Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences , Nanjing Normal University , Nanjing , Jiangsu 210023 , People's Republic of China.
J Agric Food Chem. 2018 May 30;66(21):5392-5400. doi: 10.1021/acs.jafc.8b01795. Epub 2018 May 21.
As a plant-specific flavonoid type metabolite, anthocyanin is an important plant-sourced nutrition. Although the anthocyanin biosynthesis pathway has been revealed, how to modulate anthocyanin production by endogenous molecules is still elusive. Here, we investigated the role of melatonin in anthocyanin biosynthesis in the reference plant Arabidopsis thaliana and found that melatonin suppresses anthocyanin synthesis. Moreover, melatonin was able to significantly inhibit jasmonate-stimulated anthocyanin production. Unexpectedly, melatonin could not repress the jasmonate-triggered JAZ protein degradation that is a key event for relaying jasmonate signaling. The expression of jasmonate-induced marker genes or other jasmonate-related phenotypes were not discernibly changed in the presence of melatonin. These results indicate that the antagonization of jasmonate-induced anthocyanin synthesis by melatonin does not occur through the abrogation of jasmonate signaling. Furthermore, we found that melatonin does not trigger anthocyanin catabolism. Finally, we supplied anthocyanin biosynthesis precursors to examine their roles in anthocyanin biosynthesis and found that melatonin most likely acts before the dihydrokaempferol production step. Our work illustrates that melatonin plays a negative role in the induction of anthocyanin biosynthesis and sheds new light on the role of melatonin in plant cell metabolism.
作为一种植物特异性类黄酮代谢物，花色苷是一种重要的植物源营养素。尽管花色苷生物合成途径已经被揭示，但如何通过内源性分子来调节花色苷的产生仍然难以捉摸。在这里，我们研究了褪黑素在模式植物拟南芥中花色苷生物合成中的作用，发现褪黑素抑制花色苷的合成。此外，褪黑素能够显著抑制茉莉酸刺激的花色苷产生。出乎意料的是，褪黑素不能抑制茉莉酸触发的 JAZ 蛋白降解，而 JAZ 蛋白降解是茉莉酸信号转导的关键事件。在褪黑素存在的情况下，茉莉酸诱导的标记基因或其他与茉莉酸相关的表型没有明显改变。这些结果表明，褪黑素对茉莉酸诱导的花色苷合成的拮抗作用不是通过消除茉莉酸信号转导来实现的。此外，我们发现褪黑素不会触发花色苷的分解代谢。最后，我们提供花色苷生物合成前体来研究它们在花色苷生物合成中的作用，发现褪黑素很可能在二氢山奈酚的产生步骤之前发挥作用。我们的工作说明了褪黑素在花色苷生物合成的诱导中起着负作用，并为褪黑素在植物细胞代谢中的作用提供了新的视角。
