Department of Plant Biology, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran.
Department of Plant Biology, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran; Center of Excellence in Medicinal Plant Metabolites, Tarbiat Modares University, Tehran, Iran.
J Photochem Photobiol B. 2021 Dec;225:112326. doi: 10.1016/j.jphotobiol.2021.112326. Epub 2021 Oct 1.
Phenylethanoid glycosides (PhGs) are important medicinal compounds found in Scrophularia striata, one of the plant species native to Iran. Since almost all aspects of plant life are controlled by night/light cycle, studying its relationship to valuable plant metabolites production will help us to determine the right time for their extraction. Therefore, the aim of this investigation is to figure out whether the diel light oscillations control PhGs production and how it relates to daily changes in upstream metabolic reactions and circadian clock in S. striata. For this, daily rhythms of metabolic pathways were examined every 4 h during a day/night cycle in 3 groups of control (16 h light/8 h dark), continuous light and darkness. The results showed that acteoside and echinacoside levels in each group peaked during the night and day, respectively. Thus, the PhGs production follows a rhythmic behavior in S. striata, which is probably controlled by circadian clock. Also, the levels of photosynthetic pigments, carbohydrates, amino acids, phenolic acids, phytohormones and phenylalanine ammonia-lyase (PAL) and tyrosine ammonia-lyase (TAL) enzyme activities varied diel in a similar or different way among study groups. The observations revealed that light/dark cycle controls the carbon and energy flow from light reception to the production and consumption of starch, biosynthesis of phenylalanine, tyrosine, cinnamic acid and coumaric acid, activation of hormonal signaling pathways and enzymes involved in phenylpropanoid pathway. Overall, it can be concluded that PhGs accumulation time-dependent patterns is likely due to daily fluctuations in upstream metabolic reactions induced by light/dark cycle.
苯乙醇苷类化合物（PhGs）是贯叶连翘中的重要药用化合物，贯叶连翘是原产于伊朗的植物物种之一。由于植物生命的几乎所有方面都受昼夜/光照周期的控制，研究其与有价值的植物代谢产物生产的关系将有助于我们确定提取它们的正确时间。因此，本研究的目的是确定昼夜光振荡是否控制 PhGs 的产生，以及它如何与贯叶连翘中上游代谢反应和生物钟的日常变化相关。为此，在白天/黑夜周期的 3 组对照（16 小时光照/8 小时黑暗）、连续光照和黑暗中，每 4 小时检查一次代谢途径的日常节律。结果表明，每组中的咖啡酰牡荆苷和毛蕊花糖苷水平分别在夜间和白天达到峰值。因此，PhGs 的产生在贯叶连翘中呈现出节律性行为，这可能受生物钟控制。此外，光合色素、碳水化合物、氨基酸、酚酸、植物激素和苯丙氨酸氨裂解酶（PAL）和酪氨酸氨裂解酶（TAL）酶活性的水平在研究组中以相似或不同的方式呈昼夜变化。这些观察结果表明，光/暗周期控制着从光接收到淀粉的生产和消耗、苯丙氨酸、酪氨酸、肉桂酸和香豆酸的生物合成、激素信号通路的激活以及苯丙烷途径中涉及的酶的碳和能量流动。总的来说，可以得出结论，PhGs 积累的时间依赖性模式可能是由于光/暗周期引起的上游代谢反应的日常波动。
