Department of Plant Sciences, University of Tennessee, Knoxville, TN 37996, USA.
Proc Natl Acad Sci U S A. 2012 Sep 4;109(36):14711-5. doi: 10.1073/pnas.1204300109. Epub 2012 Aug 20.
Terpene synthases (TPSs) are pivotal enzymes for the biosynthesis of terpenoids, the largest class of secondary metabolites made by plants and other organisms. To understand the basis of the vast diversification of these enzymes in plants, we investigated Selaginella moellendorffi, [corrected] a nonseed vascular plant. The genome of this species was found to contain two distinct types of TPS genes. The first type of genes, which was designated as S. moellendorffi [corrected] TPS genes (SmTPSs), consists of 18 members. SmTPSs share common ancestry with typical seed plant TPSs. Selected members of the SmTPSs were shown to encode diterpene synthases. The second type of genes, designated as S. moellendorffi [corrected] microbial TPS-like genes (SmMTPSLs), consists of 48 members. Phylogenetic analysis showed that SmMTPSLs are more closely related to microbial TPSs than other plant TPSs. Selected SmMTPSLs were determined to function as monoterpene and sesquiterpene synthases. Most of the products formed were typical monoterpenes and sesquiterpenes that have been previously shown to be synthesized by classical plant TPS enzymes. Some in vitro products of the characterized SmMTPSLs were detected in the headspace of S. moellendorffi [corrected] plants treated with the fungal elicitor alamethicin, showing that they are also formed in the intact plant. The presence of two distinct types of TPSs in the genome of S. moellendorffi [corrected] raises the possibility that the TPSs in other plant species may also have more than one evolutionary origin.
萜烯合酶（TPSs）是萜类化合物生物合成的关键酶，萜类化合物是植物和其他生物产生的最大类次生代谢物。为了了解这些酶在植物中广泛多样化的基础，我们研究了卷柏属（Selaginella moellendorffi），[更正]一种非种子维管植物。发现该物种的基因组包含两种不同类型的 TPS 基因。第一类基因，被指定为 S. moellendorffi [更正] TPS 基因（SmTPSs），由 18 个成员组成。SmTPSs 与典型的种子植物 TPSs 具有共同的祖先。选定的 SmTPSs 成员被证明编码二萜合酶。第二类基因，被指定为 S. moellendorffi [更正]微生物 TPS 样基因（SmMTPSLs），由 48 个成员组成。系统发育分析表明，SmMTPSLs 与微生物 TPSs 的亲缘关系比其他植物 TPSs 更密切。选定的 SmMTPSLs 被确定为单萜和倍半萜合酶。形成的大多数产物是以前被证明由经典植物 TPS 酶合成的典型单萜和倍半萜。用真菌诱导子阿拉霉素处理后，在卷柏属[更正]植物的头空间中检测到一些特征化的 SmMTPSLs 的体外产物，表明它们也在完整植物中形成。在 S. moellendorffi [更正]基因组中存在两种不同类型的 TPSs，这增加了其他植物物种的 TPSs 可能也有不止一个进化起源的可能性。
