The leaf epidermome of Catharanthus roseus reveals its biochemical specialization
The leaf epidermome of Catharanthus roseus reveals its biochemical specialization
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DOI：
10.1105/tpc.107.056630
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发表时间：
2008-03-01
期刊：
影响因子：
11.6
通讯作者：
De Luca, Vincenzo
中科院分区：
文献类型：
--
作者：
Murata, Jun;Roepke, Jonathon;De Luca, Vincenzo
长春花是单萜吲哚生物碱 (MIA)、长春花碱和长春花碱的唯一商业来源，它们是商业上重要的抗癌二聚体、长春花碱和长春新碱的成分。使用碳化硅磨损技术提取叶表皮富集的 mRNA，从而对叶表皮中表达的蛋白质的表皮或补体进行取样。对衍生的 cDNA 文库进行随机测序，建立了 3655 个独特的 EST，由 1142 个簇和 2513 个单例组成。事实上，所有已知的 MIA 途径基因都在这组引人注目的 EST 中被发现，而在公开的长春花 EST 数据集中只发现了 4 个已知基因。几个新的 MIA 途径候选基因被鉴定出来，如参与 secologanin 生物合成的马钱酸 O-甲基转移酶的克隆和功能表征所证明的。还确定了三萜生物合成的途径，代谢物分析表明齐墩果烷型三萜仅位于角质层蜡层。类黄酮和极长链脂肪酸生物合成的途径也位于这种细胞类型中。结果阐明了长春花叶表皮产生多类代谢物的生化专门性。还讨论了该 EST 数据集对于叶表皮细胞生化和生物分析的价值和多功能性。
Catharanthus roseus is the sole commercial source of the monoterpenoid indole alkaloids (MIAs), vindoline and catharanthine, components of the commercially important anticancer dimers, vinblastine and vincristine. Carborundum abrasion technique was used to extract leaf epidermis-enriched mRNA, thus sampling the epidermome, or complement, of proteins expressed in the leaf epidermis. Random sequencing of the derived cDNA library established 3655 unique ESTs, composed of 1142 clusters and 2513 singletons. Virtually all known MIA pathway genes were found in this remarkable set of ESTs, while only four known genes were found in the publicly available Catharanthus EST data set. Several novel MIA pathway candidate genes were identified, as demonstrated by the cloning and functional characterization of loganic acid O-methyltransferase involved in secologanin biosynthesis. The pathways for triterpene biosynthesis were also identified, and metabolite analysis showed that oleanane-type triterpenes were localized exclusively to the cuticular wax layer. The pathways for flavonoid and very-long-chain fatty acid biosynthesis were also located in this cell type. The results illuminate the biochemical specialization of Catharanthus leaf epidermis for the production of multiple classes of metabolites. The value and versatility of this EST data set for biochemical and biological analysis of leaf epidermal cells is also discussed.