Flavonoid glycoside variation in wild specimens of Centaurea montana (Compositae)

Abstract

Individuals of Centaurea montana (Compositae) originating from two types of alpine plant community—tall grass prairies under Larix (Adenostylion) and high-altitude manured meadows (Triseto—Polygonion)-were investigated for their flavonoid glycoside patterns. These specimens displayed complex polyphenolic patterns (up to 30 compounds in the 2D chromatograms of some specimens) with considerable diversity in the distribution of molecules (in total, 48 glycosides were detected). Two “extreme” chemotypes were detected: “complex” C- glycosides (i.e. a mixture of acylated, O- conjugated 6-C- glucosides , mainly based on apigenin, luteolin and chrysoeriol) vs O- glycosides (mainly 7- and 4′-monosides of apigenin and luteolin). Many other chemotypes were also displayed, corresponding to different assemblages of molecules of these two types with 6-C- mono-glycoflavones flavones di-O- glycosides and some other compounds. Consistent results revealing the existence of natural diversity in C. montana flavonoids were obtained with individuals from three different geographic sources. Repeated analyses of individuals from the different stations and grown in culture rooms under controlled conditions show that the flavonoid fingerprint is stable and not affected by external factors and consequently that the natural diversity in this species rests upon genetic parameters. This diversity originates in the strictly allogamous reproductive mode of C. montana controlled by a dominance/co-dominance sporophytic incompatibility system and can be held and spread in stations by an intense asexual multiplication. Regarding the relationships between the flavonoid profiles and the phytosociological origin of individuals, those with C- glycosidic patterns (all types) were more frequent (about three-quarters of the collected samples) in meadows while in tall grass prairies a comparable proportion of individuals displayed O- glycosidic patterns.