Taxonomic Study on Polygonatum cyrtonema Complex (Asparagaceae) revealed by morphological and molecular evidence


Correct species delimitation is the premise of biological and evolution research, biodiversity conservation, germplasm resource evaluation, and sustainable utilization. Polygonatum cyrtonema Hua is one of the three original species of traditional Chinese medicine (Huangjing). Its rhizome is rich in flavonoids, olysaccharides, fructooligosaccharides, steroids, triterpene saponins, and other nutritional and functional ingredients. The evidence, however, shows that P. cyrtonema was not a natural independent species but a species complex. Therefore, based on the extensive analysis of specimens (including type specimens), compared with its related species (such as P. filipes, P. langyanese, and P. odoratum), we present multiple evidences to clarify the classification problem of P. cyrtonema complex. Based on morphological characteristics and flowering period, the P. cyrtonema complex can be divided into four groups.
A substantial variation in qualitative and quantitative characteristics of macromorphological and micromorphological features was observed using light microscopy (LM) and scanning electron microscopy (SEM). The phylogenetic tree constructed by the ribosome sequences (6237bp) assembled by next-generation sequencing technology showed that four morphological groups were clustered into four monophyletic groups with high support. Additionally, the phylogenetic tree constructed based on nuclear primers and plastid genome also showed that these different groups were clustered into separate clades. Due to the limitations of materials, we selected two groups, which have the closest relationship and have been widely cultivated, for comparative analyses of the main chemical components. The ethanol extract was separated and purified by high performance liquid chromatography, and it was observed that there were clear differences among these groups. Thus, different types of P. cyrtonema complex have already shown such obvious differences, suggesting that they may have differentiated into different species. Based on the above research results, combined with the textual research of the specimens, the Polygonatum cyrtonema complex should be treated as four independent species: Polygonatum cyrtonema Hua, Polygonatum gutianshanicum (X.F. Jin) M. Ali. (comb. nov), Polygonatum jinzhaiense D.C.Zhang & J.Z.Shao and Polygonatum praecox M. Ali (sp. nov.).

Speaker: Dr. Maroof Ali

Affiliation: XTBG

Time: 4:30 PM, Tuesday, Sep. 13, 2022

Venue: ZOOM 会议平台 会议 ID:312 430 8960 会议密码 PWD:666666 

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