Monoterpenoid Pheromone Production in Coleoptera: Characterization of Geranyl Diphosphate Synthase

鞘翅目昆虫是美国最具破坏性的害虫之一。在北美，树皮甲虫每年造成数十亿立方英尺针叶直立木材的损失。棉铃象鼻虫Anthonomas grandis造成的年平均产量损失和控制成本超过3亿美元。树皮甲虫和棉铃象鼻虫在动物中是独一无二的，因为它们都能产生单萜烯和C10信息素成分，这是交配和繁殖所必需的。该项目的长期目标是基于昆虫信息素系统开发新的有效的害虫管理策略。为了从管理的角度充分利用信息素介导的树皮甲虫和棉铃象鼻虫行为，深入了解这些信号的来源、表达和活性是很重要的。Blomquist/Tittiger实验室最近的研究表明，雄性松雕刻甲虫Ips pini可以重新合成ipsdienol，其合成受幼体激素（JH）的控制，该激素可诱导3-羟基-3-甲基戊二酰辅酶a还原酶（HMG-R）和hmg -辅酶a合成酶（HMG-S）的转录水平。单萜类信息素产生的另一个关键酶是香叶二磷酸合成酶（GPPS），它控制类异戊二烯产物的链长。研究人员建议进一步了解该酶的活性调控与信息素产生的关系，并对该酶进行克隆、测序和建模。这些研究在类异戊二烯生物化学和基础昆虫分子生物学方面具有重要意义。植物单萜类化合物的合成完全通过非甲羟戊酸途径，这使得Ips和A. grandis成为研究以甲羟戊酸为基础的单萜类生物合成调控的相对新颖的系统。此外，很少有其他昆虫模型研究异戊二酯二磷酸合成酶的分子生物学，而且这些模型都没有涉及GPPS或建模研究。此外，这些其他模型都没有单萜类终产物，可以很容易地以毫克的量回收，就像I. pini和a . grandis的情况一样。最后，Ips pini和a . grandis信息素的生物合成，特别是关键类异戊二烯酶的转录，代表了研究JH调控基因表达的非发育模式系统。这项工作建立并扩展了在Blomquist/Tittiger实验室进行的昆虫信息素调节的分子生物学研究的开创性工作。

Insects in the order Coleoptera are among the most destructive pests in the United States. Bark beetles are responsible for losses of billions of cubic feet of coniferous standing timber each year in North America. The cotton boll weevil Anthonomas grandis accounts for over $300 million average annual yield loss and control costs. The bark beetles and the boll weevil are unique among animals in that both produce monoterpenes, C10 pheromone components that are required for mating and reproduction. The long term goal of this project is to develop new and effective pest management tactics based on insect pheromone systems. To fully exploit pheromone-mediated bark beetle and cotton boll weevil behavior from a management standpoint, a thorough understanding of the origin, expression and activity of these signals is important. Recent work in the Blomquist/Tittiger laboratory has demonstrated that the male pine engraver beetle, Ips pini, synthesizes ipsdienol de novo, and that production is controlled by juvenile hormone (JH) which induces 3-hydroxy-3-methylglutaryl-CoA reductase (HMG-R) and HMG-CoA synthase (HMG-S) transcript levels. Another key enzyme in monoterpenoid pheromone production is geranyl diphosphate synthase (GPPS), which controls the chain length of the isoprenoid product. Work is proposed to gain an understanding of the regulation of the activity of this enzyme in relationship to pheromone production and to clone, sequence and model the enzyme. The studies outlined in this proposal are significant because of their impact on isoprenoid biochemistry and basic insect molecular biology. It is becoming clear that plant monoterpenes are synthesized entirely via the non-mevalonate pathway, making Ips spp. and A. grandis relatively novel systems for the study of the regulation of mevalonate-based monoterpenoid biosynthesis. Furthermore, there are few other insect models in which the molecular biology of isoprenyl diphosphate synthases have been studied, and none of these have involved GPPS or modeling studies. Also, none of these other models has a monoterpenoid end product that can be readily recovered in mg quantities as is the case with I. pini and A. grandis. Finally, Ips pini and A. grandis pheromone biosynthesis, and specifically the transcription of key isoprenoid enzymes, represents a non-developmental model system for the study of JH regulated gene expression. This work builds upon and expands the pioneering work on the molecular biological studies of insect pheromone regulation performed in the Blomquist/Tittiger laboratories.