There are about 40 species of Polygonatum in the world, mainly distributed in the northern temperate zone, and distributed in Europe, Asia, North America and other regions. China has more than 30 species of Polygonatum(Editorial Committee of Flora of China 2000), which is the distribution center of Polygonatum. Polygonatum cyrtonema Hua is a perennial herb of the Polygonatum in the Liliaceae family and is one of the three medicinal Polygonatum Rhizoma stipulated in the "Pharmacopoeia of the People's Republic of China" (Chinese Pharmacopoeia Commission. 2020). P· cyrtonema has been used as medicine in China for more than 2,000 years and is a traditional medicinal herbal medicine with food. In addition to its medicinal values such as anti-aging, immune modulation, blood lipid regulation, memory improvement, anti-tumor, and antibacterial(Zhao 2005, Wu 2014, Huang 2016, Li 2018, Yang 2018, Li 2019, Ma 2019, Fan ZW 2020), P· cyrtonema also has broad prospects for development in food and health products.
P· cyrtonema is distributed in all provinces of the Yangtze River basin in China, of which Anhui is one of its main production areas. According to the "Flora of Anhui" (Group 1992), P· cyrtonema is distributed in Qimen County, Shitai County, Xiuning County,, Tongling City, and Jinzhai County, which can be divided into two major regions, Dabie Mountain and South Anhui Mountain.
Previous studies on the germplasm resources and plant morphological characteristics of P· cyrtonema (Cheng 2021)revealed that there were obvious differences in plant organs such as rhizomes, leaves and pedicels between Dabie and South Anhui Mountainous areas. Based on the differences in plant morphology and distribution areas, P· cyrtonema can be divided into three major taxa. In the Dabie Mountain area (JZ population) the plants are tall overall, with long total pedicels, often more than twice as long as the pedicels, the rhizomes are often cylindrical or ginger-shaped, with larger stem scars, often accounting for more than half of the rhizomes, and more winged buds. The plants in the mountainous areas of southern Anhui (QY population and JD population) are small compared with the JZ population, and the rhizomes are checkerboard-shaped. The QY population plants have smaller stem scars and the JD population plants have more than two to three shoots per year on the rootstock. Further studies on the fitness zones and ecological factors of P· cyrtonema revealed that both Dabie and South Anhui Mountains are highly suitable zones for P· cyrtonema, and the dominant ecological factors causing differences in plant morphology between the two regions are eight factors such as precipitation in February and March, soil type, vegetation type, and slope orientation.
In the study of diversity of plant morphological characters, phenotypic polymorphism is often low, and the accuracy of plant clustering by this means needs to be improved. Therefore, the application of DNA molecular marker technology in the study of genetic diversity of germplasm resources is becoming more and more common, among which ISSR molecular markers and SSR molecular markers are more widely used. Compared with ISSR, SSR has strong specificity and high polymorphism for closely related species, which is suitable for genetic diversity among closely related populations (Li 2005, Zhu 2018, Ji 2020). SSR molecular markers have the advantages of high polymorphism, co-dominant inheritance, simple and rapid technique, and good reproducibility. More importantly, SSR marker technology is not restrictive to the developmental period and organs of plant materials, which makes it easier to study the kinship of species at the molecular level, conserve germplasm resources, construct mapping and assist breeding. Currently, SSR molecular markers have been widely used in the study of genetic diversity, classification, evolutionary origin, fingerprinting and genetic map construction of plant resource(Liu 2010, Feng 2016, Wang 2018, Getaneh 2021, Feng PL 2022, Li 2022, Mao 2022).
In this study, based on the previous study on the diversity of morphological characters of P· cyrtonema plants in different regions, 96 P· cyrtonema germplasm resources from seven regions were analyzed for genetic diversity using SSR molecular marker technology to elucidate the kinship and population genetic structure of P· cyrtonema germplasm resources from different sources and to evaluate the diversity of P· cyrtonema germplasm resources. In addition, new germplasm has greater disadvantages in both breeding and resistance to pests and diseases because of the lack of gene flow between species due to directed breeding of new germplasm and the increasingly narrow genetic background. In this study, modern molecular biology techniques were used to study the genetic diversity of the crop, with a view to having important theoretical and practical significance for the resource management and conservation of P· cyrtonema germplasm and molecular marker-assisted breeding.