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Fungal root endophytes of Quercus robur subjected to flooding

Kwaśna, H., Szewczyk, W., Behnke‐Borowczyk, J., Woodward, S.
Forest pathology 2016 v.46 no.1 pp. 35-46
Aspergillus, Basidiomycota, Chaetomium globosum, Cosmospora, Pezicula, Pyrenochaeta, Quercus robur, Sporothrix, Trichoderma harzianum, Zygomycota, decline, endophytes, fine roots, floods, forests, fungi, internal transcribed spacers, ribosomal DNA, species diversity, trees
In August 2011, fungal endophytes were isolated from fine (0.1–0.5 cm diameter) and structural (0.6–2.0 cm) roots from eighteen Q. robur trees at six sites in a Q. robur‐dominated forest displaying symptoms of oak decline. Five sites were subjected to periodic flooding for 3 months in 1997 and 1 month in 2010. Fungal colonization was detected in 94% of 1296 root fragments examined. Fungi representing 126 taxa from Zygomycota (four species), Ascomycota (117 species) and Basidiomycota (five species) were isolated using culture‐based methods and identified by morphotyping and sequencing of the ITS 1 and 2 rDNA. The most frequent eudominants (with colonization frequencies ≥10%) were Aspergillus spp., Cosmospora sp., Ilyonectria radicicola, Pezicula radicicola, Pyrenochaeta cava and six species of Trichoderma. Species composition did not vary greatly between sites, but only 3% of species occurred in all sites. Number of species was higher in roots subjected to floods. Eudominants and dominants present only on flooded sites included Aspergillus spp., Chaetomium globosum, Cosmospora sp., I. radicicola, Sporothrix inflata, Trichoderma harzianum, T. pubescens and T. virens. Structural roots were usually colonized by a higher number of species than fine roots. The majority of species detected belong to Class 2 NC‐endophytes. Pezicula radicicola and Phialocephala fortinii belong to Class 4 NC‐endophytes.