Whereas the EcoSim analysis suggests an overall signature of negative co-occurrence, Fisher’s Exact test indicates negative and positive co-occurrences for certain species pairings. It is noteworthy that none of the three additional species exhibited negative co-occurrence with M. bolleyi and M. phragmitis in the total data set. Instead, M. bolleyi generally co-occurred significantly more frequently with Ms7Mb4 and Ms43Mb21 than expected
by chance. Such a positive co-occurrence may appear when the conditions that are conducive for one species are also favorable for another species. Alternatively, positive co-occurrence may result MLN8237 in vivo from synergism. On the other hand, there existed an overall negative co-occurrence between Stagonospora sp. and Ms7Mb4, significantly preferring leaves  and roots , respectively. This could
have resulted from strongly contrasting niche OICR-9429 molecular weight preferences, severe competition for the same substrates or from the secretion of toxins (antagonism). Our results suggest that it is rather unlikely that antagonism by any of the other three fungi is responsible for the differential colonization of roots by Microdochium spp. Since the fungal community on common reed is larger than addressed here, we cannot rule out that other endophytes may SIS3 exert such influences. Conclusions This study supports the concept that niche partitioning allows for differential colonization of common reed by the fungal species investigated. Therefore, Montelukast Sodium a purely neutral model is unlikely to explain the assembly of the mycoflora of common reed. Nonetheless, it remains to be shown to what extent stochastic factors could also contribute to variations in the composition, distribution and diversity of this fungal community. Acknowledgements This work was financially supported by the Deutsche Forschungsgemeinschaft through SFB 454 (Bodenseelitoral). We thank Dr. Jan Nechwatal
(Universität Konstanz) for providing the temperature data for Lake Constance and for discussion of the data. We gratefully acknowledge Dr. Willi Nagl (Universität Konstanz) for advice on statistics, Dr. Ulrike Damm (CBS, Utrecht) for advice on taxonomy, and Michael Koch (Universität Konstanz) for technical help. Electronic supplementary material Additional file 1: Details of isolates studied. This file provides a list of 21 Microdochium isolates used in this study, including accession numbers of ITS sequences and information about their origins. (PDF 11 KB) Additional file 2: Specificity of nested-PCR assays targeting Microdochium spp. This file documents the specificity of the assays employed. A) First PCR step using primers ITS1F and ITS4. M = 100 bp size standard, water: no template DNA included, P. australis: genomic DNA of axenically grown reed plants, genomic DNAs from fungal isolates 4/97-9 (Humicola sp.), 6/97-38 (Chaetomium sp.), 6/97-54 (Fusarium sp.), A4 (Fusarium sp.), 5/97-16 (Microdochium phragmitis), 5/97-54 (M.