Regulation of Monoterpene Emission in Snapdragon Flowers

花香通过吸引传粉者进入花朵，在高等植物的生殖周期中发挥着至关重要的作用。这项研究的长期目标是填补我们在导致花挥发性物质形成的生化途径以及控制其在植物中积累和释放的分子机制方面的重要知识空白。虽然单萜是天然产物萜类家族的C10成员，是花香的常见成分，但人们对花组织如何调节其发育和节律释放知之甚少。本项目将重点研究单萜生物合成的关键前体香叶基焦磷酸(GPP)在调节反式-b-罗勒烯和月桂烯的发育和节律性排放中的作用。反式-b-罗勒烯和月桂烯是骁龙香水的两种主要香味成分。GPP是许多单萜最终产物合成的起点，是二甲基烯丙基二磷酸和异戊烯基二磷酸在GPP合成酶(GPPS)催化下缩合的结果。植物细胞有两条不同的IPP生物合成途径，位于两个不同的隔间。在金鱼草花瓣组织中导致GPP生物合成的生化途径(S)将被阐明，并将通过胞质和胞质IPP池之间的交换来检验其中一条途径被另一条途径补偿的可能性。与其他同源二聚体短链戊烯基转移酶不同，GPPS是一种功能性异二聚体，其中大小亚基是酶活性所绝对需要的。在这个项目中，我们将描述骁龙中GPPS基因家族的复杂性，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调节GPPS活性中的参与。花香在农作物经济中扮演着重要的角色，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。授粉不仅影响作物产量，而且影响作物生产的质量和效益。这项研究将为高等植物香气产生的调控提供新的见解，并为工程植物改善香气质量提供知识。这可能会增加花朵对某些传粉者的吸引力，并导致为其种子、饲料或食用价值而种植的农作物更有效地授粉。

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.