Understanding the molecular traits of multi-organismic communication in beneficial tree-microbe associations

在自然环境中，植物和真菌并不是孤立地生活在一起，而是不断地相互作用。他们之间的交流过程对他们互动的命运至关重要。这些通过信号化合物发生，如真菌和根部衍生的糖或挥发性有机化合物(VOC)。众所周知，植物VOCs参与了阻止草食动物或吸引捕食者，但最近更多的证据突显了VOCs在根际生态中的重要性。然而，到目前为止，大多数研究都集中在双边系统上，从而忽视了更自然、更多组织情景的复杂性。因此，更多的合作伙伴可能如何改变沟通，以及哪些是机械性的改变--特别是在建制国家--等问题远未得到理解。本提案的总体目标是破译木本寄主植物(杨树x canescens)与哈茨木霉(Trichoderma Harzianum)和外生菌根双色乳杆菌(Laccaria Biolor)等植物有益真菌之间的VOC和碳水化合物介导的信息传递。所选择的三方互动是高度相关的，因为合作伙伴都是非常常见的，共享栖息地，而且类似的互动将经常在野外发生。然而，由于木霉的生防能力以及与之相关的真菌拮抗作用，到目前为止，这种相互作用的命运完全无法预测，这使得这种相互作用成为研究共生和寄生之间物种间交流的极好模型。第一个目标是在全基因组水平上对该系统早期建立阶段涉及的物种间交流和识别的途径和分子因素进行详细的概述。随后将通过分析木霉菌的相应突变体来研究已知的候选和涉及的因素。此外，为了了解单个合作伙伴基于VOC的沟通，我们将分析关系建立状态的不稳定配置文件。最近的研究表明，杨树在检测到真菌挥发性有机化合物后，会调整其氧化还原平衡和根系构型。因此，植物内部信号在感知到来自互惠伙伴(S)的VOCs时将被进一步破译。此外，人们对丝状真菌对根挥发物的反应知之甚少。为此，我们将研究木霉菌在暴露于杨树和漆树挥发物时的生理和转录反应。通过该项目获得的知识的潜在应用是改进的概念，用于重新造林或利用木本植物和有益植物的真菌组合修复受污染的地点。重要的是，目前在真菌和植物分子生物学和生理学方面拥有深厚专业知识的小组是独一无二的，并完美地为该项目的挑战量身定做。

In natural environments, plants and fungi do not live in isolation but are in continuous interaction with each other. Communication processes between them are vital for the fate of their interactions. These occur through signaling compounds such as fungal- and root-derived sugars or volatile organic compounds (VOCs). Plant VOCs are well known to be involved e.g. in deterring herbivores or attracting predators, but recently more evidence highlights the importance of VOCs also in rhizosphere ecology. Most studies so far, however, have concentrated on bilateral systems, thereby neglecting the complexities of more natural, multi-organismic scenarios. Therefore, questions such as how additional partners might change the communication, and which the mechanistic changes are – particularly in the establishment state, are far from being understood. The overall aim of the present proposal is to decipher the VOC- and carbohydrate-mediated communication of a woody host plant (Populus x canescens) in association with per se plant-beneficial fungi represented by Trichoderma harzianum and the ecto-mycorrhiza Laccaria bicolor. The chosen tripartite interaction is highly relevant since the partners are all very common, share habitats, and similar interactions will frequently occur in the wild. However, due to the biocontrol ability of Trichoderma and the associated fungal antagonism, the fate of the interaction is completely unpredictable so far, making the interaction an excellent model to study inter-species communication between symbiosis and parasitism. The first goal is to achieve a detailed overview regarding the pathways and molecular factors involved in the inter-species communication and recognition in the early establishment phase of the system on a whole-genome level. Candidates and factors known to be involved will subsequently be studied by the analysis of corresponding mutants in Trichoderma. Moreover, to understand the VOC-based communication of the individual partners, we will analyze the volatile profiles over the establishment state of the relationship. Recently, it was shown that poplar, upon detection of fungal VOCs, adjust its redox balance and root architecture. Thus, the plant internal signaling upon perceiving VOCs from the mutualistic partner(s) will be further deciphered. Moreover, only little is known about the response of filamentous fungi to root volatiles. To this end, we will study the physiological and transcriptional response of Trichoderma upon exposure to poplar- and Laccaria-derived volatiles. Potential applications for the knowledge gained through this project are improved concepts for reforestation or phytoremediation of contaminated sites using combinations of woody plants and plant-beneficial fungi. Importantly, the current association of groups with profound expertise in fungal and plant molecular biology and physiology is unique and perfectly tailored to the challenges of this project.