Neugart Susanne, Majer Petra, Schreiner Monika, Hideg Éva
Division Quality and Sensory of Plant Products, Georg-August-Universität Göttingen, Göttingen, Germany.
Institute of Plant Biology, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary.
Front Plant Sci. 2021 Jan 28;11:611247. doi: 10.3389/fpls.2020.611247. eCollection 2020.
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 day UV-B), which was followed with two subsequent (equals 2 days) doses of either blue (99 μmol m s) or green (119 μmol m s) light. In sprouts of kale, kohlrabi, and rocket salad, flavonoid glycosides were identified by HPLC-DAD-ESI-MS. Both 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 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.
紫外线B（UV-B；280 - 315纳米）辐射可诱导植物次生代谢产物如类黄酮的生物合成。蓝光（420 - 490纳米）或绿光（490 - 585纳米）也可增强类黄酮的含量。类黄酮在植物对UV-B照射的反应中起到抗氧化剂和屏蔽成分的作用。它们能淬灭单线态氧并对羟基自由基具有反应活性。本研究的目的是确定在预先暴露于UV-B后，蓝光或绿光处理是否能改变十字花科芽苗菜中的类黄酮谱，以及它们是否会在十字花科芽苗菜中产生相应的生物学效应。基于它们不同的类黄酮谱，从十字花科中选择了三种蔬菜。芽苗菜先接受五剂（相当于5天）中等强度的UV-B（0.23千焦·平方米·天的UV-B）处理，随后再接受两剂（相当于2天）蓝光（99微摩尔·平方米·秒）或绿光（119微摩尔·平方米·秒）处理。通过高效液相色谱 - 二极管阵列 - 电喷雾电离质谱联用（HPLC-DAD-ESI-MS）对羽衣甘蓝、球茎甘蓝和芝麻菜芽苗菜中的类黄酮糖苷进行了鉴定。羽衣甘蓝和球茎甘蓝这两个品种主要显示出酰化槲皮素和山奈酚糖苷。相比之下，芝麻菜中的主要黄酮醇糖苷是槲皮素糖苷。UV-B处理后的蓝光处理表明，羽衣甘蓝和球茎甘蓝品种中的槲皮素和山奈酚糖苷含量增加，而与此相反，在芝麻菜中，只有槲皮素糖苷含量增加。总体而言，蓝光处理稳定了类黄酮糖苷增加的浓度，而绿光处理则没有这种效果。UV-B照射后的蓝光处理导致羽衣甘蓝和芝麻菜的单线态氧清除能力呈增加趋势。除了羽衣甘蓝，羟基自由基清除能力与光质无关，在羽衣甘蓝中，UV-B照射后再进行蓝光处理会导致更高的羟基自由基清除能力。这些结果强调了不同光质对拦截植物次生代谢产物的活性氧生物合成的重要性，但也显示出明显的物种依赖性反应，这对种植者具有特殊意义。
