomes. Transposable elements were locatedmostly in the subtelomeres of all chromosomes. The 5S rDNA and 45S rDNA were localized on one autosomal locus each. Although we demonstrated the small size of the Y chromosome of the seabuckthorn and accumulated satellite DNA there, we were unable to estimate the age and extent of the Y chromosome degeneration. Analysis of dioecious relatives such as Shepherdia would shed more light on the evolution of these sex chromosomes.
DOI: 10.1093/gbe/evw303
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IEB authors: Roman Hobza