Integration of Repeatome and Cytogenetic Data on Tandem DNAs in a Medicinal Plant Polemonium caeruleum L

Polemonium caeruleum L. (Polemoniaceae) is a perennial flowering plant native to Eurasia and North America, which is used as a fodder, medicinal, and ornamental plant. Many issues related to the taxonomy and origin of this valuable species still remain unclear. The intraspecific genetic variability of P. caeruleum and chromosomal organization of its genome are insufficiently studied. For the first time, we analyzed NGS genomic data of P. caeruleum using ReapeatExplorer2/TAREAN/DANTE Pipelines. In its repeatome, we identified 66.08% of Class I retrotransposons; 0.57% of Class II transposons; 0.42% of ribosomal DNA; and 0.87% of satellite DNA (six high-confident and three low-confident putative satellite DNAs). FISH chromosome mapping of seven tandem DNAs was carried out in two P. caeruleum varieties and two wild populations. Our results demonstrated the effectiveness of using satDNAs Pol_C 46 and Pol_C 33 in combination with 45S rDNA and 5S rDNA for precise chromosome identification. This approach allowed us to study intraspecific chromosomal variability and detect chromosomal rearrangements in the studied accessions of P. caeruleum, which could be related to the speciation process. These novel molecular markers are important for chromosome studies within Polemonium to clarify its taxonomy and phylogeny, and also, they expand the potential of different breeding programs.