Beijing Key Laboratory of Ornamental Plants Germplasm Innovation & Molecular Breeding, National Engineering Research Center for Floriculture, Beijing Laboratory of Urban and Rural Ecological Environment, Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants of Ministry of Education, School of Landscape Architecture, Beijing Forestry University, Beijing, China.
Beijing Key Laboratory of Ornamental Plants Germplasm Innovation & Molecular Breeding, National Engineering Research Center for Floriculture, Beijing Laboratory of Urban and Rural Ecological Environment, Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants of Ministry of Education, School of Landscape Architecture, Beijing Forestry University, Beijing, China; Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, Beijing Forestry University, Beijing, 100083, China.
Plant Physiol Biochem. 2020 Jun;151:391-399. doi: 10.1016/j.plaphy.2020.03.048. Epub 2020 Apr 1.
Lily, a famous cut flower with highly fragrance, has high ornamental and economic values. Monoterpenes are the main components contributing to its fragrance, and terpene synthase (TPS) genes play critical roles in the biosynthesis of monoterpenoids. To understand the function of TPS and to explore the molecular mechanism of floral scent in cultivar Lilium 'Siberia', transcriptomes of petal at different flowering stages and leaf were obtained by RNA sequencing and three unigenes related to TPS genes were selected for further validation. Quantitative real-time PCR showed that the expression level of LiTPS2 was greater than that of the other two TPS genes. Phylogenetic analysis indicated that LiTPS2 belonged to the TPSb subfamily, which was responsible for monoterpenes synthesis. Subcellular localization demonstrated that LiTPS2 was located in the chloroplasts. Furthermore, functional characterization showed that LiTPS2 utilized both geranyl pyrophosphate (GPP) and farnesyl pyrophosphate (FPP) to produce monoterpenoids such as linalool and sesquiterpenes like trans-nerolidol, respectively. Ectopic expression in transgenic tobacco plants suggested that the amount of linalool from the flowers of transgenic plants was 2-3 fold higher than that of wild-type plants. And the emissions of myrcene and (E)-β-ocimene were also accumulated from the flowers of LiTPS2 transgenic lines. Surprisingly, these three compounds were the main fragrance components of oriental lily hybrids. Our results indicated that LiTPS2 contributed to the production of monoterpenes and could effectively regulate the aroma of Lilium cultivars, laying the foundation for biotechnological modification of floral scent profiles.
百合是一种具有浓郁香气的著名切花，具有很高的观赏和经济价值。单萜类化合物是其香气的主要成分，萜烯合酶（TPS）基因在单萜类化合物的生物合成中起着关键作用。为了了解 TPS 的功能并探索栽培百合‘西伯利亚’花香的分子机制，通过 RNA 测序获得了不同花期花瓣和叶片的转录组，并选择了三个与 TPS 基因相关的 unigenes 进行进一步验证。定量实时 PCR 显示，LiTPS2 的表达水平高于其他两个 TPS 基因。系统发育分析表明，LiTPS2 属于 TPSb 亚家族，负责单萜类化合物的合成。亚细胞定位表明 LiTPS2 位于叶绿体中。此外，功能表征表明 LiTPS2 分别利用香叶基焦磷酸（GPP）和法呢基焦磷酸（FPP）来产生芳樟醇等单萜类化合物和反式橙花叔醇等倍半萜类化合物。在转基因烟草植物中的异位表达表明，来自转基因植物花朵的芳樟醇含量比野生型植物高 2-3 倍。并且，从 LiTPS2 转基因系的花朵中也积累了月桂烯和(E)-β-罗勒烯。令人惊讶的是，这三种化合物是东方百合杂种的主要香气成分。我们的结果表明，LiTPS2 有助于单萜类化合物的产生，并能有效调节百合品种的香气，为花香特征的生物技术修饰奠定了基础。
