Dynamic genomes and the evolution of bacterial host specificity

害虫和病原体对农业构成了严重的挑战，它们共同摧毁了世界上五种最重要的粮食作物（小麦、水稻、玉米、土豆、大豆）的25%，而这些作物占全球卡路里摄入量的48%。是什么决定了特定病原体是否会在特定宿主上引起疾病？新出现的病原体来自哪里？病原体是如何“跳跃”到新的宿主上的？了解宿主和病原体如何相互作用不仅对保护我们的食物供应很重要，而且为研究病原体效应作用、宿主免疫、病原体生态和进化以及宿主-病原体共同进化等基本问题提供了一个非凡的系统。我们的长期目标是保护农作物免受快速进化的细菌病原体的侵害。为实现这一目标，我们提出三个目标：利用病原菌效应物文库研究宿主物种内部和宿主物种之间的免疫多样性，探索密切相关的野生和驯化植物物种的免疫应答。我们特别感兴趣的是了解免疫多样性如何受到作物驯化的影响。2. 研究效应器之间的相互作用，以确定效应器-效应器相互作用如何影响宿主-病原体结果和宿主特异性的进化。这项工作还将深入了解病原体克服特定植物宿主免疫防御的各种不同方式。3. 通过操纵与宿主转移相关的病原体效应基因来研究宿主特异性的机制。我们还将开发模型，利用病原体基因组数据预测感染结果。这项工作将有助于我们监测新的病原体爆发，并制定保护植物免受新威胁的手段。本研究将确定控制宿主-病原体相互作用结果的病原体效应因子和宿主抗性基因，为军备竞赛和作物与其病原体之间的机制提供基础信息，并为培育抗性作物开发新的遗传资源。我们将更好地了解作物驯化过程中植物免疫反应的变化，为这一过程如何影响免疫多样性的维持提供知识。我们将描述病原体适应宿主的一系列方式，为新颖性的进化提供新的理解。我们将开发预测病原体宿主特异性的模型，为这种复杂性状的遗传结构和可用于快速现场监测的诊断方法提供见解。所有这些研究将使我们能够更好地应对细菌病原体带来的无情挑战；随着全球气候变化的后果变得更加直接，这种威胁只会加剧。

Pests and pathogens pose a serious challenge to agriculture, collectively destroying ~25% of the world's five most important food crops (wheat, rice, corn, potato, soybean), which account for >48% of the global calorie intake. What determines if a particular pathogen will cause disease on a specific host? Where do newly emerged pathogens come from? How do pathogens 'jump' to a new host? Understanding how hosts and pathogens interact is not only important for protecting our food supply, but also provides an extraordinary system for studying fundamental questions related to pathogen effector function, and host immunity, pathogen ecology and evolution, and host-pathogen co-evolution. Our long-term objective is to protect crop plants from rapidly evolving bacterial pathogens. To achieve this goal we propose three objectives: 1. Study immunodiversity within & between host species by using a library of pathogen effectors to probe for immune responses in a collection of closely related wild and domesticated plant species. We are particularly interested in understanding how immunodiversity has been impacted by crop domestication. 2. Study interactions between effectors to determine how effector-effector interactions influence host-pathogen outcomes and the evolution of host specificity. This work will also provide insight into the variety of distinct ways that a pathogen can overcome the immune defenses of specific plant hosts. 3. Investigate the mechanism underlying host specificity by manipulating pathogen effector genes that are associated with host transitions. We will also develop models to predict infection outcomes using pathogen genomic data. This work will help us monitor new pathogen outbreaks and develop means to protect plants against emerging threats. This study will identify pathogen effectors and host resistance genes that govern the outcome of host-pathogen interactions, providing fundamental information on the mechanisms underlying the arms race and between crops and their pathogens, as well as develop new genetic resources for breeding resistant crops. We will better understand how the plant immune response changes over the course of crop domestication, providing knowledge into how this process impacts the maintenance of immunodiversity. We will characterize the range of ways that a pathogen can adapt to a host, providing new understanding of the evolution of novelty. We will develop models to predict pathogen host specificity, providing insight into the genetic structure of this complex trait and diagnostic methods that could be used for rapid in-field monitoring. All of these studies will better enable us to respond to the unrelenting challenge imposed by bacterial pathogens; a threat that will only increase as the consequences of global climate change become more immediate.