Ecological and evolutionary drivers of host-symbiont associations in the phyllosphere

叶际宿主-共生体关联的生态和进化驱动因素

• 批准号: RGPIN-2022-04343
• 负责人: Lajoie, Geneviève
• 金额: $ 2.11万
• 依托单位: Université de Montréal
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=765215
• 关键词: Ecological; evolutionary; drivers; host; symbiont

Symbiotic lifestyles are important components of microbial diversity across ecosystems. How associations with hosts are shaping microbial ecology and evolution has yet been studied most extensively for symbioses in which microbes depend on their host for survival (i.e. obligate symbioses). These studies have emphasized the importance of host association in driving the specialization of symbionts, sometimes leading to the co-diversification of symbionts with their hosts. Whether specialization is a common outcome of host association in systems where symbionts have frequent opportunities to interact with free-living habitats and diverse host species is an important frontier in the study of microbial symbioses. In the context of this proposal, I combine field observational experiments and manipulative experiments in the laboratory to address the mechanisms that drive host range in plant leaf bacteria. These investigations target three short-term objectives. For the first objective, I will determine the effect of different types of plant traits in driving the host specialization or generalization of their bacteria. By sampling bacterial communities from over 50 species of Asteraceae, I will specifically assess whether the association of leaf bacteria with multiple host species (i.e. generalization) is most constrained by variation in resource provision among hosts (e.g. leaf carbohydrate content) or by variation in the host defence compounds (e.g. phenolics). For the second objective, I will test if bacterial association with multiple host species is driven by phenotypic plasticity or by specialization on one type of resource that can be tracked among hosts. My lab will cultivate bacterial strains from plant species characterized in objective one and perform phenotypic assays to determine the influence of the identity and diversity of carbons they can metabolize on their host range. For the third objective, I will develop a novel microbial study system - herbarium specimens - to characterize long-term temporal turnover in bacterial community composition of plant leaves as a response to climate change and urbanization. Sequencing of microbes on live specimens from the same locations as the herbarium specimen will enable comparison of their composition through time. This work will involve the development of protocols for work with old bacterial DNA. Overall, I provide highly innovative and multi-faceted approaches to improve our understanding of the emergence and persistence of plant-microbe symbioses, with important consequences for predicting the fate of these relationships in changing environments.

共生生活方式是生态系统中微生物多样性的重要组成部分。与宿主的关联如何塑造微生物生态学和进化的研究最广泛地研究了微生物依赖其宿主生存的共生体（即专业共生）。这些研究强调了宿主关联在推动共生体的专业化方面的重要性，有时会导致共生体与宿主共同变化。专业化是否是宿主关联在共生体经常与自由生活栖息地和多样化寄主物种相互作用的系统中的共同结果，这是微生物共生性研究的重要边界。在该提案的背景下，我将实验室的现场观察实验和操纵实验结合在一起，以解决驱动植物叶细菌中宿主范围的机制。这些调查针对三个短期目标。对于第一个目标，我将确定不同类型的植物特征在推动其细菌的宿主专业化或概括方面的影响。通过对50多种星状科的细菌群落取样，我将特别评估叶细菌与多种宿主物种的缔合（即概括）是受宿主之间资源提供的变化（例如叶碳水化合物含量）的差异（例如，叶片碳水化合物含量）的变化，还是宿主防御化合物的变化。对于第二个目标，我将测试与多种宿主物种的细菌缔合是由表型可塑性驱动的，还是在可以在宿主之间跟踪的一种资源进行专业化。我的实验室将从物镜中表征的植物物种中培养细菌菌株并进行表型测定，以确定可以代谢宿主范围的碳认同和多样性的影响。对于第三个目标，我将开发一个新型的微生物研究系统 - 植物标本标本 - 以表征植物叶细菌群落组成中的长期时间更新，以此作为对气候变化和城市化的反应。与标本室标本相同位置的活标本上的微生物进行测序将使它们的组成通过时间进行比较。这项工作将涉及开发与旧细菌DNA合作的方案。总体而言，我提供了高度创新和多方面的方法，以提高我们对植物 - 微生物共生的出现和持久性的理解，这对于预测不断变化的环境中这些关系的命运带来了重要的后果。