The genus Tulasnella in orchid mycorrhizal symbiosis: diversity, functional biology, and emerging perspectives
Rhizosphere, vol.39, 2026 (SCI-Expanded, Scopus)
- Publication Type: Article / Review
- Volume: 39
- Publication Date: 2026
- Doi Number: 10.1016/j.rhisph.2026.101410
- Journal Name: Rhizosphere
- Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
- Keywords: Host specificity, Orchid conservation, Peloton, Symbiotic germination, Tulasnella
- Ondokuz Mayıs University Affiliated: No
Abstract
The genus Tulasnella (Tulasnellaceae, Basidiomycota) comprises one of the most widespread and ecologically important groups of orchid mycorrhizal fungi. These fungi are central to orchid biology, particularly during seed germination and early development, when they provide essential carbon and nutrients to nutrient-poor embryos. Despite growing research interest, current knowledge of Tulasnella remains fragmented across taxonomic, ecological, and functional studies. In this review, I synthesize recent advances in the taxonomy, phylogeny, diversity, and symbiotic biology of Tulasnella associated with orchids. Molecular phylogenetic studies have revealed extensive cryptic diversity within the genus, challenging traditional morphology-based classification and emphasizing the need for integrative taxonomic approaches. Ecological investigations further indicate that Tulasnella exhibits broad geographic distribution and variable host specificity, ranging from generalist associations to highly specialized interactions that can influence orchid distribution and population dynamics. Recent omics-based studies have substantially improved our understanding of the molecular and metabolic processes underlying Tulasnella–orchid symbiosis. These include early signalling before physical contact, dynamic intracellular colonization via peloton formation, and nutrient exchange via carbon- and nitrogen-related pathways. However, important questions remain unresolved, particularly regarding the molecular determinants of host specificity, the regulation of nutrient flux, and the extent of functional variation among lineages and strains. By integrating findings across multiple disciplines, this review highlights the ecological and evolutionary significance of Tulasnella and identifies key knowledge gaps that should guide future research. Advancing our understanding of Tulasnella biology will not only deepen insight into orchid–fungus interactions but also support orchid conservation and symbiotic propagation strategies.