Collaborative Research: Within-host Microbial Communities: Experimentally Scaling Interaction Dynamics Across Sites, Regions, and Continents

生物体内的真菌、细菌和病毒微生物群落极其多样，并编码生物圈中的绝大多数基因。例如，人体内的微生物所占的基因数量是宿主的100倍;几乎所有自由生活的生物体都出现了类似的结果。 疾病是研究得最多的宿主与微生物相互作用，但宿主体内的微生物也负责关键功能，例如抗病性、营养吸收和防御食草动物（植物）、消化和减少炎症反应（动物）。然而，尽管微生物的巨大的多样性和重要性的自由生活的有机体，有没有预测的了解的因素控制内宿主微生物群落组成或空间尺度的环境变化影响主机和微生物群落的相互作用和功能。尽管人类活动导致氮和磷输入增加，物种入侵和灭绝的速度增加，影响从个体到大陆的生物系统，但我们对这些变化对宿主内微生物群落的影响知之甚少。该奖项将首次系统地了解植物微生物群落对全球范围内这些普遍环境变化的反应，并提供有关微生物在植物生产力中的潜在作用的至关重要的信息，为养活不断增长的人口（到2050年将达到90亿）提供必要的知识。该奖项提供资金，使用前所未有的规模实验来研究控制植物宿主真菌，细菌和病毒微生物的环境因素，范围从单个植物到区域和全球生物气候和土壤梯度。使用定量模型来检查多尺度的经验数据，项目团队的工作将回答三个问题。1)在全球、大陆、区域和地方范围内，哪些因素最强烈地控制着宿主体内的微生物群落？ 2)宿主内微生物群落如何影响宿主繁殖和对致病微生物的易感性？宿主体内的共生微生物群落如何影响微生物的生长、竞争能力和成功传播？该研究将包括在六大洲的30个草原上进行的重复实验，代表全球相关的土壤养分变化。 同时收集的数据，从当地常见的草主机，以及种植作物主机（大麦）在实验营养和草食动物治疗将被用来辨别共生微生物对植物宿主健康的影响，并区分这些从其他大规模的因素，如气候和特定的微生物在每个位置。高通量测序将用于确定宿主内微生物群落的变化，范围从米到大陆。操纵性实验和数据建模将阐明微生物群落对宿主繁殖、对微生物疾病的抗性以及微生物和疾病传播的影响。更广泛的影响：草原群落覆盖了地球30%的无冰表面，并在气候条件变化很大的情况下出现。草地是重要的生态系统，为驯养和野生动物提供食物和饲料。在这项研究中，草原提供了一个实验系统，以了解驱动微生物群落组成的生态过程及其对植物宿主生长和繁殖的影响。这项工作的结果具有很大的潜力，通过阐明微生物群落在宿主健康中的作用，以及环境、空间和时间对宿主-微生物相互作用影响最大的尺度，来完善医学和农业应用。结果可能会确定新的机制，植物对作物病原体的抗性，并将大大有助于现有的微生物序列数据库链接到LTER和氖网站和优先事项。该研究小组将通过与Cedar Creek LTER和贝尔自然历史博物馆的合作，将这项工作传达给K-12儿童，本科生和公众。所有微生物数据和活培养物收藏将公开提供，进一步加强研究基础设施，并为进一步发现提供丰富的资源。与往常一样，项目PI将优先考虑代表性不足的群体的参与，并在同行评审的期刊上传播结果。

The fungal, bacterial, and viral microbial communities embedded within organisms are extremely diverse and encode the vast majority of genes in the biosphere. For example, microbes in a human account for 100 times more genes than those of their host; similar results are emerging for virtually all free-living organisms. Disease is the best studied host-microbe interaction, but microbes inside hosts also are responsible for critical functions such as disease resistance as well as nutrient uptake and defense against herbivores (plants), and digestion and reduced inflammatory responses (animals). Yet, in spite of the tremendous diversity and importance of microbes to free-living organisms, there is no predictive understanding of the factors controlling within-host microbial community composition or the spatial scales at which environmental changes affect host and microbial community interactions and functions. Even as human activities lead to increased nitrogen and phosphorus inputs and increased rates of species invasions and extinctions, impacting biological systems at scales ranging from individuals to continents, we know little of the effects of these changes on microbial communities within hosts. This award will provide the first systematic understanding of the responses of plant microbial communities to these pervasive environmental changes on a global scale and provide critically important information on the potential role of microbes in plant productivity, knowledge necessary for feeding a growing human population (9 billion by 2050). This award provides funds to use experiments of unprecedented scale to examine the environmental factors controlling a plant host's fungal, bacterial, and viral microbes at scales ranging from individual plants to regional and global bioclimatic and soil gradients. Using quantitative models to examine multi-scale empirical data, the project team's work will answer three questions. 1) What factors most strongly control microbial communities within hosts across global, continental, regional, and local scales? 2) How does the within-host microbial community affect host reproduction and susceptibility to disease-causing microbes? And 3) how do the symbiotic microbial communities within a host affect the growth, competitive ability, and successful transmission of microbes? The research will encompass replicated experiments in 30 grasslands spanning six continents, representing globally-relevant variation in soil nutrients. Concurrent collection of data from locally common grass hosts as well as a planted crop host (barley) within experimental nutrient and herbivory treatments will be used to discern the effects of symbiotic microbes on plant host health and to distinguish these from other large-scale factors such as climate and the specific microbes found in each location. High-throughput sequencing will be used to determine variation in within-host microbial communities at scales ranging from meters to continents. Manipulative experiments and data modeling will clarify the effect of microbial communities on host reproduction, resistance to microbial disease, and the spread of microbes and disease. Broader Impacts: Grassland communities cover 30% of Earth's ice-free surface, and occur across greatly varying climatic conditions. Grasslands are essential ecosystems that provide food and forage for domesticated and wild animal populations. In this research, grasslands provide an experimental system with which to understand the ecological processes driving microbial community composition and its effects on plant host growth and reproduction. Results of this work have great potential for refining medical and agricultural applications by illuminating the role of microbial communities in the health of their hosts, and the scales at which environment, space, and time most affect host-microbe interactions. Results may identify novel mechanisms of plant resistance to crop pathogens and will contribute significantly to existing microbial sequence databases linked to LTER and NEON sites and priorities. The research group will communicate this work to K-12 children, undergraduates, and the general public via collaborations with Cedar Creek LTER and the Bell Museum of Natural History. All microbial data and living culture collections will be made publicly available, further enhancing research infrastructure and providing a rich resource for further discovery. As always, the project PIs will prioritize involvement of underrepresented groups and disseminate results in peer-reviewed journals.