Molecular basis of the relationship between microbiota and the plant’s immune system

该项目将确定植物免疫系统识别微生物群的原则，并评估免疫在宿主微生物群中的作用。真核生物健康的许多方面都是宿主与其生物环境中的微生物形成的密切联系。植物能够容忍甚至促进与有害或有益微生物的关联，同时保留防御微生物病原体的能力。微生物群的存在代表了一种长期的微生物负荷，可以激发持久的免疫刺激。植物免疫是在感知病原体时触发的。与动物Toll样受体（TLR）一样，植物免疫受体识别存在于细菌家族中的细菌分子模式。植物免疫的诱导以急性的、短暂的和中度的、持续的防御为特征。植物免疫系统如何感知细菌群落以及感知如何导致与微生物群的关联，但对病原体定植的免疫是一个不完全理解的过程。使用最先进的蛋白质组学方法，如元蛋白质组学和平行反应监测（PRM），我们将在群落和家族水平上定义细菌分子模式，以及宿主微生物群中存在的类型和丰度。细菌EF-Tu和鞭毛蛋白是在叶际微生物群中大量发现的分子模式，并被植物免疫系统的EFR和FLS 2受体识别，最终诱导防御以控制细菌感染。我们将揭示EF-Tu和鞭毛蛋白引发补体，其在与合成细菌群落定殖后被宿主感知，并旨在识别微生物群中发现的潜在新型分子模式。我们还将在微生物群引发补体的水平上测试诱导模式触发免疫的植物，以及免疫缺陷植物实现微生物稳态和群落组成的能力。通过感染细菌病原体，我们将评估微生物群诱导植物免疫是否是建立成功防御的关键。该项目完成后，将定义免疫感知如何在与细菌群落的长期关联中发生的原理，并导致对导致微生物稳态的免疫机制的新见解。这将为更好地理解植物-微生物组相互作用中的一个基本问题铺平道路。

This project will identify principles of microbiota recognition by the plant’s immune system and evaluate a role for immunity in hosting a microbiota.Critical to many aspects of eukaryotic health are the intimate associations hosts form with the micro-organisms of their biotic environment. Plants are able to tolerate and even promote associations with commensal or beneficial microbes while retaining the ability to defend microbial pathogens. Hosting a microbiota represents a long-term microbial load that can provoke lasting immune stimulation.Plant immunity is triggered upon sensing of pathogens. Like animal Toll-like receptors (TLRs), plant immune receptors recognize bacterial molecular patterns that are present across bacterial families. Induction of plant immunity is characterized by acute, transient and moderate, sustained defences. How bacterial communities are sensed by the plant immune system and how perception leads to association with microbiota but immunity against pathogen colonization is an incomplete understood process.Using state-of-the-art proteomics methods such as metaproteomics and parallel reaction monitoring (PRM), we will define at a community and family level the bacterial molecular patterns, and the types and abundancies present in a hosted microbiota. Bacterial EF-Tu and flagellin are molecular patterns abundantly found in the phyllosphere microbiota and are recognized by the EFR and FLS2 receptors of the plant’s immune system, eventually inducing defenses to control bacterial infection. We will reveal the EF-Tu and flagellin eliciting complement that is perceived by the host upon colonization with synthetic bacterial communities and aim at identifying potential novel molecular patterns found in microbiota. We will also test plants upon induction of pattern-triggered immunity, at the level of the microbiota eliciting complement, and plants deficient in immunity for their ability to achieve microbial homeostasis and community composition. By infecting with a bacterial pathogen, we will evaluate whether induction of plant immunity by the microbiota is critical for the establishment of successful defence.At its completion, this project will define principles how immune perception occurs in the long-term association with bacterial communities, and lead to new insight into immunity mechanisms leading to microbial homeostasis. This will pave the way for an improved understanding of a fundamental question in plant-microbiome interactions.