Evaluación de la actividad promotora de la germinación de cuatro cepas de hongos endófitos de raíces de Epidendrum sp. en la germinación de dos especies del mismo género

Abstract

Most orchids depend on association with mycorrhizal fungi to germinate and develop. As a consequence, endophytic fungi from which orchids can obtain nutriente are of key importance to allow orchid seeds to germinate in their natural habitats and sustain viable populations. With almost 4000 species reported, Ecuador is a country that harbors one of the greatest diversity of orchids in the world. Unfortunately, many of these species are threatened by illegal extraction for commerce and the reduction of their natural habitats. These threats have already put many of these orchids in a threatened or at risk conservation status. Considering these threats and the natural difficulties to germinate orchid seeds, the development of improved germination protocols for these species could contribute to their conservation in nature and to develop potential sustainable use models. The objective of this project was to evaluate four endophytic fungi for their potential effect on germination of Epidendrum spp. Of the four fungi evaluated, only one showed a germination-enhancing effect (Coprinellus sp2.) and caused seeds to develop up to stage 3 (rizoid emergence) whereas seeds germinated in the presence of other fungi (Trametes sp., Coprinellus sp1. and a mycorrizhal Basidiomycete) only reached germination stage 1 (complete imbibition). None of the fungi induced germination to the levels observed in the positive germination control (Phytamax). Since only Coprinellus sp2. induced increased germination in relation with other fungi and the negative control (oatmeal agar), this fungi was further characterized morphologically. The results suggest that Coprinellus sp2 could be a generalist endophytic fungus since the effect was observed in both Epidendrum spp. evaluated which were different from the species from which the fungus was isolated. This generalist effect could even expand to other orchids outside Epidendrum since Coprinellus spp. have been isolated from roots of different orchid genera from Andean forest in southern Ecuador