ULTRAVIOLET-B (280-320 NM) ABSORBING PIGMENTS IN THE LEAVES OF SILENEVULGARIS - THEIR ROLE IN UV-B TOLERANCE

The UV-B radiation tolerant perennial herb Silene vulgaris was tested on the influence of incident UV-B fluxes during growth on the synthesi s of UV-B absorbing pigments in the leaves. Analysis of methanolic lea f extracts showed a stimulating effect of UV-B on the absorbing abilit y of leaf extracts. HPLC analysis made clear that UV-B radiation stimu lated extractable flavonoid concentrations in leaves, but that UV-B ab sorption could only be partly attributed to these flavonoids. The cont ribution of flavonoids to UV-B absorption diminishes if plants mature. Other possible functions of flavonoids in plants growing under elevat ed UV-B conditions are discussed.