Phenylpropanoids are a large class of plant secondary metabolites derived from aromatic amino acids phenylalanine in most plants or tyrosine in partial monocots. It mainly includes flavonoids, monolignols, phenolic acids, stilbenes, and coumarins. Phenylpropanoids are widely distributed in the plant kingdom and play vital roles in plant development by acting as essential components of cell walls, protectants against high light and UV radiation, phytoalexins against herbivores and pathogens, floral pigments to mediate plant–pollinator interactions. In addition, phenylpropanoids possess diverse biological activities that are beneficial to human health. In the past decades, the structure and function of phenylpropanoids and the biosynthetic pathways of flavonoids, monolignols and phenolic acids have been extensively studied. Recent results showed that miR828, ta-siRNAs and R2R3-MYBs play critical regulatory roles in phenylpropanoid biosynthesis through two modes: either the miR828–MYB–phenylpropanoid biosynthesis cascade in which MYB transcripts are directly cleaved by miR828, or the miR828–ta-siRNA–MYB–phenylpropanoid biosynthesis cascade under the mediation of TAS4- or MYB-derived ta-siRNAs. In this review, we overview the structure, function and biosynthetic pathway of phenylpropanoids and summarize the complex regulatory mechanism of phenylpropanoid biosynthesis with a focus on the two cascades involving miR828, ta-siRNAs and MYBs.

中文翻译：

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植物苯丙烷的生物合成与调控

苯丙烷类化合物是一类植物的次生代谢产物，其衍生自大多数植物中的芳香族氨基酸苯丙氨酸或部分单子叶植物中的酪氨酸。它主要包括类黄酮，单木酚，酚酸，丁苯醚和香豆素。苯丙烷类化合物在植物界广泛分布，并通过充当细胞壁的必需成分，抗强光和紫外线辐射的保护剂，抗草食动物和病原体的植物抗毒素，花色素来介导植物与授粉媒介的相互作用，在植物发育中发挥至关重要的作用。另外，苯丙烷具有多种有益于人体健康的生物活性。在过去的几十年中，对苯丙烷的结构和功能以及类黄酮，单木酚和酚酸的生物合成途径进行了广泛的研究。MYB –苯丙烷生物合成级联，其中miB828直接切割MYB转录物，或在TAS4或MYB衍生的ta-siRNA的介导下，miR828–ta-siRNA – MYB –苯丙烷生物合成级联。在这次审查中，我们概述了结构，功能和苯丙素生物合成途径和总结苯丙生物合成的复杂的监管机制，重点对涉及miR828两个瀑布，TA-siRNA和MYBS。