Pummelo (Citrus maxima or Citrus grandis) is a basic species and an important type for breeding in Citrus. Pummelo is used not only for fresh consumption but also for medicinal purposes. However, the molecular basis of medicinal traits is unclear. Here, compared with wild citrus species/Citrus-related genera, the content of 43 bioactive metabolites and their derivatives increased in the pummelo. Furthermore, we assembled the genome sequence of a variety for medicinal purposes with a long history, Citrus maxima ‘Huazhouyou-tomentosa’ (HZY-T), at the chromosome level with a genome size of 349.07 Mb. Comparative genomics showed that the expanded gene family in the pummelo genome was enriched in flavonoids-, terpenoid-, and phenylpropanoid biosynthesis. Using the metabolome and transcriptome of six developmental stages of HZY-T and Citrus maxima ‘Huazhouyou-smooth’ (HZY-S) fruit peel, we generated the regulatory networks of bioactive metabolites and their derivatives. We identified a novel MYB transcription factor, CmtMYB108, as an important regulator of flavone pathways. Both mutations and expression of CmtMYB108, which targets the genes PAL (phenylalanine ammonia-lyase) and FNS (flavone synthase), displayed differential expression between Citrus-related genera, wild citrus species and pummelo species. This study provides insights into the evolution-associated changes in bioactive metabolism during the origin process of pummelo.

中文翻译：

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进化引导的多组学为加强药用柚子中生物活性黄酮的生物合成提供了见解

柚子（Citrus maxima或Citrus grandis）是柑橘的基本品种和重要育种类型。柚子不仅可鲜食，还可入药。然而，药用性状的分子基础尚不清楚。与野生柑橘属/柑橘相关属相比，柚子中 43 种生物活性代谢物及其衍生物的含量有所增加。此外，我们还在染色体水平上组装了历史悠久的药用品种“化州优毛白柑”（HZY-T）的基因组序列，基因组大小为349.07 Mb。比较基因组学表明，柚子基因组中扩展的基因家族富含黄酮类、萜类和苯丙素生物合成。利用 HZY-T 和柑橘“化州优光滑”（HZY-S）果皮六个发育阶段的代谢组和转录组，我们生成了生物活性代谢物及其衍生物的调控网络。我们发现了一种新型 MYB 转录因子 CmtMYB108，它是黄酮途径的重要调节因子。CmtMYB108的突变和表达均以PAL（苯丙氨酸解氨酶）和FNS（黄酮合酶）基因为目标，在柑橘相关属、野生柑橘属和柚子属之间表现出差异表达。这项研究提供了对柚子起源过程中生物活性代谢与进化相关的变化的见解。