Mycorrhizal fungi associated with Codonorchis lessonii (Brongn.) Lindl., a terrestrial orchid from Chile

Abstract

Almost all orchid species depend on association with fungal partners. These fungal species facilitate orchid seed germination
and promote growth and possibly stress tolerance in adult plants, both in the field and laboratory conditions. Codonorchis
lessonii is a terrestrial orchid, endemic to southern Chile and Argentina with a currently unknown conservation status.
Previous studies have reported Rhizoctonia-like fungi associated with C. lessonii in Argentina, but their fungal partners
in Chilean populations are unknown. This study aims to characterize and isolate the mycorrhizal fungi associated with
adult individuals of C. lessonii from three different populations in Central-South Chile. Root sections showing pelotons
were used for the isolation and identification of the fungal taxa. Radial fungal growth was measured for all mycelial
isolates. The presence of binucleate cells placed all isolates within the families Ceratobasidiaceae and Tulasnellaceae
and the identification was confirmed by molecular analysis. Fungal isolates belonging to Ceratobasidiaceae grew at a
higher rate than those from Tulasnellaceae. Phylogenetic analyses showed that different fungal partners associate with this
orchid, suggesting relatively low specificity. The isolation and identification of the fungal partners of C. lessonii could help
understand its ecology and contribute in future restoration and propagation initiatives for the species.