Molecular analysis of arthrosporol, ascaroside and nutritional signaling during the interaction of the nematode-trapping fungus Duddingtonia flagrans with Caenorhabditis elegans

线虫捕获真菌 Duddingtonia flagrans 与秀丽隐杆线虫相互作用过程中节孢子醇、蛔苷和营养信号的分子分析

• 批准号: 501904296
• 负责人: Professor Dr. Reinhard Fischer
• 金额: --
• 依托单位: Abteilung Mikrobiologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/501904296?language=en
• 关键词: Molecular; analysis; arthrosporol; ascaroside; nutritional

Organismic interactions are crucial for live on earth. Such interactions are often very sophisticated and have been shaped during evolution. In the case of fungal interactions, they can range from symbiotic to pathogenic to predatory. We are studying nematode-trapping, predatory fungi, which produce different trapping devices, lure nematodes into the traps, invade the nematodes with penetrating hyphae and subsequently colonize the entire worm body. Our model is Duddintonia flagrans, which grows well in the lab and produces adhesive trap networks. D. flagrans is also used as a biocontrol agent in livestock farming, and may be further developed against plant pathogenic nematodes in the future. As a difference to other nematode-trapping fungi, it produces resistant chlamydospores, which may be used for its application in soil. One of the first steps of the fungal-nematode interaction is the fungal sensing of the nematodes and the initiation of trap formation. Because trap formation only makes sense, if a certain number of nematodes is present and other nutrients are not available, an interesting interorganismic communication system based on low-molecular weight compounds evolved. Trap formation is inhibited by secondary metabolites, different arthrosporols and 6-methyl salicylic acid. The fungi are able to sense ascarosides – important nematode molecules – and thereby the presence of nematodes. Ascarosides inhibit the production of the fungal-derived, negative signaling molecules, which leads to trap induction. The system resembles a quorum sensing mechanism, enabling the sensing of the nematode density.In the current research proposal, the signaling cascades underlying trap induction and morphogenesis will be analyzed. Preliminary data suggest the involvement of G-proteins and G-protein coupled membrane receptors (GPCRs) in the integration of the nutritional status and the presence of nematodes. The signaling cascades will be resolved by gene deletion and overexpression experiments. We will test the hypothesis if some fungal ascaroside-sensing GPCRs were acquired by horizontal gene transfer (HGT) from nematodes during evolution.Besides the elucidation of the components of the signaling cascades by gene deletion, gene overexpression and the use of constitutive-active G-alpha alleles, the interaction of the G-proteins with their GPCRs will be studied in time and space by bimolecular fluorescence complementation (BiFC), yeast-two-hybrid and FRET analyses.To further elucidate the process of trap induction and trap morphogenesis, target genes of the signaling cascades will be isolated and characterized after genome-wide transcription analyses.

有机相互作用对于地球上的生命至关重要。这种相互作用通常非常复杂，并且是在进化过程中形成的。就真菌相互作用而言，它们的范围可以从共生到致病到捕食。我们正在研究捕获线虫的捕食性真菌，它们产生不同的捕获装置，将线虫引诱到陷阱中，用穿透性菌丝侵入线虫，随后在整个蠕虫体内定殖。我们的模型是 Duddintonia flagrans，它在实验室中生长良好并产生粘性陷阱网络。 D. flagrans 还被用作畜牧业的生物防治剂，未来可能会进一步开发用于防治植物病原线虫。与其他捕获线虫的真菌不同，它产生抗性厚垣孢子，可用于土壤中的应用。真菌-线虫相互作用的第一步是线虫的真菌感应和陷阱形成的启动。因为陷阱的形成只有在存在一定数量的线虫且无法获得其他营养物质的情况下才有意义，因此，基于低分子量化合物的有趣的生物体间通讯系统就进化了。陷阱的形成受到次级代谢产物、不同节孢子醇和 6-甲基水杨酸的抑制。真菌能够感知蛔苷（重要的线虫分子），从而感知线虫的存在。蛔苷抑制真菌衍生的负信号分子的产生，从而导致陷阱诱导。该系统类似于群体感应机制，能够感知线虫密度。在当前的研究计划中，将分析陷阱诱导和形态发生背后的信号级联。初步数据表明，G 蛋白和 G 蛋白偶联膜受体 (GPCR) 参与营养状况和线虫存在的整合。信号级联将通过基因删除和过度表达实验来解决。我们将测试一些真菌蛔苷感应 GPCR 是否是通过线虫进化过程中的水平基因转移 (HGT) 获得的假设。除了通过基因删除、基因过表达和使用组成型活性 G-α 等位基因来阐明信号级联的组成部分之外，还将研究 G 蛋白与其 GPCR 的相互作用 通过双分子荧光互补（BiFC）、酵母双杂交和FRET分析在时间和空间上进行分析。为了进一步阐明陷阱诱导和陷阱形态发生的过程，将在全基因组转录分析后分离和表征信号级联的靶基因。