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

鉴于人们日益认识到土壤生物群在植物群落组装和生态系统功能中起着至关重要的作用，了解自然和管理植物群落中植物-土壤真菌相互作用的影响具有特别重要的意义。担子菌目(Sebacinales)的真菌目最近被证明是以无症状的内生菌的形式存在于全球大量陆地植物的根部。尽管分布广泛，但人们对这些内生塞巴氏菌的生态、群落结构以及植物群落组成和土地利用成分的影响知之甚少。这可能是因为它们在植物根中的丰度较低，这使得应用最近公布的特异性PCR引物是必要的。公布的数据和我们的初步工作表明，一个根片段中的Sebacinales群落物种非常贫乏。然而，这一发现也可能是Sanger测序应用的方法论产物。因此，我们将对一小部分样本进行大规模的平行测序(454测序)，以测试我们是否可以验证这些发现。已发表的内生塞巴尼亚目系统多样性评估仍然极其稀少，它们的群落组成、环境因素和寄主植物特征之间的联系在很大程度上是未知的。由于以地块为基础收集了大量的生物多样性和土壤数据，生物多样性探索实验室将是揭示这些联系的理想选择。我们建议分析每个草原EP中具有代表性的根部样本中的Sebacinales群落。将分析群落数据与土地利用、土壤和植物群落特征的关系。我们预计，土壤参数如pH的影响很大，增加土地利用强度对丰富度有负面影响，寄主植物群落组成的影响较弱，因为寄主专一性较低。由于缺乏关于Sebacinales的土壤相、其丰富度、多样性以及可能影响这些属性的因素的信息，我们建议从所有草原EP的土壤样本中与根样本平行采集来研究Sebacinales群落。我们将验证在土壤中发现的Sebacinales真菌实际上是在根中发现的Sebacinales的“生物储存库”的假设，表明土相是主要的传播途径。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。对塞巴菌目土壤相的了解将对理解塞巴氏目生态学和土壤真菌生态学具有巨大的意义。由于其似乎较低的寄主专一性，Sebacinales可能在植物物种之间形成共同的真菌网络方面发挥重要作用，这可能会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.