PAR modulation of the UV-dependent levels of flavonoid metabolites in Arabidopsis thaliana (L.) Heynh. leaf rosettes: cumulative effects after a whole vegetative growth period

• Published in: Protoplasma 2010-07, Vol.243 (1-4), p.95-103
• Main Authors: Götz, Michael, Albert, Andreas, Stich, Susanne, Heller, Werner, Scherb, Hagen, Krins, Andreas, Langebartels, Christian, Seidlitz, Harald K., Ernst, Dieter
• Format: Article
• Language: English
• Subjects: Arabidopsis - anatomy & histology; Arabidopsis - growth & development; Arabidopsis - radiation effects; Biomedical and Life Sciences; Cell Biology; Flavonoids - metabolism; Flowers & plants; Kaempferols - metabolism; Life Sciences; Original Article; Photosynthesis - radiation effects; Plant Leaves - growth & development; Plant Leaves - metabolism; Plant Leaves - radiation effects; Plant Sciences; Time; Ultraviolet radiation; Ultraviolet Rays; Zoology
• ISSN: 0033-183X; 1615-6102
• DOI: 10.1007/s00709-009-0064-5

Long-term effects of ultraviolet (UV) radiation on flavonoid biosynthesis were investigated in Arabidopsis thaliana using the sun simulators of the Helmholtz Zentrum München. The plants, which are widely used as a model system, were grown (1) at high photosynthetically active radiation (PAR; 1,310 µmol m −2  s −1 ) and high biologically effective UV irradiation (UV-B BE 180 mW m −2 ) during a whole vegetative growth period. Under this irradiation regime, the levels of quercetin products were distinctively elevated with increasing UV-B irradiance. (2) Cultivation at high PAR (1,270 µmol m −2  s −1 ) and low UV-B (UV-B BE 25 mW m −2 ) resulted in somewhat lower levels of quercetin products compared to the high-UV-B BE conditions, and only a slight increase with increasing UV-B irradiance was observed. On the other hand, when the plants were grown (3) at low PAR (540 µmol m −2  s −1 ) and high UV-B (UV-B BE 180 mW m −2 ), the accumulation of quercetin products strongly increased from very low levels with increasing amounts of UV-B but the accumulation of kaempferol derivatives and sinapoyl glucose was less pronounced. We conclude (4) that the accumulation of quercetin products triggered by PAR leads to a basic UV protection that is further increased by UV-B radiation. Based on our data, (5) a combined effect of PAR and different spectral sections of UV radiation is satisfactorily described by a biological weighting function, which again emphasizes the additional role of UV-A (315–400 nm) in UV action on A. thaliana .