Dynamic genomes and the evolution of bacterial host specificity

害虫和病原体对农业构成严重挑战，总共破坏了世界上五种最重要的粮食作物(小麦、水稻、玉米、土豆和大豆)的25%，这些作物占全球卡路里摄入量的48%。是什么决定了特定的病原体是否会在特定的宿主上引起疾病？新出现的病原体来自哪里？病原体是如何“跳”到新宿主上的？了解寄主和病原体如何相互作用不仅对保护我们的食物供应非常重要，而且为研究与病原体效应功能、宿主免疫、病原体生态和进化以及宿主-病原体共同进化相关的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袭。为了实现这一目标，我们提出了三个目标：1.研究寄主物种内和寄主物种之间的免疫多样性，方法是利用病原体效应子文库来探索近缘野生和驯化植物物种的免疫反应。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-效应器的相互作用如何影响宿主-病原体的结果和宿主特异性的进化。这项工作还将提供对病原体克服特定植物宿主免疫防御的各种不同方式的洞察。3.通过操纵与寄主转换相关的病原菌效应基因，研究寄主专一性的机制。我们还将开发使用病原体基因组数据预测感染结果的模型。这项工作将帮助我们监测新的病原体爆发，并开发保护植物免受新威胁的方法。这项研究将确定控制寄主-病原体相互作用结果的病原体效应因子和寄主抗性基因，为军备竞赛以及作物与病原体之间的机制提供基本信息，并为培育抗病作物开发新的遗传资源。我们将更好地了解植物免疫反应在作物驯化过程中的变化，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，提供对这一复杂性状的遗传结构的洞察，以及可用于快速现场监测的诊断方法。所有这些研究都将使我们能够更好地应对细菌病原体施加的无情挑战；随着全球气候变化的后果变得更加紧迫，这一威胁只会增加。

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.