Neugart Susanne, Tobler Mark A, Barnes Paul W
Division Quality and Sensory of Plant Products, Georg-August-Universität Göttingen, 37075 Goettingen, Germany.
Department of Biological Sciences, Loyola University New Orleans, 6363 St. Charles Avenue, New Orleans, LA 70118, USA.
Plants (Basel). 2021 Oct 22;10(11):2268. doi: 10.3390/plants10112268.
Flavonoids are favored compounds in plant responses to UV exposure and act in UV absorption and antioxidant activity. Here, it was investigated, with okra as a model species, how fast plants can react to changing UV conditions and to what extent these reactions take place. Okra () plants were exposed to either full or nearly no UV radiation. The diurnal rhythm of the plants was driven by the UV radiation and showed up to a 50% increase of the flavonoid content (measured optically in the +UV plants). This was reflected only in the trends in UV-absorption and antioxidant activity of the extracts but not in the soluble flavonoid glycosides and hydroxycinnamic acid derivatives. In a second experiment, a transfer from a -UV to a +UV condition at 9:00 CDT showed the immediate start of the diurnal rhythm, while this did not occur if the transfer occurred later in the day; these plants only started a diurnal rhythm the following day. After an adaptation period of seven days, clear differences between the +UV and -UV plants could be found in all parameters, whereas plants transferred to the opposite UV condition settle between the +UV and -UV plants in all parameters. Broadly, it can be seen that the flavonoid contents and associated functions in the plant are subject to considerable changes within one day and within several days due to the UV conditions and that this can have a considerable impact on the quality of plant foods.
类黄酮是植物对紫外线照射作出反应时所青睐的化合物，具有紫外线吸收和抗氧化活性。在此，以秋葵作为模式物种，研究了植物对变化的紫外线条件的反应速度以及这些反应的发生程度。秋葵（）植株分别暴露于全紫外线辐射或几乎无紫外线辐射的环境中。植株的昼夜节律受紫外线辐射驱动，在暴露于紫外线的植株中，类黄酮含量（通过光学方法测量）最多增加了50%。这仅反映在提取物的紫外线吸收和抗氧化活性趋势上，而在可溶性类黄酮糖苷和羟基肉桂酸衍生物中未体现。在第二个实验中，美国中部夏令时间9:00从无紫外线条件转移到有紫外线条件下，昼夜节律立即开始，而如果在当天晚些时候进行转移则不会出现这种情况；这些植株仅在第二天开始出现昼夜节律。经过七天的适应期后，在所有参数方面，暴露于紫外线和未暴露于紫外线的植株之间出现了明显差异，而转移到相反紫外线条件下的植株在所有参数方面都介于暴露于紫外线和未暴露于紫外线的植株之间。总体而言，可以看出，由于紫外线条件，植物中的类黄酮含量及其相关功能在一天内和数天内会发生相当大的变化，这可能会对植物性食物的质量产生相当大的影响。
