Factors driving the distribution and diversity of protistan plant pathogens in grasslands and forests of the Biodiversity Exploratories (PATHOGEN)

植物-微生物相互作用被认为是植物多样性和群落组成的主要驱动力。卵菌（如腐霉属）和尾虫寄生虫（如疟原虫属）含有一些最具破坏性的普遍存在的植物病原体。除了农作物外，它们还在广泛的宿主中定殖，并可能对自然植物群落的多样性产生重要但未知的影响。尽管其功能的重要性，它们在自然栖息地的分布从来没有被系统地研究。分子环境测序允许以前所未有的细节直接调查土壤中微生物病原体的多样性和分布。我们计划评估的多样性和两组原生生物，卵菌纲和Cercozoa的天然水库，在所有300个草地和森林的生物多样性探索实验室的实验地块（EP）的土壤和根际样品从下面的子项目，使用高通量Illumina测序。这两组原生生物功能多样，跨越了一系列兼性和强制性寄生虫的自由生活的食菌动物，与一些寄生类群花费的一部分，他们的生命周期的saprotrophs。生物多样性探索提供了一个机会，研究土地利用集约化对植物寄生虫及其在德国不同地理区域的自由生活亲属的影响。网络分析将被应用于识别i）微生物群落中的中心相互作用植物病原体（即枢纽），ii）潜在的抑制性土壤群落，以及iii）它们与来自根分泌物和植物性状的代谢物的关系。这将是第一个大规模的研究，以揭示这些高度多样化和功能重要的原生生物在自然栖息地的分布。本研究将有助于确定抑制植物寄生虫的管理措施，并对病原体爆发的情况提供提示。

Plant-microbe interactions are considered the main drivers of plant diversity and community composition. Oomycetes (eg Pythium) and cercozoan parasites (eg Plasmodiophora) contain some of the most destructive ubiquituous plant pathogens. Apart from crop plants, they colonize a wide range of hosts and potentially have an important but yet unknown impact on the diversity of natural plant communities. In spite of their functional importance, their distribution in natural habitats has never been systematically studied. Molecular environmental sequencing allows investigating in unprecedented details the diversity and distribution of microbial pathogens directly in soil. We plan to assess the diversity and natural reservoirs of two groups of protists, the Oomycetes and Cercozoa, in soils of all 300 grassland and forest experimental plots (EPs) of the Biodiversity Exploratories and in rhizosphere samples from the BELOW subproject, using high-throughput Illumina sequencing. These two groups of protists are functionally diverse, spanning a range of facultative and obligatory parasites to free-living bacterivores, with some parasitic taxa spending part of their life cycle as saprotrophs. The Biodiversity Exploratories offer the opportunity to study the effects of land-use intensification on plant parasites and their free-living relatives in different geographic regions of Germany. Network analyses will be applied to identify i) central interacting plant pathogens (i.e. hubs) in microbial communities, ii) potential suppressive soil communities, and iii) their relationships to metabolites from root exudation and plant traits. This will be the first large-scale study to reveal the distribution of these highly diverse and functionally important protist in natural habitats. This study will help identifying the management practices suppressing plant parasites and give hints on the circumstances of pathogen outbreaks.