The micorryzal fungi Ceratobasidium sp. and Sebacina vermifera promote seed germination and seedling development of the terrestrial orchid Epidendrum secundum Jacq

The interaction between seeds and mycorrhizal fungi in germination and developmental processes is complex and far from being understood. The efficiency assessment of mycorrhizal fungi at in vitro seed germination of orchids will improve protocols for conservation and horticultural purposes. Applying a culture-dependent approach, we isolated 45 endophytic fungi, from roots of 12 orchid species, growing at two altitudinal levels in the Ecuadorian mountains. From them, 26 Rhizoctonia-like axenical isolates were studied by nuclear ribosomal rDNA sequences analysis, searching for mycorrhizal fungi. Ceratobasidium sp. and Sebacina vermifera were identified and tested for promoting germination and seedling development of Epidendrum secundum Jacq., an endangered medicinal orchid. Symbiotic cultures were stablished in Oat Meal Agar (OMA), and seeds development was compared between Murashige & Skoog enriched medium (MS) and OMA. Germination and seedling development was evaluated during 60 days. Compared with MS medium, symbiotic cultures enhanced plantlets development and significantly reduced germination time. 47.3% and 8.8% of the seeds growing symbiotically with Ceratobasidium sp. and S. vermifera, respectively, reached plantlets stage. The average height from the plantlets growth in symbiotic treatments were higher than MS and OMA treatments (p < .05). E. secundum symbiotically cultured with Ceratobasidium sp. grew higher compared to S. vermifera co-culture. The isolation of two fungi promoting seed germination and development of E. secundum will allow the improvement of in vitro reproduction of this valuable orchid and might be tested in other endangered species for conservation and reproduction purposes. (C) 2019 SAAB. Published by Elsevier B.V. All rights reserved.