Journal Article

Effects of solar UV-A and UV-B radiation on gene expression and phenolic accumulation in <i>Betula pendula</i> leaves

Luis O. Morales, Riitta Tegelberg, Mikael Brosché, Markku Keinänen, Anders Lindfors and Pedro J. Aphalo

in Tree Physiology

Volume 30, issue 7, pages 923-934
Published in print July 2010 | ISSN: 0829-318X
Published online June 2010 | e-ISSN: 1758-4469 | DOI: http://dx.doi.org/10.1093/treephys/tpq051
Effects of solar UV-A and UV-B radiation on gene expression and phenolic accumulation in Betula pendula leaves

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Ultraviolet (UV) radiation is an important environmental factor for plant communities; however, plant responses to solar UV are not fully understood. Here, we report differential effects of solar UV-A and UV-B radiation on the expression of flavonoid pathway genes and phenolic accumulation in leaves of Betula pendula Roth (silver birch) seedlings grown outdoors. Plants were exposed for 30 days to six UV treatments created using three types of plastic film. Epidermal flavonoids measured in vivo decreased when UV-B was excluded. In addition, the concentrations of six flavonoids determined by high-performance liquid chromatography-mass spectrometry declined linearly with UV-B exclusion, and transcripts of PAL and HYH measured by quantitative real-time polymerase chain reaction were expressed at lower levels. UV-A linearly regulated the accumulation of quercetin-3-galactoside and quercetin-3-arabinopyranoside and had a quadratic effect on HYH expression. Furthermore, there were strong positive correlations between PAL expression and accumulation of four flavonols under the UV treatments. Our findings in silver birch contribute to a more detailed understanding of plant responses to solar UV radiation at both molecular and metabolite levels.

Keywords: chlorogenic acids; flavonoids; relative transcript accumulation; silver birch; solar UV exclusion; transcription factors

Journal Article.  8113 words.  Illustrated.

Subjects: Plant Sciences and Forestry

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