Retaining the Ashes: The potential for ash populations to be restored following the dieback epidemic

保留灰烬：枯死流行后灰烬数量恢复的潜力

• 批准号: BB/R018618/1
• 负责人: James Brown
• 金额: $ 64.94万
• 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: 2018
• 资助国家: 英国
• 起止时间: 2018 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FR018618%2F1
• 关键词: Retaining; Ashes; potential; ash; populations

Ash dieback has been a destructive disease of European ash since 1992 and was first seen in the UK in 2012. The fungus which causes this disease is native to East Asia and is thought to have arrived in north-east Europe during the 1980s. The dieback epidemic has serious implications for the UK given the ecological role of ash as a keystone species in nature, its economic value as timber, its amenity value in cities and parks, and its service value in landscaping and ecosystem functions, notably reduction of flooding by reducing water run-off from fields and consolidating river and canal banks. While most trees in heavily affected areas are severely damaged, a small minority are clearly less susceptible, raising a significant hope that this genetic variation might lead to the long-term recovery of ash in the UK and Europe generally.This project aims to understand why this variation in dieback-resistance has evolved in European ash. This tree species is highly variable and the population in the UK has diverged substantially from that in continental Europe. Our hypothesis is that certain chemicals (secondary metabolites) confer resistance to damage by certain insects but increase the susceptibility of ash to dieback. As a resource for this project and for future research, we have collected 328 diverse ash genotypes from the UK, including numerous lines which have had low susceptibility to dieback even under intense disease pressure. This collection, known as JENNIFER, will be used to research the relationship between multiple traits to understand the ecological context of ash dieback.Ash trees with low susceptibility to dieback may either have partial resistance to dieback, so their leaves are less easily infected by the fungus, or have a form of growth and development which leads to lower exposure to spores of the fungus, thus promoting disease escape. Objective 1 of the project is to characterise the diversity of low susceptibility to dieback in UK ash. We will measure disease severity in replicated field trials exposed to natural infection, investigate components of resistance, estimate contributions of resistance and escape to low susceptibility, and test if genetic resistance to dieback in UK trees has diverged from that studied previously in Denmark. Small-scale methods of studying infection by the dieback fungus, developed by the project partners, greatly increase the capacity to study variation in resistance.In earlier research, low levels of iridoid glycosides, a class of secondary metabolite, were found to be associated with resistance to dieback but ash also contains many other secondary metabolites. Objective 2 is to test the hypothesis that diverse secondary metabolites in ash are associated with variation in dieback-resistance. We will use untargeted metabolite profiling to identify chemical features which most strongly discriminate infected and uninfected leaves of resistant and susceptible clones, combine metabolite and transcriptome analysis to determine the genetic basis of changes in secondary metabolites in response to infection, characterise temporal variation in levels of discriminant molecular features, and relate them to resistance in the JENNIFER panel.Objective 3 is to test the hypothesis that secondary metabolites control contrasting responses of ash to dieback and to diverse herbivorous insects. This will be done by testing if variation in dieback-resistance and levels of key metabolites are associated with variation in insect feeding, growth and reproduction, and by assessing the susceptibility of the JENNIFER ash clones to attack by invertebrates in natural conditions.

自 1992 年以来，白蜡树顶枯病一直是欧洲白蜡树的一种破坏性疾病，并于 2012 年首次在英国发现。引起这种疾病的真菌原产于东亚，据信在 20 世纪 80 年代抵达欧洲东北部。鉴于白蜡树作为自然界中主要物种的生态作用、其作为木材的经济价值、其在城市和公园中的舒适价值以及其在景观美化和生态系统功能中的服务价值，特别是减少洪水，枯萎病流行对英国产生了严重影响通过减少田地径流并巩固河流和运河岸线。虽然受影响严重地区的大多数树木都受到严重损坏，但少数树木显然不太容易受到影响，这给人们带来了很大的希望，即这种遗传变异可能会导致英国和欧洲的灰烬长期恢复。该项目旨在了解原因这种抗顶枯病的变异是在欧洲白蜡树中进化而来的。这种树种变化很大，英国的树种与欧洲大陆的树种有很大差异。我们的假设是，某些化学物质（次生代谢物）赋予对某些昆虫损害的抵抗力，但增加了灰烬对枯萎病的敏感性。作为该项目和未来研究的资源，我们从英国收集了 328 个不同的白蜡树基因型，其中包括许多即使在严重的疾病压力下也对枯萎病敏感度较低的品系。这个集合被称为 JENNIFER，将用于研究多个性状之间的关系，以了解白蜡树顶枯病的生态背景。对顶枯病敏感度较低的白蜡树可能对顶枯病有部分抵抗力，因此它们的叶子不太容易被白蜡树顶枯病感染。真菌，或具有某种生长和发育形式，导致较少接触真菌孢子，从而促进疾病逃逸。该项目的目标 1 是描述英国白蜡树对枯死病的低敏感性的多样性。我们将在暴露于自然感染的重复田间试验中测量疾病的严重程度，研究抗性的组成部分，估计抗性的贡献和逃避低易感性，并测试英国树木对顶枯病的遗传抗性是否与之前在丹麦研究的有所不同。项目合作伙伴开发的研究枯萎真菌感染的小规模方法极大地提高了研究抗性变异的能力。在早期的研究中，发现低水平的环烯醚萜苷（一类次级代谢产物）与抗枯萎病，但灰烬还含有许多其他次生代谢物。目标 2 是检验灰烬中多种次生代谢物与顶枯病抗性变化相关的假设。我们将使用非靶向代谢物分析来识别最能区分抗性和易感性克隆的感染和未感染叶子的化学特征，结合代谢物和转录组分析来确定次生代谢物响应感染而变化的遗传基础，表征判别性分子特征，并将它们与 JENNIFER 小组中的抗性联系起来。目标 3 是检验以下假设：次生代谢物控制白蜡树对枯萎病和多种植物的对比反应草食性昆虫。这将通过测试抗顶枯病和关键代谢物水平的变化是否与昆虫摄食、生长和繁殖的变化相关，并评估詹妮弗白蜡树无性系在自然条件下受到无脊椎动物攻击的敏感性来完成。

项目成果

Ashes from ashes

灰烬中的灰烬

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