This genome was sequenced as part of the 1000 Fungal Genomes Project - Deep Sequencing of Ecologically-relevant Dikarya. Within the framework of this project, we are sequencing keystone lineages of saprophytic, mycorrhizal, and endophytic fungi that are of special ecological importance. Dozens of sequenced species were harvested from Long Term Observatories to serve as the foundation for a reference database for metagenomics of fungi and for a comprehensive survey of the soil fungal metatranscriptome.
Tulasnella spp.
Tulasnella is a genus of fungi in the family Tulasnellaceae. Tulasnella spp. are considered the most important mycobionts of Orchidaceae (Cruz et al., 2014). Fungi in the genus Tulasnella have been isolated from orchids in Asia, Australia, Europe, South America (Freitas et al., 2020), and North America. Despite the importance of Tulasnella as mycorrhizal partners, many species remain undescribed, and little is known about their ecology, beyond their associations with orchids. Many orchids have an obligatory relationship with Tulasnella mycorrhizal fungi for seed germination and support into and throughout adulthood. Mycorrhizal fungi are a fundamental component of nearly all terrestrial ecosystems, creating the critical link between above- and below-ground systems by establishing an intimate association with the roots of >90% of land plants. This relationship provides plant partners with improved nutrient acquisition from the soil, stress tolerance, and pathogen protection. Most mycorrhizal associations also allow the fungal partners to obtain the photosynthetically fixed carbon sources they need to survive and reproduce.
Figure1 is from a fungal culture grown from pelotons isolated from roots of an adult Platanthera blephariglottis. Isolated pelotons were grown on E-medium (Caldwell et al., 2000) at 25 °C for 1–4 weeks. Observations, measurements, and photographic images of microscopicfungal structures were recorded using a Hirox Digital microscope. Species within the genus Tulasnella may be further differentiated based on their morphological features, such as the shape and size of their spores (although spores are rarely produced in culture), the structure of their mycelium, and other microscopic characteristics. Molecular techniques, including DNA sequencing, are increasingly being used to refine and confirm the classification of fungal taxa. Understanding the specific mycorrhizal relationships between fungi like Tulasnella and orchids is crucial for the successful cultivation and conservation of orchid species, as these relationships play a significant role in the orchids' life cycle and growth. Figure 2 is of a blooming host plant: Platanthera blephariglottis. Photo credits: Eranga Wettewa.
Researchers who wish to publish analyses using data from unpublished CSP genomes are respectfully required to contact the PI and JGI to avoid potential conflicts on data use and coordinate other publications with the CSP master paper(s).
Acknowledgement: Melissa McCormick, Principal Investigator, Molecular Ecology Lab, Smithsonian Environmental Research Center.
References:
1. Cruz, D., Suárez, J. P., Kottke, I., & Piepenbring, M. (2014). Cryptic species revealed bymolecular phylogenetic analysis of sequences obtained from basidiomata of Tulasnella. Mycologia, 106(4), 708-722.
2. Caldwell, B. A., Jumpponen, A., & Trappe, J. M. (2000). Utilization of major detritalsubstrates by dark-septate, root endophytes. Mycologia, 230-232.
3. Freitas, E. F. S., da Silva, M., Cruz, E. D. S., Mangaravite, E., Bocayuva, M. F., Veloso, T. G. R., Selosse, M., & Kasuya, M. C. M. (2020). Diversity of mycorrhizal Tulasnella associated with epiphytic and rupicolous orchids from the Brazilian Atlantic Forest, including four new species. Scientific Reports, 10(1), 7069.
