Genomics and Biochemistry of Spruce Defense against Insects

针叶树是加拿大森林景观的主要树种。 它们也是林业中最重要的经济树种。然而，随着气候变化，针叶林健康越来越受到森林害虫爆发的威胁。针叶树对昆虫的天然防御的先进知识对于育种计划至关重要，以提高树木的抵抗力。 针叶树已经进化出复杂的自然防御系统，包括化学防御和物理屏障的组合。松脂的生物合成和积累是针叶树抵御昆虫的主要途径。油树脂由数百种不同的生物活性分子组成，称为萜烯。不同针叶树种之间和同一树种内部的松脂组成差异很大。两大类针叶树基因和它们的酶，萜烯脱氢酶和细胞色素P450，产生巨大的多样性和可变性的松脂萜烯。 油树脂萜烯在形成树脂导管解剖结构的专门细胞类型中生物合成。树脂道的发展和萜烯的生物合成发生的组成和昆虫诱导的防御。树脂道、萜烯和其他防御物质为针叶树抵御大多数昆虫提供了强有力的保护。然而，在爆发期间，一些高度破坏性的害虫可能会克服这些防御。 拟议的项目建立在我的长期和国际领先的研究计划的基础上（i）针叶树基因组学，（ii）针叶树防御和（iii）萜烯生物合成。我的计划的长期目标是开发一个基因组学知情的，复杂的针叶树防御系统与森林健康的应用程序的全面理解。 该项目的重点是云杉，这是加拿大重新造林最多的针叶树，以及它们的两种主要害虫（象鼻虫和芽虫）。云杉育种计划确定了对这些害虫具有抗性或耐受性的独特基因型。然而，许多潜在的防御机制及其基因组基础仍有待发现。 三个具体目标是：（1）全面解释萜烯防御的化学多样性和可塑性;（2）发现诱导萜烯生物合成的分子机制;（3）发现解释与昆虫抗性相关的独特代谢表型的基因组和生化机制。在这些目标下的研究，合作和交流提供了特殊的研究生培训机会。 该项目将使用我们在针叶树基因组学方面领先的技术平台和数据资源。它将解决长期存在的问题和针叶树防御系统的关键组成部分的新假设。它将提供有关针叶树抗性的先进基础知识，并与树木育种计划合作，为实际应用提供信息。

Conifers are the dominant trees of the Canadian forest landscape. They are also the most economically important trees for the forest industry. However, with climate change, conifer forest health is increasingly threatened by outbreaks of forest insect pests. Advanced knowledge of conifers' natural defenses against insects is essential for breeding programs to deliver trees with improved resistance. Conifers have evolved complex natural defense systems, which include combinations of chemical defenses and physical barriers against insects. Biosynthesis and accumulation of oleoresin is a major conifer defense against insects. Oleoresin consists of hundreds of different bioactive molecules, known as terpenes. Oleoresin composition is highly variable between different conifer species and within the same species. Two large classes of conifer genes and their enzymes, terpene synthases and cytochrome P450s, generate the enormous diversity and variability of oleoresin terpenes. Oleoresin terpenes are biosynthesized in specialized cell types that form the anatomical structures of resin ducts. Resin duct development and terpene biosynthesis occur as constitutive and insect-induced defenses. Resin ducts, terpenes, and other defenses provide strong protection for conifers against most insects. However, during outbreaks some highly destructive pests may overcome these defenses. The proposed project builds on the foundation of my long-term and internationally leading research program on (i) conifer genomics, (ii) conifer defense and (iii) terpene biosynthesis. The long-term goal of my program is to develop a genomics-informed, comprehensive understanding of complex conifer defense systems with applications in forest health. The project focuses on spruces, which are the most reforested conifer trees in Canada, and two of their major pests (weevils, budworms). Spruce breeding programs identified unique genotypes that are resistant or tolerant to these pests. However, much of the underlying defense mechanisms and their genomic underpinnings remain to be discovered. The three specific objectives are to (1) Comprehensively explain the chemical diversity and plasticity of terpene defenses; (2) Discover molecular mechanisms of induced terpene biosynthesis; and (3) Discover genomic and biochemical mechanisms that explain unique metabolic phenotypes associated with insect resistance. The research, collaborations and communications under these objectives provide exceptional graduate student training opportunities. The project will use our leading technology platforms and data resources in conifer genomics. It will address long-standing questions and new hypotheses on critical components of conifer defense systems. It will deliver advanced fundamental knowledge on conifer resistance and inform practical applications in collaborations with tree breeding programs.