Integrating stable isotope and fungal association evidence for nutrient acquisition in the rare orchid, Risleya atropurpurea

Titelangaben

Jiang, Hong ; Liao, Wen Yu ; Qin, Liping ; Lee, Yung-I ; Gebauer, Gerhard:
Integrating stable isotope and fungal association evidence for nutrient acquisition in the rare orchid, Risleya atropurpurea.
In: Mycorrhiza. Bd. 36 (2026) . - 64.
ISSN 1432-1890
DOI: https://doi.org/10.1007/s00572-026-01311-1

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Abstract

Risleya atropurpurea, a fully mycoheterotrophic species in the subtribe Calypsoinae, is a rare Himalayan orchid whose
fungal associations and nutritional strategy remain poorly understood. In this study, we combined high-throughput ITS
amplicon sequencing and stable isotope natural abundance analyses to investigate the mycorrhizal associations and nutrient acquisition strategy of R. atropurpurea in a natural habitat in southwestern China. Fungal community profiling revealed the dominance of a single operational taxonomic unit affiliated with Basidiodendron caesiocinereum (Auriculariales). Stable isotope analyses showed that R. atropurpurea was significantly enriched in both ¹³C and ¹⁵N relative to neighboring autotrophic reference plants, consistent with isotope patterns characteristic of fully mycoheterotrophic orchids associated with saprotrophic wood-decaying fungi. Together, these findings indicate that Basidiodendron is likely to contribute to carbon and nitrogen acquisition in R. atropurpurea and suggest that Auriculariales-associated saprotrophic fungi may represent an under-recognized nutritional partner in fully mycoheterotrophic orchids. Our study expands the known diversity of fungal partners involved in orchid mycoheterotrophy and provides new insights into the ecological evolution of fungal-dependent nutrition in orchids.