Population structure and natural selection in the Chalara ash dieback fungus, Hymenoscyphus pseudoalbidus

查拉拉灰顶枯真菌 Hymenoscyphus pseudoalbidus 的种群结构和自然选择

• 批准号: BB/L01291X/1
• 负责人: James Brown
• 金额: $ 80.86万
• 依托单位: John Innes Centre
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2014
• 资助国家: 英国
• 起止时间: 2014 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FL01291X%2F1
• 关键词: Population; structure; natural; selection; Chalara

Chalara ash dieback is a devastating disease of the European ash and has destroyed large numbers of trees in continental Europe and Scandinavia over the last 20 years. It is caused by a fungus, Hymenoscyphus pseudoalbidus, of which the asexual stage is Chalara fraxinea, hence the common name of the disease. It was first identified in the UK in 2012 and has since been found at hundreds of sites throughout Britain and Ireland. The fungus spreads by dispersal of the sexual spores by the wind and by imports of diseased trees.Ash is a sexual species which reproduces by prolific seed production, so over the course of time, it is very likely that resistance to Chalara will evolve in the UK population by natural selection. An important challenge for forest scientists is to accelerate this process so that the ash population can recover more rapidly, ideally within a few decades. As the behaviour of introduced forest pathogens can be unpredictable, it is important to understand the evolutionary potential of the fungus.This project will investigate the ecological genetics and evolutionary potential of H. pseudoalbidus, i.e. the way that genetic variation in the fungus is distributed in relation to the natural environment and its capacity to evolve in response to natural selection. We will obtain information about four key aspects of the population biology of the fungus which can be applied to breeding and management of commercial and natural ash populations.First, we will investigate the distribution of vegetative compatibility (VC) groups in populations of H. pseudoalbidus in the UK. Many fungi use VC as a system of self/non-self recognition so that when genetically different individuals encounter each other, they form barriers between them which largely prevent each individual from invading the territory occupied by the other. Another important feature of VC barriers is that they inhibit fungi from transmitting doubled-stranded RNA viruses to each other. Study of the spatial distribution of VC groups and of the two mating types will allow us to assess the potential for dsRNA viruses to become established in the H. pseudoalbidus population and thus contribute to attenuating the Chalara epidemic.Second, we will study the spatial distribution of genetic variation in H. pseudoalbidus, as determined by two types of DNA marker. As the fungus appears to be an ecologically obligate pathogen which depends entirely on its host to complete its life cycle, natural selection is most likely to takes place within host tissue. We will estimate levels of genetic diversity in local populations of H. pseudoalbidus and variation between populations. This will enable us to understand how diverse are the populations of the fungus which are dispersed by the wind and on imported trees. We will then investigate genetic diversity within trees at different stages of the life cycle. This will provide insights into the operation of natural selection on the fungus within its host.Third, we will investigate variation in traits related to pathogenicity and the life-cycle of H. pseudoalbidus. This information is fundamental to understanding the way that natural selection can cause the fungus to evolve in the natural environment. It is also important for breeding resistant ash trees because if a higher level of pathogenicity involves a cost to the fungus in terms of its reproductive fitness, resistance should become established more widely in the population of ash trees.Lastly, we will investigate the relationship of H. pseudoalbidus to a closely-related fungus, H. albidus, which has known in the UK since the 19th century and is not considered a harmful pathogen. In particular, our research will aim to understand why H. pseudoalbidus is a much more aggressive parasite than H. albidus and what potential there is for dsRNA viruses to be transferred from H. albidus to H. pseudoalbidus, possibly contributing to a decline in the epidemic of Chalara.

