22-BBSRC/NSF-BIO Hidden costs of infection: mechanisms by which parasites disrupt host-microbe symbioses and alter development

22-BBSRC/NSF-BIO 感染的隐性成本：寄生虫破坏宿主-微生物共生并改变发育的机制

• 批准号: BB/Y008782/1
• 负责人: Christine Faulkner
• 金额: $ 69.62万
• 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: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FY008782%2F1
• 关键词: 22; BBSRC; NSF; BIO; Hidden

The field of host-microbe interactions is undergoing a paradigm shift. Historically, pairwise interactions between hosts and their parasites, pathogens, and symbionts were primarily studied as isolated pairwise interactions. Now, there is increasing recognition that hosts are ecosystems. An individual plant or animal houses hundreds or even thousands of species of microorganisms that compete with or facilitate each other, either directly or indirectly via their shared host. As a result, consensus is emerging that an ecological framework is critical to understand the assembly and function of host-associated communities. Microorganisms that share the same host affect each other's colonization success. These patterns scale up to entire host-associated microbial communities. Microbiome manipulations show that parasites alter microbiome composition, and that the microbiome in turn can affect a host's parasite load or the colonization success of microbial symbionts. Crosstalk between co-colonizing microorganisms often manifests as a priority effect, in which an early encounter with one microorganism impacts the host's response to later colonizers. Plants that are primed by an encounter with a parasite or pathogen exhibit stronger and more rapid responses. Priority effects are ubiquitous in host-associated communities. Yet, relative to multiparasite or multi-symbiont systems, priority effects between co-colonizing symbionts and parasites remain understudied. The Wood lab recently found that in the legume Medicago, early arriving parasitic nematodes inhibit nodulation by later-arriving nitrogen-fixing rhizobia, while early arriving rhizobia facilitate gall formation. In other words, in co-colonized hosts, the parasite inhibits symbiosis, while the symbiont increases susceptibility to parasite infection. This result is biologically significant because it is almost certainly maladaptive for the host.The Medicago-rhizobia-nematode system is a tractable experimental system in which to discriminate between the relative contribution of resource- and defence-based mechanisms to competition in host-associated communities. Controlled inoculations onto aposymbiotic hosts is straightforward because both rhizobia and nematodes are horizontally transmitted. We will use split-root culture system, in which a plant's root system is split into two pots that are independently manipulated, to disentangle local and systemic responses. Thus, in this proposal we will use genetic, physiological and cell biological approaches to test the hypotheses that priority effects are mediated by host defence responses or alternatively by host resource allocation.

宿主 - 微杆相互作用的领域正在进行范式转移。从历史上看，宿主及其寄生虫，病原体和共生体之间的成对相互作用主要研究为孤立的成对相互作用。现在，人们对宿主是生态系统的认识越来越多。单个动植物包含数百甚至数千种微生物，它们通过其共享宿主直接或间接相互竞争或促进彼此。结果，人们的共识是，生态框架对于了解与宿主相关社区的组装和功能至关重要。共享相同宿主的微生物会影响彼此的殖民化成功。这些模式扩展到整个与宿主相关的微生物群落。微生物组的操作表明，寄生虫会改变微生物组的组成，而微生物组反过来会影响宿主的寄生虫负载或微生物共生体的定植成功。共同殖民化微生物之间的串扰通常表现为优先效应，其中一种与一种微生物的早期相遇会影响宿主对后来殖民者的反应。与寄生虫或病原体相遇的植物表现出更强，更快的反应。优先效应在与宿主相关的社区中无处不在。然而，相对于多寄生虫或多伴侣系统，共殖化的共生体和寄生虫之间的优先级影响仍在研究中。伍德实验室最近发现，在豆科植物中，早期到达的寄生线虫通过以后的固定氮根性根瘤菌抑制结节，而早期到达根瘤菌则促进了胆囊形成。换句话说，在共同殖民的宿主中，寄生虫抑制共生，而共生体增加了对寄生虫感染的敏感性。该结果具有生物学意义，因为它几乎可以肯定对宿主适应不良。对凋亡宿主的控制接种是直接的，因为根瘤菌和线虫都水平传播。我们将使用分裂根系培养系统，其中植物的根系被分为两个被独立操纵的锅，以消除本地和系统的响应。因此，在此提案中，我们将使用遗传，生理和细胞生物学方法来检验假设，即优先效应是由宿主防御反应介导的，或者由宿主资源分配介导的。