ISSN 1022-7954, Russian Journal of Genetics, 2017, Vol. 53, No. 2, pp. 202–212. © Pleiades Publishing, Inc., 2017.
Original Russian Text © E.O. Punina, E.M. Machs, E.E. Krapivskaya, A.V. Rodionov, 2017, published in Genetika, 2017, Vol. 53, No. 2, pp. 181–191.
Polymorphic Sites in Transcribed Spacers of 35S rRNA Genes
as an Indicator of Origin of the Paeonia Cultivars
E. O. Punina
*, E. M. Machs
, E. E. Krapivskaya
, and A. V. Rodionov
Komarov Botanical Institute, Russian Academy of Sciences, St. Petersburg, 197376 Russia
Biological Department, St. Petersburg State University, St. Petersburg, 199034 Russia
Received January 22, 2016
Abstract⎯Region ITS1–5.8S rDNA–ITS2 is sequenced in 27 varieties of cultivated ornamental peonies, ten
of which presumably originate from Paeonia lactiflora, one from P. o f f i c in ali s, 13 from hybridization of P. lac-
tiflora and P. pereg r i n a, or P. off i c i n a l is, and three are Itoh hybrids. Comparative analysis of distribution pat-
terns of polymorphic sites (PS) for the obtained DNA sequences and data from GenBank is carried out.
Hypotheses of origin of the studied varieties, except for two, which, as previously assumed, originate from
hybridization of P. lactiflora and P. p eregrina, are confirmed. It is shown that the sequence ITS1–5.8S
rDNA–ITS2 is a good genetic marker for cultivars of the P. lactiflora group and Itoh hybrids, and that the PS
distribution patterns in these sequences can provide valuable information on the kinship and origin of individual
varieties. However, insufficient knowledge of wild species from the P. o f f i c i n a l i s kinship group limits the use of
this marker in the study of varieties obtained through interspecific hybridization within the Paeonia section.
Keywords: Paeonia, peonies, variety, Itoh hybrids, interspecific hybridization, ITS1, ITS2, 5.8S rDNA
Acknowledged favorites of any garden, varietal
peonies are extremely diverse. In 2007, the number of
known varieties of peonies was 7995  and growing.
Peonies are an economically important cultivar. For
example, just the Dutch auction in 2009 sold 63 mil-
lion plants worth about $30 million . These are not
only popular ornamental plants but also a source of
valuable medicinal raw materials [3, etc.].
It is important to identify varieties when working
with peonies. Morphological descriptions of orna-
mental varieties are sometimes inaccurate; many vari-
eties are very similar in appearance, moreover, even
instances of the same variety planted in different con-
ditions may exhibit variability in color of flowers,
number of petals, etc. . When it comes to medicinal
raw materials, it can be necessary to identify already
harvested and dried rhizomes of peonies [3, etc.].
There are about 40 wild species of peonies around
the world, but only a few of them are involved in the
main breeding work. Most varieties have been bred by
selection and crossing of mutant forms of the species
Paeonia lactiflora, which in natural populations
demonstrates varying coloring, number of petals, etc.
A small part of the varieties, as is commonly believed,
originate from P. off i cin a l is or its related species. There
is also a group of varieties of hybrid origin: one parent
is usually indicated as P. lactiflora and the other as
P. of f ici n a li s or P. peregrina. Less common are varieties
derived from crosses of other species of the Paeonia
section. Widespread are ornamental varieties of
shrubby peonies, the majority of which are species and
hybrids within the Moutan section. A special place is
occupied by recently developed varieties bred through
intersectional hybridization, the so-called Itoh
hybrids, which are obtained by crossing varieties of
herbaceous P. lactiflora (Paeonia section) and varieties
of shrubby species (Moutan section).
Different sources may specify the origin of Paeonia
cultivars in different ways, and in some cases, the history
of creating varieties may be lost completely, especially if a
cultivar is old. Moreover, even the existing descriptions of
the history of creating varieties are subject to varying
interpretations, since many wild species of peonies have a
large number of synonyms, misleading the breeders and
gardeners. Hence, there is the need to find species- and
variety-specific genetic markers, and one of these mark-
ers could be sequences of transcribed spacers ITS1 and
ITS2 in the 35S rRNA gene
In the nuclear genome of higher plants, the sequences encoding
18S, 5.8S, and 26S rRNA are organized as a single transcrip-
tional unit about 6–10 kb in length. By analogy with rRNA
genes of mammals, this gene is often referred to as the 45S
rRNA gene (for example, in [30, 31]), but in fact the molecular
weight of the pre-rRNA transcript in plants is significantly
less—approximately 35–36S [32, 33]; therefore, it is more cor-
rect to call this gene the 35S rRNA gene [34, 35].