Intragenomic Polymorphism of 35S rDNA Internal Transcribed Spacers: Verification of the Hypothesis on the Hybridogenic Origin of Tetraploid Pulsatilla vulgaris

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Elizaveta O. Punina¹, Alexander A. Gnutikov^1,2, Nikolay N. Nosov¹, Victoria S. Shneyer^1,a*, and Alexander V. Rodionov^1,3

¹Komarov Botanical Institute, Russian Academy of Sciences, 197022 St. Petersburg, Russia

²Vavilov All-Russian Institute of Plant Genetic Resources, 190000 St. Petersburg, Russia

³Faculty of Biology, St. Petersburg State University, 119034 St. Petersburg, Russia

^* To whom correspondence should be addressed.

Received: September 1, 2025; Revised: November 10, 2025; Accepted: November 20, 2025

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Pulsatilla vulgaris (pasque flower) is a rare and endangered plant species. Using ITS1-5.8S rDNA-ITS2 barcode sequencing and locus-specific NGS of the ITS1 spacer, we studied intraspecific and interspecific polymorphism of 35S rDNA loci and investigated the origin of tetraploid P. vulgaris from a unique Russian population. For the first time, the chromosome number in the karyotype of plants from this population was determined as 2n = 32. It was shown that one of the parental species of this tetraploid is the diploid Pulsatilla patens (2n = 16), while the identity of the second parental species remains unknown, although it appears to be closely related to the diploid Pulsatilla pratensis.

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KEY WORDS: ITS1, ITS2, rDNA, 35S rRNA genes, plant molecular phylogeny, Ranunculaceae, Pulsatilla, hybrids, locus-specific NGS (Illumina), allopolyploids

DOI: 10.1134/S0006297925602722

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