Fungal diversity and ex vitro symbiotic germination of Serapias vomeracea (Orchidaceae)

Abstract

Conservation of orchids can be possible with effective seed germination and seedling growth methods. In this context, ex vitro symbiotic seed germination and seedling growth of orchid seeds may be convenient and advantageous. In this study, both the diversity of the root endophytic fungi in Serapias vomeracea (Burm.f.) Briq. and the ex vitro effects of these fungi on seed germination, seedling development and tuber formation were revealed. The fungi were isolated monthly for two years from S. vomeracea roots and the isolates were identified based on morphological characters and internal transcribed spacer (ITS) region of nuclear ribosomal DNA (rDNA) sequences. All of the Rhizoctonia-like isolates that joined the mycorrhizal association were closely related to Tulasnella calospora (thirty isolates). Non-Rhizoctonia isolates are closely related to Fusarium tricinctum (two isolates), Aspergillus spelaeus (one isolate) and Talaromyces pinophilus (Pezizales) (one isolate). The viability rate of the seeds was 90.32%. The seed packs were placed in soils containing fungus and the germination process was followed. All isolates associated with Tulasnella calospora promoted germination and seedling development. Isolate Svl 21 (Tulasnella sp.) was found to have the highest germination rate (98%) but isolate Svl 4 developed seedlings with advanced leaves (stage 4 (S4): seedlings with advanced leaves and/or rooted, 13.67%). All seedlings at S4 were transferred to the natural environment; the first tubers were observed seven months after. In this study, for the first time, a tuberous European orchid, S. vomeracea developed from seed to adult plant in a natural environment.