1 | INTRODUCTION
Polygonatum Mill. is the largest genus in the Polygonateae tribe.Polygonatum Mill. comprises 70 species widely distributed across
the temperate Northern Hemisphere (Gong et al., 2023). Of these, 37
species and one variety had records of medicinal use and the rhizome was
the most commonly used part of the plant. Many Polygonatum plants
are highly effective in treatment age-related diseases, diabetes, lung
diseases, coughs, fatigue, and feebleness in clinical practice (Zhao et
al., 2018). Polygonatum kingianum , P. sibiricum ,P. cyrtonema and P. odoratum contain various active
ingredients, such as polysaccharides, steroidal saponins, and alkaloids
which are collected from the Chinese Pharmacopoeia as the official
source of Polygonati rhizoma and Polygonate odorati rhizome (Luo et al.,
2022). Polysaccharides from P. filipes and P.
zanlanscianense , as recorded by provincial standards, can significantly
inhibit the formation of intermediate diabetes products (Zhao et al.,
2020).Polygonatum is a diverse and widely distributed plant.Flora of China records that it is distributed in many provinces
of China, including Heilongjiang, Jilin, Liaoning, Hebei, Shanxi,
Shaanxi, Nei Mongol, Ningxia, Gansu, Henan, Shandong, Anhui, Zhejiang,
and Sichuan. Among them, P. cyrtonema is mainly distributed in
the Yangtze River Basin, whereas P. kingianum occurs in
southwestern China (Guo et al., 2022). In addition, the presence of
multiple medicinal plants of Polygonatum make it difficult to
identify. The phyllotaxis is usually an important basis for
distinguishing Polygonatum plants (Xia et al., 2022), which can
be mainly classified into alternate leaf types and verticillate leaf
types according to the phyllotaxis characteristics; for example,P. cyrtonema , P. filipes , and P. odoratum are
alternate leaf types and P. sibiricum , P. kingianum , andP. zanlanscianense are verticillate leaf types. The rhizome
morphology of Polygonatum plants is also diverse, with P.
sibiricum having a “Jitou-type” and an atypical “Jitou-type”.P. cyrtonema have three types, “Jiang-type”, “Cylinder-type”,
and “Baiji-type”, with variations in the composition of the rhizomes
of the different types (Hu et al., 2022). The indiscriminate use of
different species may cause crucial effects on the patient. Therefore,
establishing an effective identification method to distinguish between
the medicinal species of Polygonatum , is necessary.
DNA barcoding and molecular markers have been used for accurate species
delimitation and phylogenetic relationship inference inPolygonatum (Jiao et al., 2018; Lee et al., 2021). However,
species identification using traditional DNA barcoding techniques is
limited and does not allow for the accurate identification of closely
related species (Newmaster et al., 2008). The chloroplast genome
sequence has been proposed as a superbarcode for species authentication
(Li et al., 2015). The chloroplast genomes of medicinal plants such asAtractylodes (Wang et al., 2021), Gentiana (Zhao et al.,
2022), Peucedanum (Sun et al., 2023) and Tripterygium (Xu
et al., 2024) have been studied one after another and their intragenus
evolutionary relationships have been explored. Studies of the
chloroplast genomes of Polygonatum spp. have also been reported.
The genus Polygonatum is a monophyletic group comprising three
sections (sect. Sibirica , sect. Polygonatum , andsect. Verticillata ) (Xia et al., 2022).Heteropolygonatum , Disporopsis , Maianthemum , andDisporum are sister groups to Polygonatum within
Polygonateae (Wang et al., 2022). During the long evolutionary process
of the genus, the leaf type of this group evolved from verticillate
leaves to alternate leaves. The construction of a phylogenetic tree
based on the chloroplast genome showed that P. kingianum can be
clearly distinguished from other species in the verticillate leaf group,
providing a reliable means for the accurate identification of P.
kingianum (Shi et al., 2023). However, these studies did not focus on
sequencing or analyzing the chloroplast genomes of medicinal plants of
the genus Polygonatum .
Consequently, we sequenced and analyzed the whole chloroplast genomes of
six medicinal species of Polygonatum to enrich the understanding
of genome characteristics, screen mutational hotspots, and SSRs for
authentication of Polygonatum medicinal plants and elucidate the
phylogenetic relationship of Polygonatum medicinal plants.