Geranyllinalool Synthases in Solanaceae and Other Angiosperms Constitute an Ancient Branch of Diterpene Synthases Involved in the Synthesis of Defensive Compounds
Geranyllinalool Synthases in Solanaceae and Other Angiosperms Constitute an Ancient Branch of Diterpene Synthases Involved in the Synthesis of Defensive Compounds
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DOI：
10.1104/pp.114.243246
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发表时间：
2014-09-01
期刊：
影响因子：
7.4
通讯作者：
Pichersky, Eran
中科院分区：
文献类型：
--
作者：
Falara, Vasiliki;Alba, Juan M.;Pichersky, Eran
许多被子植物，包括双子叶植物、真双子叶植物和单子叶植物，在生物胁迫下会释放出（E，E）-4，8，12-三甲基十三碳-1，3，7，11-四烯，其来源于香叶基芳樟醇。已报道了一种属于萜合酶（TPS）家族e/f进化枝的拟南芥（Arabidopsis thaliana）香叶基芳樟醇合酶（GLS）和两种属于TPS-g进化枝的豆科GLS，但尚不清楚哪种是植物中香叶基芳樟醇的主要途径。本研究鉴定了一个番茄（Solanum lycopersicum）TPS-e/f基因TPS 46，该基因编码来自烟草（Nicotiana attenuata）的GLS（SlGLS）及其同源物（NaGLS）。SlGLS对香叶基香叶基二磷酸的Km值为18.7 μ M，周转率值为6.85 s（-1）。在N.组成型合成17-羟基香叶基芳樟醇糖苷的基因，NaGLS组成型表达，但该基因可以在茉莉酸甲酯的诱导下在叶片中表达。在番茄中，SlGLS在正常生长的任何组织中不表达，但在叶片中被丙甲霉素和茉莉酸甲酯处理诱导。SlGLS、NaGLS、AtGLS和几种仅在体外表征的其他GLS来自四个不同的真双子叶植物科，并且构成了在裸子植物-被子植物分裂之前从贝壳杉烯脱氢酶（也在TPS-e/f进化枝中）分支的TPS-e/f进化枝的单独分支。这一分支的早期分化和不同真双子叶植物家族中这一分支中基因的GLS活性表明，这些基因编码的GLS活性早于被子植物-裸子植物的分裂。然而，尽管最近报道了一个属于GLS谱系的TPS序列，但在单子叶植物或非被子植物中尚未发现有代表性的序列。
Many angiosperm plants, including basal dicots, eudicots, and monocots, emit (E, E)-4,8,12-trimethyltrideca-1,3,7,11-tetraene, which is derived from geranyllinalool, in response to biotic challenge. An Arabidopsis (Arabidopsis thaliana) geranyllinalool synthase (GLS) belonging to the e/f clade of the terpene synthase (TPS) family and two Fabaceae GLSs that belong to the TPS-g clade have been reported, making it unclear which is the main route to geranyllinalool in plants. We characterized a tomato (Solanum lycopersicum) TPS-e/f gene, TPS46, encoding GLS (SlGLS) and its homolog (NaGLS) from Nicotiana attenuata. The K-m value of SlGLS for geranylgeranyl diphosphate was 18.7 mu M, with a turnover rate value of 6.85 s(-1). In leaves and flowers of N. attenuata, which constitutively synthesize 17-hydroxygeranyllinalool glycosides, NaGLS is expressed constitutively, but the gene can be induced in leaves with methyl jasmonate. In tomato, SlGLS is not expressed in any tissue under normal growth but is induced in leaves by alamethicin and methyl jasmonate treatments. SlGLS, NaGLS, AtGLSs, and several other GLSs characterized only in vitro come from four different eudicot families and constitute a separate branch of the TPS-e/f clade that diverged from kaurene synthases, also in the TPS-e/f clade, before the gymnosperm-angiosperm split. The early divergence of this branch and the GLS activity of genes in this branch in diverse eudicot families suggest that GLS activity encoded by these genes predates the angiosperm-gymnosperm split. However, although a TPS sequence belonging to this GLS lineage was recently reported from a basal dicot, no representative sequences have yet been found in monocot or nonangiospermous plants.