Revisiting endophytic fungi of the Pinus-Viscum-system to assess interdependencies among factors driving community structure.
Final Report Abstract
The project aimed to reveal the impact of host plant species, organ type, organ age and geographical location on the composition of endophytic fungal communities. Therefore, 170 samples from 1 to 3 year old leaves and stems of Pinus sylvestris and Viscum album were collected at 2 locations and surface sterilized. Fungal ITS1 regions of the rRNA gene were amplified and sequenced using ‘454-pyrosequencing’. The analysis revealed altogether 154 fungal OTUs (represented by 953,385 sequences) occurring in at least 2 samples. Deviating from earlier assessments, representatives of Mortierella (Zygomycota) were most abundant. Composition of the fungal communities differed predominantly between host plants and organs. Interestingly, these differences were predominantly caused by host preferences fungi known to be involved in plant litter decomposition. While differences were significant but weakly pronounced between locations and sampling dates, age of the organs had no significant effect. Accordingly the study revealed 3 major new insights: First, certain species of Mortierella may colonize aboveground plant tissues internally. Second, decomposer fungi prefer certain plants and/or organs during an endophytic life stage. Third, compositional shifts of endophytic fungal communities are more pronounced within than between years. In particular the realization that endophytic and plant litter decomposing fungal communities are closely connected is of major importance for future studies focusing on the ecology of plant associated fungi: Fungal host/organ preferences in the endophytic stage may have an impact on litter decomposition processes, while litter quality and soil properties may affect the structure of endophytic fungal communities in return. Accordingly, knowledge of the complete life cycle of endophytic and decomposer fungi is required to assess their functional roles in ecosystem processes. Therefore, simultaneous studies of fungal communities in phyllosphere and pedosphere will certainly maximize the knowledge gained in related future projects.
