Taxonomic Study of Korean Chrysanthemum based on Morphological, Molecular, and Chemotaxonomical Characteristics

Abstract

Korean Chrysanthemum is Korean native plant known as Korean wild chrysanthemum, which is very useful genetic resource for landscaping or medicinal plant. Taxonomic relationships among Korean Chrysanthemum were investigated using principal component analysis (PCA) and cluster analysis (CA) which were conducted by grouping the taxa based on the morphological, molecular, and chemotaxonomic data. Korean Chrysanthemum was collected from natural habitats in different regions of Korean Peninsula from 2006 to 2009. Plants were grown in the greenhouse at the Highland Agricultural Research Center of National Institute of Crop Science, Rural Development Administration (Pyeongchang, Gangwon, Korea), from 2006 to 2014. The aim of this study was to obtain clear morphological classification within Korean Chrysanthemum using PCA and cluster analysis by comparing 35 horticultural qualitative and quantitative morphological characteristics. As a result, the shape, length, and L/W ratio in leaf were the most remarkable morphological characteristics for the classification, which varied significant differences among 15 Chrysanthemum taxa. Group I included C. zawadskii subspecies, which had great potential as ground cover material with dense branches (average 18.5 cm in length) and simultaneous flowering with longer flowering period of white or pink flowers. C. zawadskii ssp. acutilobum var. alpinum in Group I also showed potential as useful breeding species for the regulation of various flowering periods due to its spring flowering time while the other taxa bloomed in autumn. Group II had only one species, C. lineare, which had unique pale yellow and cone-shaped seed. The seed length of C. lineare was 3.2 mm and it was longer than the other groups. C. lineare had exceptionally longer leaves with no petiole in both basal and cauline leaves. Group III included three C. indicum subspecies, C. boreale, and C. makinoi. Taxa in Group III were mostly bushy plants with lignified stems at flowering time. The diameter of flower head ranged from 15.1 to 27.3 mm, relatively smaller than the other groups (Groups I and II). Group III seemed to be desirable species as edible medicinal plants for flower tea or cosmetics because of their small flower heads (15.1-27.3 mm in diameter) and more numbers of flowers (80-223 ea) with white or yellow petals. Phylogenetic studies were conducted to evaluate interspecific relationships among Korean Chrysanthemum taxa using internal transcribed spacer (ITS 1, ITS 2) region sequences of nuclear ribosomal DNA (nrDNA) and chromosome complement. The taxa had well-developed series of polyploids (4x, 6x, 8x) from diploids (2n=2x=18) with basic chromosome number (n=9). The divergence rate was very low within C. zawadskii subspecies ranging from 0.0 to 1.5%. C. lineare was basally branched within Chrysanthemum. Our results suggested that ITS region sequences were not effective for morphological classification of Chrysanthemum, such as C. zawadskii and C. indicum subspecies. Final study was conducted to reveal taxonomic relationships between the taxa through chemical classification by analyzing flavonoids and volatile flavor compounds. As a result, five flavonoids were identified from Chrysanthemum using HPLC/MS: luteolin 7-O-rutinoside, luteolin-7-O-glucoside, apigenin-7-O-glucoside, apigenin, and acacetin-7-O-rutinoside. In particular, C. zawadskii ssp. acutilobum, ssp. yezoense, ssp. latilobum, and C. indicum var. acuta, which showed effective anti-inflammatory activities, and had four flavonoids (luteolin-7-O-rutinoside, luteolin-7-O-glucosede, apigenin-7-O-glucoside, and acacetin-7-O-rutinoside), indicating that these four taxa would be used as functional materials. In addition, in 15 taxa from GC/MS analysis, 45 volatile flavor compounds were detected. Camphor, borneol, phytol, phytol, α-pinene, camphene, 1,8-cineole, and germacrene-D were main volatile compounds in Chrysanthemum, with differences of significant content among the taxa. Camphor, which is known for its antimicrobial properties, was the most abundant volatile compound in C. zawadskii ssp. latilobum and var. leiophyllum. In particular, C. indicum subspecies and C. boreale contained α-thujone, which has outstanding anti-bacterial, anti-cancer, anti-inflammatory, and anti-diabetic efficacies. Especially, C. indicum var. albescens could be used as perfumes since it showed twenty one times more camphene content than C. indicum. In addition, C. indicum var. acuta contained fairly high content of 1,8-cineole. Therefore, the present study will provide the basic materials needed for species selection and cultivation of Chrysanthemum species, which are useful in food, cosmetic, and medicin industry.