© 1998 Heron Publishing—Victoria, Canada
Accumulation of flavonoids and related compounds in birch induced by UV-B irradiance
Anu Lavola (1)
1. Department of Biology, University of Joensuu, P.O. Box 111, SF-80101 Joensuu, Finland (lavola@joyl.joensuu.fi) / Received February 3, 1997
Summary
A growth chamber experiment was conducted to examine the effects of UV-B exposure (4.9 kJ m–2 day–1 of biologically effective UV-B, 280–320 nm) on shoot growth and secondary metabolite production in Betula pendula (Roth) and B. resinifera (Britt.) seedlings originating from environments in Finland, Germany and Alaska differing in solar UV-B radiation and climate.
Neither shoot growth nor the composition of secondary metabolites was affected by UV-B irradiance, but the treatment induced
significant changes in the amounts of individual secondary metabolites in leaves. Leaves of seedlings exposed to UV-B radiation
contained higher concentrations of several flavonoids, condensed tannins and some hydroxycinnamic acids than leaves of control
seedlings that received no UV-B radiation. At the population level, there was considerable variation in secondary metabolite
responses to UV-B radiation: among populations, the induced response was most prominent in Alaskan populations, which were
adapted to the lowest ambient UV-B radiation environment. I conclude that solar UV-B radiation plays an important role in
the formation of secondary chemical characteristics in birch trees.
Keywords:
Betula pendula, Betula resinifera, birch populations, phenolic acids, tannins, ultraviolet-B radiation.
