Sebacinales community structure in roots and soils along land use gradients of the German Biodiversity Exploratories

鉴于人们越来越认识到土壤生物群在植物群落组成和生态系统功能中起着至关重要的作用，了解植物-土壤真菌相互作用在自然和管理植物群落中的作用具有特别重要的意义。担子菌科（Basidiomycota）真菌目最近通过基于DNA的方法显示，在全球大量陆地植物的根中存在无症状内生菌。尽管分布广泛，但对这些内生Sebacinales的生态学、群落结构以及受植物群落组成和土地利用成分的影响知之甚少。这可能是由于它们在植物根系中的丰度较低，这使得应用最近发表的特异性PCR引物成为必要。已发表的数据和我们的初步工作表明，一个根片段内的Sebacinales群落物种非常贫乏。然而，这一发现也可能是桑格测序应用的方法学上的产物。因此，我们将对一小部分样本进行大规模平行测序（454测序），以测试我们是否可以验证这些发现。已发表的系统的内生油脂碱属植物多样性评估仍然非常缺乏，其群落组成、环境因素和寄主植物特性之间的联系在很大程度上是未知的。由于在样地基础上收集了大量的生物多样性和土壤数据，生物多样性探索将是揭示这些联系的理想选择。本研究拟对各草原EP的代表性根样中皮脂草属植物群落进行分析。将分析社区数据与土地利用、土壤和植物群落特征的关系。我们预计pH等土壤参数会产生强烈的影响，增加土地利用强度会对丰富度产生负面影响，而寄主植物群落组成的影响较弱，因为寄主特异性较低。由于缺乏关于皮脂草属植物的土壤阶段、丰富度、多样性和潜在影响这些属性的因素的信息，我们建议从所有草地EP土壤样品和根样品中平行研究皮脂草属植物的群落。我们将验证土壤中发现的Sebacinales真菌实际上是根中发现的Sebacinales的“生物储存库”的假设，表明土壤阶段是主要的传播途径。我们还将测试土地利用、土壤性质和植物群落组成对土壤中发现的Sebacinales群落的影响。了解油棕属植物的土壤相将对油棕属植物生态学和土壤真菌生态学的认识产生巨大的影响。由于它们的寄主特异性较低，Sebacinales可能在植物物种之间形成共同的真菌网络中发挥重要作用，这可能对植物群落产生深远的影响，例如在植物-植物交流方面。

Understanding the effects of plant-soil fungal interactions in natural and managed plant communities is of special importance given the increasing awareness that soil biota play a crucial role in plant community assembly and ecosystem functioning. The fungal order of the Sebacinales (Basidiomycota) was recently shown to be present as symptomless endophytes in roots of a vast number of land plants globally by DNA based methods. Despite this wide distribution, very little is know about the ecology of these endophytic Sebacinales, their community structure, and how it is affected by plant community composition and components of land use. This is potentially due to their low abundance in plant roots, which make the application of recently published specific PCR primers necessary.Published data and our preliminary work suggests that Sebacinales communities within one root fragment are very species poor. However, this finding might also be a methodological artifact of the Sanger sequencing applied. We will therefore apply massive parallel sequencing (454 sequencing) on a small set of samples to test whether we can verify these findings.Published systematic diversity assessments of endophytic Sebacinales are still extremely scarce and links between their community composition, environmental factors and host plant characteristics are largely unknown. Due to the large amount of organismic diversity and soil data collected on plot basis, the Biodiversity Exploratories would be ideal to unravel these links. We propose to analyze Sebacinales communities in representative root samples from each grassland EP. Community data will be analyzed for relationships with land use, soil and plant community characteristics. We expect strong effects of soil parameters like pH, negative effects on richness by increasing land use intensity and weak effects of host plant community composition due to low host specificity. Due to the lack of information on the soil phase of Sebacinales, its richness, diversity and factors potentially shaping those attributes, we propose to study Sebacinales communities from soil samples from all grassland EP taken in parallel to the root samples. We will test the hypothesis that Sebacinales fungi found in the soil are in fact the "biological reservoir" for Sebacinales found in the root, indicating the soil phase as the major dispersal pathway. We will also test for effects of land use, soil properties and plant community composition on the Sebacinales communities found in the soil. Knowledge on the soil phase of Sebacinales will have huge implications for the understanding of Sebacinales ecology and soil fungal ecology in general. Due to their seemingly low host specificity, Sebacinales could be important in forming common fungal networks between plant species which can have profound consequences for plant communities, e.g. in terms of plant-plant communication.