Diversity of the Capnocheirides rhododendri-dominated fungal community in the phyllosphere of Rhododendron ferrugineum L.
Flessa, Fabienne; Rambold, Gerhard
Individuals of Rhododendron ferrugineum at natural sites within the mountain ranges and valleys Flüela, Julier, Monstein and Grimsel (in the cantons of Graubünden and Bern, Switzerland) were analysed to determine the occurrence of pigmented epifoliar fungi in their phyllosphere. Molecular data from the fungal isolates revealed a wide range of species to be present, forming a well characterized oligospecific community, with Capnocheirides rhododendri (Mycosphaerellaceae, Capnodiales, Ascomycota) being the most frequently occurring taxon. One group of fungi was exclusively isolated from the leaf surfaces and recognized as being residential epifoliar. A second ecological group was absolutely restricted to the inner leaf tissues and considered as truly endofoliar. Members of a third group occurring in both the epifoliar and endofoliar habitats were considered to have an intermediate life habit. Members of this latter group are likely to invade the inner leaf tissues from the outside after having established a mycelium on the leaf surface. Comparison of the degree of pigmentation between cultivated strains of the strictly epifoliar and strictly endofoliar community members provided some indication that epifoliar growth is to a certain degree correlated with the ability of the fungi to develop hyphal pigmentation. The endofoliar growth is assumed to entail a complete lack or presence of a more or less weak hyphal pigmentation.