Effects of solar UV-A and UV-B radiation on gene expression and phenolic accumulation in Betula pendula leaves.
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.
Department of Biosciences, Division of Plant Biology, PO Box 65 (Biocenter 3, Viikinkaari 1), FIN-00014, University of Helsinki, Helsinki, Finland. luis.morales@helsinki.fi
Luis O
LO
Morales
Riitta
R
Tegelberg
Mikael
M
Brosché
Markku
M
Keinänen
Anders
A
Lindfors
Pedro J
PJ
Aphalo
D029662:Betula / Q000378:metabolism* / Q000528:radiation effects*; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects*; D010636:Phenols / Q000378:metabolism*; D018515:Plant Leaves / Q000378:metabolism / Q000528:radiation effects; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D036226:Seedlings / Q000378:metabolism / Q000528:radiation effects; D013472:Sunlight; D014466:Ultraviolet Rays
D010636:Phenols; D010940:Plant Proteins