The evolutionary genomics of infectious phytopathogen emergence

传染性病原体给全球农业造成了沉重的负担，并导致发展中国家严重的粮食短缺。这种负担大部分是由新出现的病原体造成的，这些病原体最近已经进化到对重要作物造成疾病。然而，令人惊讶的是，我们对使病原体出现并引起疫情的进化机制知之甚少。狄龙实验室的长期目标是了解新型传染病是如何通过关键致病基因（毒力因子）的多样化而出现的，以便我们能够更好地保护脆弱的作物免受破坏性病原体的侵害。为了实现这一目标，我们利用植物病原体黄单胞菌来解决以下三个目标：1。描述关键毒力因子的分布和多样化。我们将分析超过一千个基因组，以确定显示与宿主-病原体军备竞赛相关的进化特征的毒力因子。我们对在多个物种中发现的效应基因特别感兴趣，因此能够产生跨物种抗性屏障。2.功能评估毒力因子多样化在宿主-病原体相互作用命运中的作用。我们将测试候选毒力因子是否会引起植物免疫，并将结果与我们的比较基因组分析相结合，以建立宿主特异性的定量模型。3.剖析新型传染病出现的进化途径。我们将在模型宿主上实验进化三种不同的露营X.菌株，并随着时间的推移表征疾病出现的表型和遗传基础。我们还将确定与替代宿主上的疾病出现相关的进化权衡，这将揭示宿主特异性适应的后果。我们的研究将捕捉毒力因子如何在远亲病原体中传播，确定决定宿主-病原体相互作用命运的跨物种抗性因子，并首次直接洞察产生新植物疾病的进化途径。我们还将提供丰富的宿主耐药靶点的新来源，并开发用于田间的基因组病原体诊断方法。这项工作将通过为正在进行的育种和监测项目提供这些资源，直接使加拿大人受益，最终减少加拿大农民的病原体负担和加拿大消费者的下游成本。在未来的五年里，我还将为超过25名各级HQP（学士，硕士，博士，PDF）提供先进的多学科培训，以填补学术界，工业界和政府的关键角色。随着我们不断变化的气候继续创造有利于病原体成功的条件，我们将帮助建立强大的疾病控制战略，帮助改变宿主-病原体相互作用的平衡，有利于我们脆弱的作物。

Infectious pathogens impose a substantial burden on the global agricultural industry and result in major food deficits in developing nations. Much of this burden is inflicted by emerging pathogens that have recently evolved to cause disease on important crops. However, we know surprisingly little about the evolutionary mechanisms that enable pathogens to emerge and cause outbreaks. The long-term goal of the Dillon Lab is to understand how novel infectious diseases emerge through diversification of critical disease-causing genes (virulence factors) so that we can better protect vulnerable crops from devastating pathogens. In pursuit of this goal, we are leveraging the plant pathogen Xanthomonas to address the following three objectives: 1.Characterize the distribution and diversification of critical virulence factors. We will analyze more than a thousand genomes to identify virulence factors displaying evolutionary signatures associated with the host-pathogen arms race. We are particularly interested in effector genes that are found in multiple species and are thus capable of generating cross-species resistance barriers. 2.Functionally assess the role of virulence factor diversification in the fate of host-pathogen interactions. We will test whether candidate virulence factors elicit plant immunity and combine the results with our comparative genomic analysis to develop quantitative models of host specificity. 3.Dissect the evolutionary pathways through which novel infectious diseases emerge. We will experimentally evolve three different X. campestris strains on a model host and characterize the phenotypic and genetic basis of disease emergence through time. We will also identify evolutionary tradeoffs associated with disease emergence on alternative hosts, which will reveal vulnerabilities that are a consequence of host specific adaptation. Our research will capture how virulence factors are disseminated across distantly related pathogens, pinpoint cross-species resistance factors that determine the fate of host-pathogen interactions, and produce the first direct insight into the evolutionary pathways that yield the emergence of new plant diseases. We will also provide a rich new source of host resistance targets and develop genome-enabled pathogen diagnostics for use in the field. This work will directly benefit Canadians by contributing these resources to ongoing breeding and surveillance programs, ultimately reducing the burden of pathogens on Canadian farmers and the downstream costs for Canadian consumers. In the next five years, I will also provide advanced multidisciplinary training for more than 25 HQP at all levels (B.Sc., M.Sc., Ph.D., PDF) to fill critical roles in academia, industry, and government. As our changing climate continues to create conditions conducive to pathogen success, we will help build robust disease-control strategies that help shift the balance of host-pathogen interactions in favour of our vulnerable crops.