Browsing by Author "Pomavilla Lema, Yesenia Marisol"

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Endophytic fungi associated with roots of epiphytic orchids in two andean forests in southern Ecuador and their role in germination
(2020) Salazar Orellana, Marjorie Jazmin; Pomavilla Lema, Yesenia Marisol; Pollard, Anne Therese; Chica Martínez, Eduardo José; Peña Tapia, Denisse Fabiola
Orchids are known to establish complex relationships with endophytic fungi throughout their life cycle, and particularly during germination of their reserves-deprived seeds. Characterizing generalist or specialist interactions between orchids and associated fungi is key to supporting orchid conservation efforts. Here, endophytic fungi associated with roots of epiphytic orchids were studied in two montane Andean forests in Southern Ecuador. Orchid root samples were collected from ten ~500 m 2 plots distributed between two neighboring forests. Endophytic fungi associated with these roots were then isolated, cultured, and identified by sequencing of rDNA markers. In total, 52 pure isolates were recovered from the roots of 10 orchid species. These isolates were classified into nine taxonomic groups except for one isolate that remained unclassified. Most fungal isolates were found in roots of up to two different orchid species; however, Coprinellus radians was found in the roots of all sampled orchids. The potential of C. radians to promote germination of orchid seeds was tested in a separate assay using seeds from two orchid species different than those found in the experimental forest plots. Of the two C. radians isolates tested, one improved germination in the two orchids evaluated to a level about half of that observed in seeds germinated in nutrient-rich medium (Phytamax) and above the null germination observed in plates without the fungus. Together, these results revealed a generalist relationship between C. radians and all the studied epiphytic orchids and the potential role of this fungus as a promoter of orchid seed germination
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
(2018) Pomavilla Lema, Yesenia Marisol; Peña Tapia, Denisse Fabiola
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