Using genomics to understand tree rust biology and epidemiology

利用基因组学了解树锈生物学和流行病学

• 批准号: RGPIN-2015-05279
• 负责人: Hamelin, Richard
• 金额: $ 2.91万
• 依托单位: University of British Columbia
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=613453
• 关键词: Using; genomics; understand; tree; rust

Tree rusts are responsible for some of the most important forest disease outbreaks in the northern hemisphere. White pine blister rust, caused by the fungal pathogen Cronartium ribicola, is an invasive alien pathogen that was introduced into North America in the late 19th century and has since spread throughout the range of distribution of white pines. This pathosystem is dynamic and new findings and observations include new hosts of the pathogen in the family Orobanchaceae, hybridization between C. ribicola and a native pine rust, a new race of C. ribicola that can overcome resistance genes in commercial black currants and new species of Cronartium on white pines in Asia. These findings have forced a reexamination of the established dogma and could impact the disease epidemic. I propose three short-term objectives to further my long-term objective of improving our understanding of the biology and epidemiology of tree rusts. 1) Elucidation of origin, patterns of dispersal, and pathways of introduction of the white pine blister rust pathogen. The hypothesis that C. ribicola originated in Asia and invaded North America via European bridgehead populations will be tested by conducting a global sampling in Europe, Asia and North America. Using genotyping by sequencing protocols established in my lab, we will generate genome scans that will be used to assess diversity and population structure of the pathogen and test and compare different scenarios of introduction. 2) Investigation of local adaptation to landscape features, hosts and climate in white pine blister rust. My hypothesis is that C. ribicola is subjected to stronger selection pressure in western North America, since it attacks more hosts, across broader conditions that include maritime, continental and alpine climates than in eastern North America and that this will be reflected in its population genomic signature. To test this hypothesis, I propose to sample C. ribicola across latitude and altitude gradients on different hosts and generate genome scans to compare the extent of positive selection and rare variants in eastern and western populations. I will then use a reverse ecology approach to identify outliers and conduct phenotypic characterization. 3) Analysis of interspecific hybridization in rusts and evaluation of its epidemiological significance. My hypothesis is that hybrid pine stem rusts will be more infectious and have a broader host range than the parental species. To test this hypothesis, I propose to measure fitness, by assessing viability, germination rates, infection potential, and reproduction of hybrid pine rusts on the different hosts, including the newly discovered hosts. By comparing pure species with hybrid rusts, we will assess whether or not these hybrids have the potential to alter white pine blister rust epidemics. Overall, this work will advance our knowledge of one of North America’s deadliest tree pathogens.

树锈病是造成北方一些最重要的森林疾病爆发的原因。白松疱锈病是由真菌病原体茶藨子生柱锈菌（Cronartium ribicola）引起的，是一种入侵性外来病原体，于19世纪末引入北美，此后在白色松的整个分布范围内传播。新的发现和观察包括列当科的新寄主、列当科与列当科之间的杂交以及列当科与列当科之间的杂交等。ribicola和一个本地松锈病，C.在亚洲的白色松树上，可以克服商业黑加仑和新品种的Cronartium的抗性基因的Ribicola。这些发现迫使人们重新审视既定的教条，并可能影响疾病的流行。我提出了三个短期目标，以促进我的长期目标，提高我们对树锈病的生物学和流行病学的理解。1)白松疱锈病病原体的起源、传播模式和传入途径的阐明。假设C.将通过在欧洲、亚洲和北美进行全球抽样，对起源于亚洲并通过欧洲桥头种群入侵北美的卷蛾进行测试。使用我实验室建立的测序方案进行基因分型，我们将生成基因组扫描，用于评估病原体的多样性和种群结构，并测试和比较不同的引入方案。2)白松疱锈病对景观、寄主和气候的适应性研究。我的假设是C. Ribicola在北美西部受到更强的选择压力，因为它在更广泛的条件下攻击更多的宿主，包括海洋性，大陆性和高山气候，而不是在北美东部，这将反映在其种群基因组特征中。为了验证这个假设，我建议对C进行采样。在不同的宿主上跨越纬度和海拔梯度对Ribicola进行研究，并生成基因组扫描，以比较东部和西部种群中的阳性选择和罕见变异的程度。然后，我将使用反向生态学方法来识别离群值并进行表型表征。3)锈菌种间杂交分析及其流行病学意义的评价。我的假设是，杂交松茎锈病将更具传染性，并有一个更广泛的主机范围比父母的物种。为了验证这一假设，我建议测量健身，通过评估的可行性，发芽率，感染潜力，并在不同的主机，包括新发现的主机上的杂交松锈病的繁殖。通过比较纯种与杂交种锈病，我们将评估这些杂交种是否有可能改变白松疱锈病的流行。总的来说，这项工作将推进我们对北美最致命的树木病原体之一的了解。