Guangdong Laboratory for Lingnan Modern Agriculture, College of Life Sciences, South China Agricultural University, Guangzhou 510642, China; State Key Laboratory of Agricultural Genomics, BGI-Shenzhen, Shenzhen 518083, China.
State Key Laboratory of Agricultural Genomics, BGI-Shenzhen, Shenzhen 518083, China.
Plant Sci. 2022 Dec;325:111489. doi: 10.1016/j.plantsci.2022.111489. Epub 2022 Oct 8.
Citrus grandis 'Tomentosa' (CGT) (Huajuhong, HJH) is a widely used medicinal plant, which is mainly produced in Guangdong and Guangxi provinces of South China. Particularly, HJH from Huazhou (HZ) county of Guangdong province has been well-regarded as the best national product for geo-herbalism. But the reasons for geo-herbalism property in HJH from HZ county remains a mystery. Therefore, a multi-omics approach was applied to identify the nature of the geo-herbalism in CGT from three different regions. The comprehensive screening of differential metabolites revealed that the Nobiletin content was significantly different in HZ region compared to other regions, and could be employed as a key indicator to determine the geo-herbalism. Furthermore, the high-quality genome (N50 of 9.12 Mb), coupled with genomics and transcriptomics analyses indicated that CGT and Citrus grandis are closely related, with a predicted divergence time of 19.1 million years ago (MYA), and no recent WGD occurred in the CGT, and the bioactive ingredients of CGT were more abundant than that of Citrus grandis. Interestingly, Nobiletin (Polymethoxyflavones) content was identified as a potential indicator of geo-herbalism, and O-methyltransferase (OMT) genes are involved in the synthesis of Polymethoxyflavones. Further multi-omics analysis led to the identification of a novel OMT gene (CtgOMT1) whose transient overexpression displayed significantly higher Nobiletin content, suggesting that CtgOMT1 was involved in the synthesis of Nobiletin. Overall, our findings provide new data resources for geo-herbalism evaluation, germplasm conservation and insights into Nobiletin biosynthesis pathways for the medicinal plant C. grandis 'Tomentosa'.
“Huajuhong”（化橘红，HJH）是一种广泛应用的药用植物，主要产于中国华南的广东和广西两省。特别是广东化州（HZ）县的 HJH 被公认为全国地理标志产品。然而，HZ 县 HJH 产生地理标志属性的原因仍不清楚。因此，采用多组学方法来鉴定来自三个不同地区的 CG 的地理标志属性。综合筛选差异代谢物表明，与其他地区相比，HZ 地区的诺必灵含量有显著差异，可作为判断地理标志的关键指标。此外，高质量的基因组（N50 为 9.12Mb），结合基因组学和转录组学分析表明，CGT 和柑橘属亲缘关系密切，预测分化时间为 1910 万年前（MYA），CGT 中没有发生近期的全基因组复制（WGD），CGT 的生物活性成分比柑橘属更丰富。有趣的是，诺必灵（多甲氧基黄酮）含量被确定为地理标志的潜在指标，而 O-甲基转移酶（OMT）基因参与多甲氧基黄酮的合成。进一步的多组学分析确定了一个新的 OMT 基因（CtgOMT1），其瞬时过表达显示出显著更高的诺必灵含量，表明 CtgOMT1 参与了诺必灵的合成。总的来说，我们的研究结果为地理标志评价、种质资源保护以及药用植物 CG 的诺必灵生物合成途径提供了新的数据资源。
