Department of Biosciences, Division of Plant Biology, PO Box 65 (Biocenter 3, Viikinkaari 1), FIN-00014, University of Helsinki, Helsinki, Finland.
Tree Physiol. 2010 Jul;30(7):923-34. doi: 10.1093/treephys/tpq051. Epub 2010 Jun 2.
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.
紫外线（UV）辐射是植物群落的一个重要环境因素；然而，植物对太阳 UV 的反应还不完全清楚。在这里，我们报告了太阳 UV-A 和 UV-B 辐射对户外生长的银桦（Betula pendula Roth）幼苗叶片中类黄酮途径基因表达和酚类物质积累的差异影响。植物在三种类型的塑料薄膜下接受了 30 天的 6 种 UV 处理。当排除 UV-B 时，体内测量的表皮类黄酮减少。此外，通过高效液相色谱-质谱法测定的六种类黄酮的浓度与 UV-B 排除呈线性下降，通过定量实时聚合酶链反应测量的 PAL 和 HYH 转录本的表达水平较低。UV-A 线性调节槲皮素-3-半乳糖苷和槲皮素-3-阿拉伯吡喃糖苷的积累，并对 HYH 表达有二次效应。此外，在 UV 处理下，PAL 表达与四种类黄酮醇的积累之间存在强烈的正相关关系。我们在银桦中的发现有助于更详细地了解植物对太阳 UV 辐射的分子和代谢物水平的反应。
