Regulation of Monoterpene Emission in Snapdragon Flowers

花的气味在高等植物的繁殖周期中起着至关重要的作用，通过吸引传粉者到花。这项研究的长期目标是填补我们对导致植物挥发物形成的生物化学途径和控制其在植物中积累和释放的分子机制的认识中的重要空白。单萜类化合物是萜类化合物家族的C10成员，是花香的重要组成成分，但花的组织如何调控它们的发育和节律性散发却知之甚少。本项目将重点研究单萜生物合成的关键前体--焦磷酸香叶酯（GPP）对金鱼草香气的两种主要香气成分--反式-b-罗勒烯和月桂烯的发育和节律性释放的调节作用。GPP是合成许多单萜终产物的起始点，是二甲基烯丙基二磷酸和异戊烯基二磷酸（IPP）在GPP合酶（GPPS）催化的反应中缩合的结果。植物细胞具有位于两个不同隔室中的两个不同IPP生物合成途径。将阐明金鱼草花瓣组织中导致GPP生物合成的生化途径，并将检查通过胞质和质体IPP库之间的交换来补偿一种途径的可能性。与其他同源二聚体短链异戊二烯基转移酶相比，GPPS是一种功能性异源二聚体，其中大小亚基是酶活性绝对需要的。本项目将对金鱼草GPPS基因家族的复杂性进行表征，分析GPPS的两个亚基在调节细胞内GPP含量中的作用，并确定亚细胞定位在GPPS活性调节中的参与。 花香在作物经济中起着重要的作用，因为我们总饮食的三分之一依赖于昆虫授粉的植物，包括大多数果树，浆果，坚果，油籽和蔬菜。土壤污染不仅影响农作物产量，而且影响农作物生产的质量和效益。这项研究将为高等植物花香产生的调控提供新的见解，也为工程植物改善香味品质提供知识。这可以增加花朵对某些授粉者的吸引力，并导致为种子、饲料或食物价值而种植的作物更有效地授粉。

Floral scent plays a vital role in the reproductive cycle of higher plants by attracting pollinators to flowers. The long-term goal of this research is to fill important gaps in our knowledge of biochemical pathways leading to the formation of floral volatiles and the molecular mechanisms controlling their accumulation and release in plants. Although monoterpenes, the C10 members of the terpenoid family of natural products, are very common constituents of floral scent, little is known about how floral tissues regulate their developmental and rhythmic emission. This project will focus on investigation of the role of geranyl pyrophosphate (GPP), the key precursor of monoterpene biosynthesis, in the regulation of developmental and rhythmic emission of trans-b-ocimene and myrcene, the two major scent components of snapdragon scent. GPP, the starting point leading to the synthesis of many monoterpene end products, is the result of condensation of dimethylallyl diphosphate and isopentenyl diphosphate (IPP) in a reaction catalyzed by GPP synthase (GPPS). Plant cells have two different IPP biosynthetic pathways located in two different compartments. Biochemical pathway(s) leading to GPP biosynthesis in snapdragon petal tissue will be elucidated and the possibility of compensation of one pathway by the other one through the exchange between cytosolic and plastidic IPP pools will be examined. In contrast to other homodimeric short-chain prenyltransferases, GPPS is a functional heterodimer in which small and large subunits are absolutely required for enzymatic activity. In this project, the complexity of the GPPS gene family in snapdragon will be characterized, the role of both subunits of GPPS in the regulation of the amount of GPP in cells will be analyzed and the involvement of subcellular localization in the regulation of GPPS activity will be determined. Floral scent plays an important role in the crop economy since one-third of our total diet depends upon insect-pollinated plants including most fruit trees, berries, nuts, oilseeds, and vegetables. Pollination not only affects crop yield but also quality and efficiency of crop production. This research will result in new insights into the regulation of floral scent production in higher plants and also provide the knowledge for engineering plants with improved scent quality. This could increase the attraction of flowers to certain pollinators and lead to the more efficient pollination of crop plants cultivated for their seed, forage, or food value.