Changes in epicuticular flavonoids and photosynthetic pigments as a plant response to UV-B radiation

Abstract

Treatment of Gnaphalium vira-vira plants with UV-B radiation caused changes in plant growth and in plant chemistry. The leaf surface contained two O-methylated flavones, araneol and 7-O-methylarancol. HPLC analysis showed that 20 days of UV-B radiation increased the synthesis of 7-O- methylarancol at the expense of araneol. Spectrophotometric analysis of the photosynthetic pigments showed that UV-B radiation also increases the pigment content in treated plants. Another UV alteration is epidermal hair damage, as observed in SEM pictures of treated leaves. This combination of physiological and phytochemical effects may be interpreted as a plant response to UV-B stress.