Plant growth promoting endophytic fungi from three species of tropical epiphytes from Chiapas, Mexico

Background: Various epiphytic plants grow grouped together or separately on the phorophytes, harboring a diversity of endophytic fungi, and some possess characteristics that promote plant growth. Questions: ¿What cultivable endophytic fungal species with plant growth-promoting properties are present in epiphytes growing in groups and individually? Studied species: Brassia verrucosa, Tillandsia guatemalensis and one species of Dicranaceae. Study site and dates: Ejido Benito Juárez, El Plan, Municipality of Cacahoatán, Chiapas, Mexico; 2021-2022. Methods: Plants of the three species (groups and individually) were collected for the isolation of endophytic fungi. Their inorganic phosphate solubilization capacity, indole-3-acetic acid production and pH (with/without L-tryptophan), and tannic acid degradation were evaluated. Morphological and molecular identification of the selected fungi was performed (only B. verrucosa ITS-EF1α). Results: Twenty-eight endophytic fungi from the three plants were selected based on their solubilization capacity, indole-3-acetic acid production, and tannic acid degradation. Of these, seven fungi were frequently isolated from both grouped and individual plants. Aspergillus versicolor stood out in solubilization, while Fusarium sp. excelled in the production of indole-3-acetic acid (with/without L-tryptophan). The fungi with the highest indole-3-acetic acid production showed pH values of 4,0 with L-tryptophan and 4,5 without L-tryptophan. Most of the selected fungi exhibited tannic acid degradation. Conclusions: Aspergillus foetidus, Colletotrichum chrysophilum, Colletotrichum kahawae, R3-T-P1-H-C19, and Fusarium sp. could be used as inoculum for the propagation and in vitro development of epiphytic plants.