Revisiting endophytic fungi of the Pinus-Viscum-system to assess interdependencies among factors driving community structure.

到目前为止，几乎所有被研究的植物都生活在一个复杂的内生真菌组合中。然而，人们对这些社区构成的驱动因素知之甚少。在之前的一个项目中，我们首次获得证据表明，叶和茎中的内生真菌在多样性、可变性和寄主选择性方面存在差异。这项研究得出了几个假设。将在拟议的项目中检验的这些假设是：(A)茎栖真菌群落的物种相当少，(B)对其寄主植物物种具有一定的选择性，以及(C)在成年寄主植物中不随时间变化。相反，(D)叶片内的多样性被认为随着叶龄的增加而增加，(E)积累的真菌的光谱不是寄主选择性的。它的组成更多地取决于周围环境中是否有适合真菌产孢子的底物(即腐烂的植物材料)，因此取决于植物群落的组成。为了验证这些假设，选择了以前研究过的Pinus-Viscum系统，因为i)两种植物器官的年龄很容易确定，ii)两种植物至少包括当年和前一年的叶片，以及iii)由于它们非常接近，它们暴露在相同的真菌孢子谱中。焦磷酸测序将被应用于不同树龄的松属系统和未受感染的松树的不同树龄的茎和叶的五个重复中的每一个中的真菌DNA。通过这种方式收集的大量数据将允许在统计上合理的背景下解决这些假设。拟议方法的适用性先前已得到验证，焦化测序运行的成功得到外部承包商的保证。

Nearly all plants studied so far are inhabited by a complex assemblage of endophytic fungi. However, the factors driving the composition of these communities are poorly understood. In a previous project we obtained first evidence that the endophytic fungi in leaves and stems differ with regard to diversity, variability, and host-selectivity. Several hypotheses resulted from that study. These hypotheses to be tested in the proposed project are that (a) the stem-inhabiting fungal community is rather poor in species, (b) to a certain degree selective for their host plant species, and (c) does not change through time in adult host plants. In contrast, (d) the diversity within leaves is assumed to increase with increasing leaf age and (e) the spectrum of accumulating fungi is not host-selective. Its composition rather depends on the availability of suitable substrates for fungal sporulation (i.e. decaying plant material) in the surrounding environment and therefore on the composition of the plant community. To verify these hypotheses the previously studied Pinus-Viscum-system is chosen because i) the age of the organs of both plants is easily determinable, ii) both species comprise at least current- and previous-year leaves, and iii) they are exposed to the same spectrum of fungal spores, due to their close proximity. Pyrosequencing will be applied to fungal DNA in each of five replicates of differently aged stems and leaves of each species of the Pinus-Viscum-system and non-infected Pinus trees in addition. The extensive data gathered this way will allow addressing the hypotheses on a statistically sound background. The applicability of the proposed methodology has previously been verified and success of the pyrosequencing run is guaranteed by an external contractor.