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-methylaraneol. HPLC analysis showed that 20 days of UV-B radiation increased the synthesis of 7-O-methylaraneol 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 U V 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

Seasonal accumulation of ultraviolet‐B screening pigments in needles of Norway spruce (Picea abies (L.) Karst.)

“…Flavonoid and hydroxycinnamic acid metabolites usually accumulate in the central vacuoles of guard cells and epidermal cells as well as subepidermal cells of leaves (Weissenböck, Hedrich & Sachs 1986; Hutzler et al 1998) where they protect the inner cell layers from UV‐B damage (Landry, Chapple & Last 1995; Sheahan 1996). In addition, some compounds were found to be covalently linked to plant cell walls (Strack et al 1988; Schnitzler et al 1996), others occur in waxes (Schmutz et al 1994) or on external surfaces of plant organs (Cuadra & Harborne 1996; Chaves, Escudero & Gutierrez‐Merino 1997).…”

Nuclear Localization of Flavonoid Enzymes in Arabidopsis

“…In some tissues, such as the epidermis of leaves and flowers and endothelium of the developing seed coat, flavonoids are transported primarily to the vacuole by processes that appear to involve multidrug resistance-associated protein or multidrug and toxic compound extrusion proteins (14 -16). In other tissues, a significant proportion of flavonoids are deposited in the cell wall (17)(18)(19)(20) or secreted (21)(22)(23). Vesicles apparently involved in transport of flavonoids to the cell periphery have been described in sorghum plants responding to fungal infection (24) and in maize cells induced to accumulate anthocyanins (25).…”

Histochemical analysis of phenylphenalenone-related compounds in Xiphidium caeruleum (Haemodoraceae)

“…Phenolic compounds and their biosynthetic enzymes show a high degree of compartmentation within plants (Reinold and Hahlbrock 1997;Wink 1997). Furthermore, some compounds are localised in cell walls and on the surface of plant organs (Cuadra and Harborne 1996;Fernandez et al 1999;Karabourniotis et al 2001). Furthermore, some compounds are localised in cell walls and on the surface of plant organs (Cuadra and Harborne 1996;Fernandez et al 1999;Karabourniotis et al 2001).…”