Data_Sheet_2_Blue Light Treatment but Not Green Light Treatment After Pre-exposure to UV-B Stabilizes Flavonoid Glycoside Changes and Corresponding Biological Effects in Three Different Brassicaceae Sprouts.PDF

Ultraviolet-B (UV-B; 280–315 nm) radiation induces the biosynthesis of secondary plant metabolites such as flavonoids. Flavonoids could also be enhanced by blue (420–490 nm) or green (490–585 nm) light. Flavonoids act as antioxidants and shielding components in the plant’s response to UV-B exposure. They are shown to quench singlet oxygen and to be reactive to hydroxyl radical. The aim was to determine whether treatment with blue or green light can alter flavonoid profiles after pre-exposure to UV-B and whether they cause corresponding biological effects in Brassicaceae sprouts. Based on their different flavonoid profiles, three vegetables from the Brassicaceae were selected. Sprouts were treated with five subsequent doses (equals 5 days) of moderate UV-B (0.23 kJ m–2 day–1 UV-BBE), which was followed with two subsequent (equals 2 days) doses of either blue (99 μmol m–2 s–1) or green (119 μmol m–2 s–1) light. In sprouts of kale, kohlrabi, and rocket salad, flavonoid glycosides were identified by HPLC-DAD-ESI-MSn. Both Brassica oleracea species, kale and kohlrabi, showed mainly acylated quercetin and kaempferol glycosides. In contrast, in rocket salad, the main flavonol glycosides were quercetin glycosides. Blue light treatment after the UV-B treatment showed that quercetin and kaempferol glycosides were increased in the B. oleracea species kale and kohlrabi while—contrary to this—in rocket salad, there were only quercetin glycosides increased. Blue light treatment in general stabilized the enhanced concentrations of flavonoid glycosides while green treatment did not have this effect. Blue light treatment following the UV-B exposure resulted in a trend of increased singlet oxygen scavenging for kale and rocket. The hydroxyl radical scavenging capacity was independent from the light quality except for kale where an exposure with UV-B followed by a blue light treatment led to a higher hydroxyl radical scavenging capacity. These results underline the importance of different light qualities for the biosynthesis of reactive oxygen species that intercept secondary plant metabolites, but also show a pronounced species-dependent reaction, which is of special interest for growers.

紫外-B（UV-B；280–315 nm）辐射可诱导次生植物代谢产物如黄酮类物质的生物合成。黄酮类物质还可通过蓝光（420–490 nm）或绿光（490–585 nm）得到增强。黄酮类物质在植物对UV-B辐射的响应中充当抗氧化剂和屏蔽成分。研究表明，它们能够淬灭单线态氧并对其羟基自由基产生反应。研究旨在确定，在预先暴露于UV-B之后，蓝光或绿光处理是否能改变黄酮类物质的谱系，以及它们是否会在羽衣甘蓝芽苗中引起相应的生物学效应。基于其不同的黄酮类物质谱系，选定了三种十字花科蔬菜。芽苗接受了五次连续的中度UV-B处理（等于5天），随后是两次连续的（等于2天）蓝光（99 μmol m–2 s–1）或绿光（119 μmol m–2 s–1）处理。在羽衣甘蓝、芜菁和火箭生菜的芽苗中，通过HPLC-DAD-ESI-MSn技术鉴定了黄酮糖苷。两种羽衣甘蓝属物种，羽衣甘蓝和芜菁，主要含有酰化槲皮素和山奈酚糖苷。相比之下，在火箭生菜中，主要的黄酮醇糖苷是槲皮素糖苷。UV-B处理后的蓝光处理显示，在羽衣甘蓝和芜菁的B. oleracea物种中，槲皮素和山奈酚糖苷含量增加，而与这一现象相反，在火箭生菜中仅槲皮素糖苷含量增加。总体而言，蓝光处理稳定了黄酮糖苷的增强浓度，而绿光处理则没有这种效果。UV-B暴露后的蓝光处理导致羽衣甘蓝和火箭生菜的单线态氧清除能力呈增加趋势。羟基自由基清除能力与光质无关，但在羽衣甘蓝中，UV-B暴露后进行蓝光处理导致羟基自由基清除能力更高。这些结果突出了不同光质对截获次生植物代谢产物的活性氧生物合成的重要性，同时也显示了一种显著的物种特异性反应，这对种植者来说具有重要意义。