查拉拉白蜡顶枯病是欧洲白蜡树的一种毁灭性疾病，在过去 20 年里已经摧毁了欧洲大陆和斯堪的纳维亚半岛的大量树木。它是由真菌 Hymenoscyphus pseudoalbidus 引起的，其中的无性阶段是 Chalara fraxinea，因此该疾病的俗名。它于 2012 年在英国首次被发现，此后在英国和爱尔兰的数百个地点都发现了它。这种真菌通过风传播有性孢子和进口患病树木来传播。白蜡木是一种有性物种，通过大量种子繁殖进行繁殖，因此随着时间的推移，英国种群很可能通过自然选择形成对查拉拉的抗性。森林科学家面临的一个重要挑战是加速这一过程，以便灰烬种群能够更快地恢复，最好是在几十年内。由于引入的森林病原体的行为是不可预测的，因此了解真菌的进化潜力非常重要。该项目将研究 H.pseudoalbidus 的生态遗传学和进化潜力，即真菌中遗传变异相对于自然环境的分布方式及其响应自然选择而进化的能力。我们将获得有关该真菌种群生物学的四个关键方面的信息，这些信息可应用于商业和天然灰种群的育种和管理。首先，我们将调查英国的 H.pseudoalbidus 种群中的营养相容性 (VC) 群体的分布。许多真菌使用 VC 作为自我/非自我识别系统，因此当基因不同的个体彼此相遇时，它们之间会形成屏障，在很大程度上阻止每个个体入侵另一个个体占据的领土。 VC屏障的另一个重要特征是它们抑制真菌相互传播双链RNA病毒。对 VC 群体和两种交配类型的空间分布的研究将使我们能够评估 dsRNA 病毒在 H.pseudoalbidus 群体中建立的潜力，从而有助于减轻 Chalara 流行病。其次，我们将研究 H.pseudoalbidus 遗传变异的空间分布，这是由两种类型的 DNA 标记确定的。由于真菌似乎是一种生态专性病原体，完全依赖其宿主来完成其生命周期，因此自然选择最有可能发生在宿主组织内。我们将估计 H.pseudoalbidus 当地种群的遗传多样性水平以及种群之间的变异。这将使我们能够了解通过风传播和进口树木上的真菌种群的多样性。然后我们将研究生命周期不同阶段树木的遗传多样性。这将为了解宿主内真菌的自然选择运作提供见解。第三，我们将研究与致病性和假白假丝酵母生命周期相关的性状变异。这些信息对于理解自然选择导致真菌在自然环境中进化的方式至关重要。这对于培育抗性白蜡树也很重要，因为如果更高水平的致病性会导致真菌在繁殖适应性方面付出代价，那么白蜡树种群中应该更广泛地建立抗性。最后，我们将研究 H.pseudoalbidus 与一种密切相关的真菌 H.albidus 的关系，这种真菌自 19 世纪以来在英国就已存在，不被认为是有害病原体。特别是，我们的研究旨在了解为什么假白脓杆菌是一种比白脓杆菌更具攻击性的寄生虫，以及 dsRNA 病毒从白脓杆菌转移到假白脓杆菌的可能性有多大，这可能有助于减少查拉拉流行病的发生。

项目成果

Development of a multiplex PCR assay to discriminate native Hymenoscyphus albidus and introduced Hymenoscyphus fraxineus in Britain and assess their distribution

• DOI: 10.1016/j.funeco.2016.06.002
• 发表时间: 2016-10-01
• 期刊: FUNGAL ECOLOGY
• 影响因子: 2.9
• 作者: King, Kevin M.;Webber, Joan F.
• 通讯作者: Webber, Joan F.

The ash dieback invasion of Europe was founded by two genetically divergent individuals.

• DOI: 10.1038/s41559-018-0548-9
• 发表时间: 2018-06
• 期刊: Nature ecology & evolution
• 影响因子: 16.8
• 作者: McMullan M;Rafiqi M;Kaithakottil G;Clavijo BJ;Bilham L;Orton E;Percival-Alwyn L;Ward BJ;Edwards A;Saunders DGO;Garcia Accinelli G;Wright J;Verweij W;Koutsovoulos G;Yoshida K;Hosoya T;Williamson L;Jennings P;Ioos R;Husson C;Hietala AM;Vivian-Smith A;Solheim H;MaClean D;Fosker C;Hall N;Brown JKM;Swarbreck D;Blaxter M;Downie JA;Clark MD
• 通讯作者: Clark MD

Ashes from ashes

灰烬中的灰烬

• 发表时间: 2021
• 期刊: Quarterly Journal of Forestry
• 作者: Brown JKM

The ash dieback invasion of Europe was founded by two individuals from a native population with huge adaptive potential

白蜡树顶枯病对欧洲的入侵是由来自本地种群的两个个体发起的，具有巨大的适应潜力

• DOI: 10.1101/146746
• 发表时间: 2017
• 作者: McMullan M

High frequency of vegetative incompatibility combined with haploid selfing in the native European ash foliage coloniser Hymenoscyphus albidus

• DOI: 10.1016/j.funeco.2017.04.002
• 发表时间: 2017-08-01
• 期刊: FUNGAL ECOLOGY
• 影响因子: 2.9
• 作者: Brasier, Clive;King, Kevin;Webber, Joan
• 通讯作者: Webber, Joan