Temperature is the key to altitudinal variation of phenolics in Arnica montana L. cv. ARBO

Abstract

Plants in alpine habitats are exposed to many environmental stresses, in particular temperature and radiation extremes. Recent field experiments on Arnica montana L. cv. ARBO indicated pronounced altitudinal variation in plant phenolics. Ortho-diphenolics increased with altitude compared to other phenolic compounds, resulting in an increase in antioxidative capacity of the tissues involved. Factors causing these variations were investigated by climate chamber (CC) experiments focusing on temperature and ultraviolet (UV)-B radiation. Plants of A. montana L. cv. ARBO were grown in CCs under realistic climatic and radiation regimes. Key factors temperature and UV-B radiation were altered between different groups of plants. Subsequently, flowering heads were analyzed by HPLC for their contents of flavonoids and caffeic acid derivatives. Surprisingly, increased UV-B radiation did not trigger any change in phenolic metabolites in Arnica. In contrast, a pronounced increase in the ratio of B-ring ortho-diphenolic (quercetin) compared to B-ring monophenolic (kaempferol) flavonols resulted from a decrease in temperature by 5 degrees C in the applied climate regime. In conclusion, enhanced UV-B radiation is probably not the key factor triggering shifts in the phenolic composition in Arnica grown at higher altitudes but rather temperature, which decreases with altitude.

Impact of Elevated Levels of Atmospheric CO2 and Herbivory on Flavonoids of Soybean (Glycine max Linnaeus)

“…Similar shifts in the quercetin:kaempferol ratio have been observed in plants grown under temperature stress (Albert et al 2009). Quercetin has a higher quenching capability than kaempferol (Rice-Evans et al 1996), and it was theorized that under temperature stress more quercetin was produced because of this quenching ability (Albert et al 2009). Similar effects may occur in soybeans growing under (Piubelli et al 2005).…”

Content of phenolic compounds in wild populations ofEpilobium angustifoliumgrowing at different altitudes

“…The amounts of flavonoids and caffeic ester derivatives generally increased with these environmental parameters. Especially, the impact of temperature seems to be of importance which is supported by results from climate chamber experiments performed in the group of C. Zidorn (Albert et al, 2009) who identified low temperature as a key factor for the accumulation of phenolic compounds in alpine plants.…”

Seasonal variation of the major secondary metabolites present in the extract of Eremanthus mattogrossensis Less (Asteraceae: Vernonieae) leaves

“…18 For Arnica montana for example, temperature is the key factor on the alterations of the phenolic compounds in higher altitudes. 19 Another example is the case of Brassica oleracea, that high levels of UV radiation led to increase the concentration of flavonoids, however the changes induced by UV did not alter the capacity to attract herbivore insects. 20 In the present work, we could not explain exactly the factors that are responsible for the correlation between the caffeoylquinic acids and flavonoids higher concentrations and the rainy season.…”