Genomics and Biochemistry of Spruce Defense against Insects

针叶树是加拿大森林景观中的主要树木。它们也是林业最重要的经济树种。然而，随着气候变化，针叶林的健康日益受到森林病虫害的威胁。针叶树对昆虫的天然防御能力的先进知识对于培育具有更好抵抗力的树木至关重要。******针叶树进化出了复杂的自然防御系统，包括化学防御和物理屏障的结合。油树脂的生物合成和积累是针叶树抵御昆虫的主要手段。油树脂由数百种不同的生物活性分子组成，这些分子被称为萜烯。不同针叶树种之间和同一种内的油树脂成分变化很大。两大类针叶树基因及其酶萜烯合成酶和细胞色素p450产生了油脂树脂萜烯的巨大多样性和可变性。******油树脂萜烯是在形成树脂管道解剖结构的特殊细胞类型中生物合成的。树脂管道发育和萜烯生物合成发生本构性和昆虫诱导的防御。树脂管、萜烯和其他防御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，在疫情爆发期间，一些极具破坏性的害虫可能会克服这些防御措施。******提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，该计划涉及(i)针叶树基因组学，（ii）针叶树防御和（iii）萜烯生物合成。我的项目的长期目标是发展基因组学知识，全面了解复杂的针叶树防御系统与森林健康的应用。******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、budworm）。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)探索诱导萜烯生物合成的分子机制；(3)发现基因组和生化机制，解释与昆虫抗性相关的独特代谢表型。这些目标下的研究、合作和交流为研究生的培养提供了绝佳的机会。******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关于针叶树防御系统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，并为与树木育种计划合作的实际应用提供信息

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.**