Polymorphism analysis of the ITS1-5.8S rDNA-ITS2 region of some peony species growing in the collection of the Botanical Garden of the Ural Branch of the Russian Academy of Sciences

Abstract

Representatives of the genus Paeonia (Paeonia L.) are economically and socially important ornamental plants. Moreover, some species are widely used in folk medicine. Various peony cultivars are prominent examples of active centuries-old plant breeding. They are commonly employed for soft landscaping of botanical gardens, urban landscapes, and household plots. With the development of molecular genetics, ornamental plant breeding received fresh impetus. Research has enabled the identification of markers that help to determine important ornamental and economic characteristics, such as the flower shape, leaf color, corolla color, degree of doubleness, and presence of fragrance. These advances accelerate the breeding process. Additionally, new cultivars can be certified quite accurately. Our article presents the results of the research aimed at testing the method of certification and verification of representatives of the genus Paeonia based on the variability in the ITS1-5.8S rDNA-ITS2 region. In the course of the analysis, we managed to identify the P. arientina species which had been included in the collection of the Botanical Garden of the Ural Branch of the RAS under a different taxonomic name (P. mascula). Additionally, we assessed the genetic diversity of the studied ribosomal DNA region, including the ITS1-5.8S rDNA-ITS2 sequences of several other species. Total DNA was isolated using the CTAB method. The consecutive sequences were evaluated using various programs (Mega6, Bioedit, DNAxp). The research has revealed that all peony species we studied are characterized by high variability in the region under investigation. The number of polymorphic sites was 155, and the total number of mutations amounted to 164. The number of sites with a single mutation was high (126). Haplotype diversity (Hd) for all species under study equaled 0.978±0.019. We verified the identity of the taxa included in the collection of the Botanical Garden of the Ural Branch of the Russian Academy of Sciences based on the analyzed ITS region of the ribosomal DNA. The article concludes that it is appropriate to use the ITS1-5.8S rDNA-ITS2 region when certifying species of the genus Paeonia to include them in the collections of Botanical Gardens as it is difficult to identify some peony species solely by their morphological characteristics.