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.

Chalara Ash Dieback是欧洲灰烬的毁灭性疾病，在过去的20年中，欧洲大陆和斯堪的纳维亚半岛摧毁了大量树木。它是由真菌，hymenoscyphus pseudoalbidus引起的，无性阶段是Chalara Fraxinea，因此是该疾病的常见名称。它于2012年在英国首次确定，此后在整个英国和爱尔兰的数百个地点被发现。真菌通过风和暴风树的进口来传播性孢子。ASH是一种性别物种，通过多产的种子生产来繁殖，因此在随着时间的流逝，对Chalara的抵抗力很可能会在the中发展英国人口自然选择。对于森林科学家来说，一个重要的挑战是加速这一过程，以便在几十年之内，理想情况下，灰分种群可以更快地恢复。由于引入森林病原体的行为可能是不可预测的，因此了解真菌的进化潜力很重要。本项目将研究H. pseudoalbidus的生态遗传学和进化潜力，即真菌中遗传变异的方式与自然环境及其响应自然选择发展的能力有关。我们将获取有关真菌种群生物学的四个关键方面的信息，这些方面可用于商业和天然灰分种群的繁殖和管理。首先，我们将调查伪藻类种群中营养兼容性（VC）组的分布在英国。许多真菌使用VC作为自我/非自我识别系统，因此当遗传上不同的人相互遇到时，它们之间会形成障碍，这在很大程度上阻止了每个人入侵另一个人所占据的领土。 VC屏障的另一个重要特征是，它们抑制真菌彼此传播双链RNA病毒。研究VC组的空间分布和两种交配类型的研究将使我们能够评估DSRNA病毒在H. pseudoalbidus种群中建立的潜力，从而有助于减弱Chalara的流行。由两种类型的DNA标记确定的假碱中遗传变异的变异。由于真菌似乎是一种具有生态义务的病原体，完全取决于其宿主完成其生命周期，因此自然选择最有可能发生在宿主组织中。我们将估计伪藻群局部局部人群的遗传多样性水平以及种群之间的变化。这将使我们能够了解被风和进口树木散布的真菌种群多样化。然后，我们将研究生命周期不同阶段树木内的遗传多样性。这将为您的宿主内的真菌对自然选择的运作提供见解。三分之二，我们将研究与致病性和伪阿尔匹氏菌的生命周期有关的性状变化。这些信息对于理解自然选择会导致真菌在自然环境中发展的方式至关重要。这对于耐抗灰树也很重要，因为如果较高的致病性涉及对真菌的生殖适应性的成本，则应在灰树的种群中更广泛地建立抗性。 H.伪阿尔匹杜斯（H. pseudoalbidus）到与密切相关的真菌H. albidus，该真菌自19世纪以来就在英国闻名，并不被视为有害的病原体。特别是，我们的研究将旨在了解为什么H. pseudoalbidus比H. albidus更具侵略性的寄生虫，以及将DSRNA病毒从H. albidus转移到H. pseudoalbidus的潜力，可能导致下降查拉拉的流行。

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

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

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