Occurrence of non-obligate microfungi inside lichen thalli

Five corticolous lichen species (four foliose and one fruticose) and the leaf and bark tissues of their host trees were screened for the presence of asymptomatic, culturable microfungi. Four isolation procedures were evaluated to identify the most suitable one for isolating the internal mycobiota of lichens. A total of 242 isolates of 21 fungal genera were recovered from 500 thallus segments of the lichens. Different fungi dominated the fungal assemblages of the lichen thalli and the host tissues. An ordination analysis showed that there was little overlap between the fungi of the lichens and those of the host tissues even though, considering their close proximity, they must have been exposed to the same fungal inoculum. This is the first study that compares the microfungal assemblage associated with lichens with those occurring in their substrates. It indicates that lichen thalli, apart from their obligate mycobiont, could serve as an ecological niche for certain microfungi.