PHOTOPROTECTIVE ROLE OF ANTHOCYANINS REGULATING PSII ACTIVITY OF SETCREASEA PALLIDA EXPOSED TO EXCESSIVE LIGHT ENERGY

摘要

The appearance of red, purple or blue colors in leaf tissues is due to anthocyanins synthesis induced when plants are exposed to various environmental stresses such as excess of light energy, UV radiations, low temperature, osmotic shock or drought (Chalker-Scott 1999). Anthocyanins belong to the water-soluble phenolic compounds associated with flavonoids known to have heterogeneity forms in plants (Iwashina 2000). These pigments are suited within anthocyanoplast, or ganelle located in vacuoles of leaf epidermis cells (Pecket & Small 1980). Anthocyanins biosynthesis in different plant species have been intensively investigated (Stafford 1990, Sponga et al 1986, Mancinelli 1985), although questions what are their functional role and mechanism of action stay to be further explained. Therefore, question posed few years ago by Gould et al (Nature 1995) why plants synthesize these non-photosynthetic pigments and what is their role in leaves remained to be considered again. In the past, different interpretations have been proposed concerning the anthocyanins protective role for plants exposed to environmental stress conditions (see review Chalker-Scott 1999). For now, one of the most upstanding believes concerning anthocyanin roles was based on its photoprotection of photosynthetic activity when plants are exposed to excess radiation (Smillie & Hetherington 1999). However, the significance of this explanation may require further investigation since mechanistic model was not still elucidated. We present here the experimental evidence for anthocyanin as a non-photosynthetic pigment to have important regulatory role for PSII photochemistry in plants exposed to strong light intensity.