Isolation of endophytic fungi and their mycorrhizal potential for the tropical epiphytic orchids cattleya skinneri, C. aurantiaca and Brassavola nodosa

In the present study, we screened endophytic fungi in roots of mature plants of the epiphytic orchid Cattleya skinneri to test their potential to improve seed germination in C. skinneri and growth and development in acclimatizing plantlets of C. aurantiaca and Brassavola nodosa. We isolated 108 fungal colonies belonging to 11 genera and statistical differences were not found between samples according to season or orchid substrate. Germination experiments were carried out using three methods and eight strains that proved to be manageable under laboratory conditions. None of these strains proved to be promoters of seed germination in C. skinneri. For ex vitro plants of C. aurantiaca, three strains (Trichoderma IBTZ-0200F, Epulorhiza IBTS-0200G and Botrytis IBTZ-0200A) showed mycorrhizal characteristics, whereas none of the evaluated strains promoted plant growth in B. nodosa. Fungal strain specificity and their function as mutualists, neutral or latent pathogens are discussed in the light of the results obtained.