Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
State Key Laboratory for Quality Ensurance and Sustainable Use of Dao-di Herbs, Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, China.
Physiol Plant. 2024 Sep-Oct;176(5):e14508. doi: 10.1111/ppl.14508.
Camptotheca acuminata Decne., a significant natural source of the anticancer drug camptothecin (CPT), synthesizes CPT through the monoterpene indole alkaloid (MIA) pathway. In this study, we used single-cell RNA sequencing (scRNA-seq) to generate datasets encompassing over 60,000 cells from C. acuminata shoot apexes and leaves. After cell clustering and annotation, we identified five major cell types in shoot apexes and four in leaves. Analysis of MIA pathway gene expression revealed that most of them exhibited heightened expression in proliferating cells (PCs) and vascular cells (VCs). In contrast to MIA biosynthesis in Catharanthus roseus, CPT biosynthesis in C. acuminata did not exhibit multicellular compartmentalization. Some putative genes encoding enzymes and transcription factors (TFs) related to the biosynthesis of CPT and its derivatives were identified through co-expression analysis. These include 19 cytochrome P450 genes, 8 O-methyltransferase (OMT) genes, and 62 TFs. Additionally, these pathway genes exhibited dynamic expression patterns during VC and EC development. Furthermore, by integrating gene and transposable element (TE) expression data, we constructed novel single-cell transcriptome atlases for C. acuminata. This approach significantly facilitated the identification of rare cell types, including peripheral zone cells (PZs). Some TE families displayed cell type specific, tissue specific, or developmental stage-specific expression patterns, suggesting crucial roles for these TEs in cell differentiation and development. Overall, this study not only provides novel insights into CPT biosynthesis and spatial-temporal TE expression characteristics in C. acuminata, but also serves as a valuable resource for further comprehensive investigations into the development and physiology of this species.
喜树，一种重要的天然抗癌药物喜树碱（CPT）的来源，通过单萜吲哚生物碱（MIA）途径合成 CPT。在这项研究中，我们使用单细胞 RNA 测序（scRNA-seq）技术从喜树的茎尖和叶片中生成了超过 60,000 个细胞的数据集。在细胞聚类和注释后，我们在茎尖和叶片中分别鉴定出了 5 种主要细胞类型和 4 种细胞类型。对 MIA 途径基因表达的分析表明，它们中的大多数在增殖细胞（PCs）和血管细胞（VCs）中表达水平较高。与长春花中的 MIA 生物合成不同，喜树中的 CPT 生物合成没有表现出多细胞区室化。通过共表达分析，我们鉴定出了一些与 CPT 及其衍生物生物合成相关的酶和转录因子（TF）的假定基因，包括 19 个细胞色素 P450 基因、8 个 O-甲基转移酶（OMT）基因和 62 个 TF。此外，这些途径基因在 VC 和 EC 发育过程中表现出动态表达模式。此外，通过整合基因和转座元件（TE）表达数据，我们构建了喜树新的单细胞转录组图谱。这种方法极大地促进了稀有细胞类型的鉴定，包括周缘区细胞（PZs）。一些 TE 家族表现出细胞类型特异性、组织特异性或发育阶段特异性表达模式，表明这些 TE 在细胞分化和发育中起着关键作用。总的来说，这项研究不仅为喜树中 CPT 生物合成和时空 TE 表达特征提供了新的见解，而且为进一步全面研究该物种的发育和生理学提供了有价值的资源。
