| description |
Seabuckthorn (Hippophae rhamnoides) is a dioecious shrub traditionally used in the pharmaceutical, cosmetic and environmental industry as a source of oil, minerals and vitamins. The first cytogenetic studies on the seabuckthorn demonstrated either a small or large Y chromosome and information on the seabuckthorn genome is lacking. We performed Illumina DNA sequencing and reconstructed the main repetitive DNA sequences. For data analysis, we have developed a new bioinformatic approach for advanced satellite DNA analysis. We showed that about 25% of genome is represented by satellite DNA and about 24% is formed of transposable elements, dominated by Ty3/Gypsy and Ty1/Copia LTR retrotransposons. Our FISH mapping revealed X chromosome-specific, Y chromosome-specific or both sex chromosomes-specific satellites but most satellites were present on autosomes. Transposable elements were present mostly in the subtelomeres of all chromosomes. The 5S rDNA and 45S rDNA were localized on one autosomal locus each. The small size of the Y chromosome and gathering of satellite DNA there, indicate that the Y chromosome of H. rhamnoides is in a later stage of evolution but an analysis of dioecious relatives like Shepherdia would shed more light on the age of these sex chromosomes. |