Diversity of orchid root-associated fungi in montane forest of Southern Ecuador and impact of environmental factors on community composition
(2018)
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- Abstract
- Orchidaceae is one of the largest families of vascular plants, distributed in almost all terrestrial ecosystems. Their roots are associated with fungi, which are necessary for completing their life cycle. Orchids-fungi associations are thus considered unique model systems for studying biotic interactions and co-evolutionary dynamics. The root-associated fungi (RAF) most often reported with orchids belong to Basidiomycota and Ascomycota phylum. They are believed to influence orchid spatial distribution and population dynamics. Interaction studies between orchids and fungi have mainly been focused on taxonomic identification of the endophytic RAF, while the environmental (abiotic and biotic) factors affecting these interactions were less considered. There is thus a need for studies focusing on the impact of ecosystem changes on RAF communities and species dynamics. With the recent development of high-throughput sequencing technologies (e.g. the next generation sequencing (NGS)), more in-deep ecological insights are possible. In the present thesis, we used molecular approaches (i.e. Illumina MiSeq technology) and field experiments to acquire new knowledge on the dynamics of orchids and fungi in tropical ecosystems. We aimed to evaluate the (1) diversity of endophytic RAF (mycorrhizal and non-mycorrhizal fungi) of epiphytic orchids and (2) abiotic and biotic factors affecting the orchid-fungi interaction. The study was conducted in two areas of montane rainforest in Southern Ecuador (Podocarpus National Park and Cajas National Park). Our results demonstrated that epiphytic orchids in the Podocarpus National Park had different endophytic RAF community compositions that depend on abiotic and biotic factors such as host phylogeny, site, altitudinal levels and temporal variation. Contrastingly, endophytic RAF of orchids at Cajas National Park seemed to harbor more homogenous communities. The endophytic RAF identified included mycorrhizal and non-mycorrhizal fungi that were putatively classified as symbionts, saprophytes or pathogens. The potential benefits of the non-mycorrhizal fungi on orchid’s life remains unresolved. However, it is hypothesized that the interaction with multiple fungi could favor orchid site occurrence and co-existence among several orchid species. Additionally, our results suggested that orchid populations have site-adjusted fungal endophytic communities, structured around keystone fungal species (widely distributed) and fungal species locally available. The combined use of field and laboratory approaches undoubtedly contributed to the understanding of the interactions that occurred between orchids and fungi, generating stronger ecological premises for species conservation.
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Citations
Cevallos Solorzano, S. (2018). Diversity of orchid root-associated fungi in montane forest of Southern Ecuador and impact of environmental factors on community composition. https://hdl.handle.net/2078.5/125467