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-微生物相互作用领域正在经历范式转变。从历史上看，宿主与其寄生虫、病原体和共生体之间的成对相互作用主要作为孤立的成对相互作用进行研究。现在，人们越来越认识到宿主是生态系统。单个植物或动物体内有数百甚至数千种微生物，这些微生物直接或间接通过其共同宿主相互竞争或促进。因此，人们逐渐形成共识，即生态框架对于理解宿主相关群落的组装和功能至关重要。共享同一宿主的微生物会影响彼此的定殖成功。这些模式扩展到整个宿主相关的微生物群落。微生物组操作表明，寄生虫会改变微生物组的组成，而微生物组反过来又会影响宿主的寄生虫负载或微生物共生体的定殖成功。共定殖微生物之间的串扰通常表现为优先效应，其中与一种微生物的早期相遇会影响宿主对后来定殖者的反应。遇到寄生虫或病原体后的植物会表现出更强、更快速的反应。优先效应在宿主相关社区中普遍存在。然而，相对于多寄生虫或多共生系统，共殖民共生体和寄生虫之间的优先效应仍未得到充分研究。伍德实验室最近发现，在豆科植物苜蓿中，早期到达的寄生线虫通过后来到达的固氮根瘤菌抑制结瘤，而早期到达的根瘤菌则促进虫瘿的形成。换句话说，在共定殖的宿主中，寄生虫抑制共生，而共生体则增加对寄生虫感染的易感性。这一结果具有生物学意义，因为它几乎肯定对宿主来说是适应不良的。苜蓿-根瘤菌-线虫系统是一个易于处理的实验系统，可以在其中区分基于资源和防御的机制对宿主相关群落竞争的相对贡献。对非共生宿主的受控接种很简单，因为根瘤菌和线虫都是水平传播的。我们将使用分根培养系统，将植物的根系统分成两个独立操作的盆，以理清局部和系统反应。因此，在本提案中，我们将使用遗传、生理和细胞生物学方法来检验优先效应是由宿主防御反应或宿主资源分配介导的假设。