Recognition, signalling and response of the diatom Fragilariopsis to epibiotic bacterial colonization.

硅藻脆弱菌对表生细菌定植的识别、信号传导和反应。

• 批准号: 442925794
• 负责人: Professor Dr. Tilmann Harder
• 金额: --
• 依托单位: Arbeitsgruppe Neurobiochemistry
• 依托单位国家: 德国
• 项目类别: Infrastructure Priority Programmes
• 财政年份: 2020
• 资助国家: 德国
• 起止时间: 2019-12-31 至 2023-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/442925794?language=en
• 关键词: Recognition; signalling; response; diatom; Fragilariopsis

The diatom Fragilariopsis dominates phytoplankton in the Southern Ocean and plays a central role in the significant (15% of global) primary productivity of Antarctic regions. Marine primary production is fuelled by spatially close interactions between microalgae and bacteria and driven by their reciprocal needs for essential trace elements, micro- and macro-nutrients. Several recent microbiome studies of diverse phytoplankton species suggest that they harbour unique microbiomes, which are consistent and specific within phytoplankton species and across temporal scales. Yet, the mechanistic processes causing these associations at different levels of specialization are poorly understood.The main hypothesis addressed in this proposal postulates that Fragilariopsis relies on, or employs comparable recognition and transduction strategies in response to environmental bacteria as animals and plants, despite their phylogenetic distance to the diatom. Thus, in theory this analogy allows a cross-disciplinary transfer of methodology from well investigated immunity and microbiome science in animals and plants to a phytoplankton species.The concept of active recognition, selection and filtering processes, which supposedly steer the assembly of Fragilariopsis-associated microbiomes, is well understood in the context of immunity in multicellular organisms, even in multicellular marine macroalgae, but not in diatoms. Such responses are triggered via receptor-mediated recognition of bacterial elicitors and mediated by well-investigated signaling cascades (e.g. via nitric oxide (NO)). As a consequence, this leads to the upregulation of a variety of quantifiable stress markers, such as intracellular reactive oxygen species or a shift of the glutathione to glutathione-disulfide ratio. Partially, these stress markers have been verified in microalgae and first evidence of NO signaling and NO synthase-like gene sequences in marine diatoms is emerging. This proposal thus addresses pertinent DFG SPP questions, such as the need of “improved understanding of polar processes and mechanisms'' and the “response [of SO organisms] to environmental change”. Specifically, we will isolate, culture and identify various bacteria from Fragilariopsis microbiomes. In parallel, different Fragilariopsis ecotypes are axenified. In co-culture assays, we will employ known and well established chemical and molecular tools to characterize and quantify intra- and extracellular responses of Fragilariopsis to bacteria and bacterial molecular elicitors, such as bacterial lipopolysaccharides.The short term goal of this proposal is to corroborate an active response of Fragilariopsis to bacteria or bacterial signaling molecules. The long-term goal of this work is to analyse the holobiont assembly and challenge the recognition process by experimentally adjusting future SO climate regimes to understand the susceptibility of the Fragilariopsis holobiont to predicted climate change scenarios.

硅藻脆性果在南海中占主导地位，在南极地区的重要（全球）主要产量（占全球15％）中的核心作用。海洋初级生产是由微藻与细菌之间的空间紧密相互作用助长的，并取决于它们对基本痕量元素，微量和宏观营养素的相互需求。最近对潜水浮游植物物种的微生物组研究表明，它们具有独特的微生物组，它们在浮游植物物种中既一致且特异性，又在临时尺度上具有特异性。然而，对引起不同专业水平的这些关联的机械过程知之甚少。该提案中提到的主要假设假设frabilariopsis依赖于依赖的脆弱性，或者，员工响应环境细菌作为动物和植物，dospite的识别和翻译策略可比较，dospite dospite对diatom的系统发育距离。从理论上讲，这种类比允许从精心研究的动物和植物中的免疫学和微生物组科学转移到浮游植物物种中。积极识别，选择和过滤过程的概念，据说可以使脆弱的微生物群在多个杂种中得到充分了解，从而使脆弱的微生物群在多个机构中得到充分了解。大藻，但不在硅藻中。这种反应是通过受体介导的对细菌引起的识别的识别而触发的，并由对信号良好的信号级联反应（例如，通过一氧化氮（NO））介导。结果，这导致了各种可量化的应力标记物的上调，例如细胞内活性氧或谷胱甘肽与谷胱甘肽 - 二硫化物比率的转移。部分地，这些应力标记已在微藻中得到验证，并且在海洋硅藻中没有信号传导和没有合酶的基因序列的第一个证据正在出现。因此，该提案解决了相关的DFG SPP问题，例如需要“提高对极地过程和机制的理解”以及“ [So有机体]对环境变化的反应”。具体而言，我们将分离，培养并鉴定出从脆弱的微生物组中进行各种细菌。同时，不同的脆性生态型被轴心化。在共培养测定中，我们将采用已知且建立的化学和分子工具来表征和量化脆性细菌和根部分子引起的脆性和细胞外反应，例如细菌脂多糖。该提议的简短目标是证明脆弱的分子的活跃反应。这项工作的长期目标是分析Holobiont组装，并通过实验调整未来，从而挑战识别过程，从而使气候制度了解Fragilariopsis Holobiont对预测气候变化情景的敏感性。