Michelia maudiae Dunn is one of the important ornamental plants in the Magnoliaceae family, and the color of its flowers usually appears naturally pure white. The discovery of a rubellis flower named M. maudiae Dunn var. rubicunda provides an opportunity to reveal the metabolism of the flavonoids and anthocyanins of this “early angiosperm” plant. Combined metabolome and transcriptome analyses were applied using white and rubellis mutant tepals. Seven stages have been divided for flower development, and forty-eight differentially altered metabolites were identified between white and rubellis tepals at a later stage. The major anthocyanins including peonidin O-hexoside, cyanidin O-syringic acid, cyanidin 3,5-O-diglucoside, cyanidin 3-O-glucoside, and pelargonidin 3-O-glucoside were upregulated over 157-fold in the mutant. Conversely, the highly significant accumulation of the colorless procyanidin or the slightly yellow epicatechin and catechin was found in white flowers. Putative homologues of color-related genes involved in the phenylpropanoid and flavonoid biosynthesis pathway were identified in the transcriptome. The increasing expression of dihydroflavonol 4-reductase (DFR) might play an important role in the occurrence of rubellis pigments, while the overexpression of anthocyanidin reductase (ANR) in white flowers may promote the biosynthesis of proanthocyanidins. Additionally, several coloration-related repressor R2R3-MYB transcription factors showed different expression levels in the tepals of the rubellis mutant. This study provides a comprehensive analysis relating color compounds to gene expression profiles of the Magnoliids plant M. maudiae. The newly generated information will provide a profound effect on horticultural applications of Magnoliaceae.

中文翻译：

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整合的代谢组和转录组分析揭示了花色苷代谢在含笑中的作用。

含笑含笑邓恩是木兰科重要的观赏植物之一，其花朵的颜色通常看起来自然是纯白色。发现了一种名为M. maudiae Dunn var的风铃草花。rubicunda提供了一个机会来揭示这种“早期被子植物”植物的类黄酮和花色苷的代谢。结合代谢组和转录组分析使用白色和风果突变体tepals。花的发育分为七个阶段，在后期阶段，在白色和风铃石之间鉴定出48种差异变化的代谢产物。主要花色苷包括：peonidin O-己糖苷，cyanidin O-丁香酸，cyanidin 3,5- O-diglucoside，矢车菊3- Ó葡糖苷，花葵素和3- Ó葡糖苷在突变体中上调超过157倍。相反，在白花中发现了无色原花青素或浅黄色表儿茶素和儿茶素的高度显着积累。在转录组中鉴定出与苯丙烷和类黄酮生物合成途径有关的颜色相关基因的推定同源物。二氢黄酮醇4-还原酶（DFR）的表达增加可能在风疹色素的发生中起重要作用，而花青素还原酶（ANR）的过表达）在白色花朵中可能会促进原花青素的生物合成。此外，一些与着色相关的阻遏物R2R3-MYB转录因子在风疹突变体的花鼓中表现出不同的表达水平。这项研究提供了一种全面的分析方法，将颜色化合物与木兰科植物M. maudiae的基因表达谱联系起来。新生成的信息将对木兰科的园艺应用产生深远影响。