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

Durán-López, M.E., Caroca-Cáceres, R., Jahreis, K., Narváez-Vera, M., Ansaloni, R., Cazar, M.E.
South African journal of botany 2019 v.125 pp. 54-61
Ceratobasidium, Epidendrum, Sebacina vermifera, agar, altitude, coculture, endangered species, endophytes, horticulture, mountains, mycorrhizal fungi, nucleotide sequences, oatmeal, plantlets, reproduction, ribosomal DNA, roots, seed germination, seedlings, seeds
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.