In this project we have explored the specificity of fungal interactions in a group of Australian orchids, Caladenia species, through experiments on germination and development using fungal cultures. We isolated orchid mycorrhizal fungi from ca. 50 orchid taxa from Western Australia. These fungi were cultivated and preserved for future conservation projects. By combining mycorrhizal fungi from axenic culture and surface-sterilized orchid seeds we inoculated various fungal strains at germination stage to understand their impact on germination and subsequent seedling growth.
By using the seeds of native non-orchid species and fungal strains of Serendipita isolated from WA orchids, we designed a transformative microcosm experiment aimed at illuminating the relationship between the plant community and orchids in facilitating mycorrhizal fungi movement. We inoculated neighbouring non-orchid plants with orchid mycorrhizal fungi, and we are looking for root colonization under the microscope to verify if Australian shrubs and trees can host orchid mycorrhizal fungi as endophytes and be a reservoir of these organisms during the hot and dry season.
By means of species distribution models, we predicted the distribution of 26 Caladenia species from WA under past and future climatic scenarios. Our results show that for most of the studied taxa, their range extent will not vary or may expand, including for some currently threatened species. This means that the current decreasing number of individuals and populations for some species is due to habitat disturbance, or other environmental/anthropic stressors not necessarily related to increasing temperatures. Indeed, in vitro experiments to test tolerance of orchid seeds and fungal to temperature are showing that both orchid seeds and fungi are resilient to changing climatic conditions.
Climate change and increased fire frequency are significantly impacting soil fungal communities worldwide, potentially disrupting essential ecosystem processes. We investigated fungal community composition across pristine and post-fire sites in WA where the critically endangered underground orchid occurs to understand how these disturbances affect soil microbiota and their recovery patterns. Analysis of soil samples from these sites revealed distinct fungal communities between burnt and unburnt areas.The pristine sites showed higher abundances of OMF, while post-fire sites exhibited increased presence of early-successional taxa. The results demonstrated that burnt sites are progressing toward a community structure more similar to unburnt areas, suggesting ongoing ecological recovery and resilience of fungal communities following fire disturbance.
We also focused on the critically endangered orchid Caladenia huegelii in WA by collecting soil samples from four sites over two years, including a site selected for translocation. Using fungal metabarcoding, we tracked temporal changes in OMF community and analyzed their relationship with continuous soil temperature and humidity data from in situ data loggers. The integration of fungal community dynamics and microclimate patterns enabled identification of the most suitable, climate-resilient sites for future seedling translocation. These findings provide a science-based framework for conservation, ensuring that translocation efforts support both the orchid and its essential fungal partners under changing environmental conditions.
In the European phase of the project, we focused on investigating the temperature and humidity tolerance of orchid seeds and mycorrhizal fungi isolated from European species. Also, we isolated fungi from British and Greek orchid species. We have performed a molecular experiment investigating the presence of orchid mycorrhizal fungi in different orchid tissues (rather than just roots) using both DNA and RNA as template for amplifications. This innovative approach will allow us not only to detect the presence of these fungi but also to investigate their activity and functions in the different orchid tissues.
