Genomics and Biochemistry of Spruce Defense against Insects

针叶树是加拿大森林景观的优势树种。它们也是森林业最重要的经济树种。然而，随着气候变化，针叶林的健康越来越受到森林病虫害暴发的威胁。先进的针叶树对昆虫的天然防御知识对于培育具有更高抗性的树木是必不可少的。*针叶树进化出复杂的自然防御系统，其中包括化学防御和物理屏障对昆虫的组合。松脂的生物合成和积累是针叶树对昆虫的主要防御措施。油树脂由数百种不同的生物活性分子组成，称为萜烯。不同针叶树种间和同一树种内的松脂组成差异很大。两大类针叶树基因及其酶，萜烯合成酶和细胞色素P450，产生了油树脂萜类的巨大多样性和变异性。*油树脂萜烯是在特殊的细胞类型中生物合成的，这些细胞类型形成了树脂导管的解剖结构。树脂管的发育和萜烯的生物合成作为结构性防御和昆虫诱导防御发生。树脂管、萜烯和其他防御物为针叶树提供了强大的保护，使其免受大多数昆虫的侵害。然而，在暴发期间，一些极具破坏性的害虫可能会克服这些防御。*我的长期和国际领先的研究计划(I)针叶树基因组学，(Ii)针叶树防御和(Iii)萜烯生物合成的基础上提出的项目。我的计划的长期目标是发展一种对复杂的针叶树防御系统及其在森林健康中的应用的基因组学知识的全面理解。*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、小虫子)。云杉育种计划确定了对这些害虫具有抗性或耐性的独特基因类型。然而，许多潜在的防御机制及其基因组基础仍有待发现。这三个具体目标是：(1)全面解释萜类防御的化学多样性和可塑性；(2)发现诱导萜类生物合成的分子机制；(3)发现解释与抗虫性相关的独特代谢表型的基因组和生化机制。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的领先技术平台和数据资源。它将解决关于针叶树防御系统关键组成部分的长期存在的问题和新的假设。它将提供有关针叶树抗性的先进基础知识，并在与树木育种计划的合作中提供实际应用。**

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.**