Exploring the biocontrol potential of fungal endophytes from an Andean Colombian Paramo ecosystem

Abstract

We studied the diversity and biocontrol potential of 100 fungal endophytes isolated from Espeletia spp., endemic plant species from the Paramo in the Andean mountain range. Our sample was genotypically highly diverse at all ITS similarity levels. The antagonistic properties of these isolates were tested against common crop pathogens in Colombia, including Pectobacterium carotovorum, Ralstonia solanacearum, Pseudomonas syringae, Xanthomonas campestris, Rhizoctonia solani, Botrytis cinerea, Fusarium oxysporum, and Phytophthora infestans. All endophytic isolates were able to significantly inhibit the growth of at least one of the plant pathogens tested (P \ 0.05). Three main types of endophyte/pathogen interactions were observed.However, only those endophytes that produced an evident inhibition halo were further studied using their crude extracts to confirm that the inhibitory effect was due to the production of endophytic bioactive metabolites. From these experiments, nine promising isolates were selected for co-inoculation tests with R. solani in tomato plants. The isolates identified as Aureobasidium pullulans and Paraconiothyrium sporulosum not only protected the plants against this pathogen but also allowed them to exhibit similar growth and development as the uninoculated control. This work explores new alternatives for disease management without the application of chemical pesticides.

Microbial and Functional Diversity within the Phyllosphere of Espeletia Species in an Andean High-Mountain Ecosystem

“…Endophyte DNA was isolated according to previously reported methodologies, with some modifications (12,19). Briefly, the plant tissue was surface sterilized by washing with sterile H 2 O to remove dirt, placed in NAP buffer (124 mM Na 2 HPO 4 ), and vortexed for 1 min to dislodge epiphytes.…”

“…Briefly, the plant tissue was surface sterilized by washing with sterile H 2 O to remove dirt, placed in NAP buffer (124 mM Na 2 HPO 4 ), and vortexed for 1 min to dislodge epiphytes. Leaves were then shaved to remove the pubescence on their surface, which facilitates the subsequent sterilization process (12), washed with sterile H 2 O, submerged in 90% ethanol (60 s), 5.25% sodium hypochlorite solution (6 min), and 70% ethanol (30 s), and finally rinsed with sterile distilled H 2 O. Sterilization was checked by taking an imprint of the leaf on malt extract medium (12) and incubating at 25°C. One gram of the previously treated material was cut into 0.1-to 0.5-mm sections, placed in a 1.5-ml Eppendorf tube containing 1 g of sterile 0.1-mm-diameter glass beads and 1 ml TE (10 mM Tris, 10 mM EDTA, pH 8.0), and homogenized in a Mini-BeadBeater (BioSpec Products) for 5 min.…”

“…These plants have unique adaptations that enable them to resist exposure to UV light and daily temperature changes; they are in close relation with more than 125 animal species (10) and are important for soil health and the capacity of these ecosystems to retain and regulate water availability and to store carbon (11). Based on the developmental stage, these plants can be separated into different "tiers" (12). The upper tier is composed of young leaves somewhat protected from the environment, the middle tier (midtier) is composed of fully mature leaves exposed to environmental conditions, and the necromass tier is composed of senescent leaves (Fig.…”

“…Some studies done by culturing bacteria and fungi, including mycorrhizae, indicate that many microorganisms are commonly associated with these plants and are probably important for nutrient availability and decomposition of biomass (14)(15)(16). Other work has focused on endophytic fungi and their biocontrol and biotechno-logical potential (12,17). In this work, we used culture-independent means, 16S rRNA gene sequencing and GeoChip 5.0 functional microarrays, to address community structure, diversity, and functional potential using samples from different plant tiers.…”

Entomopathogen Metarhizium anisopliae promotes the early development of peanut root

“…Trichoderma harzianum strain T22, known to control plant-pathogenic fungus, could make maize roots deeper and more robust with a greater surface area compared with the untreated control (Harman et al 2004). aureobasidium pullulans and Paraconiothyrium sporulosum were not only antagonistic to the tomato pathogen R. solani, but also exhibited tomato growth promotion (Miles et al 2012). Piriformospora indica was found in endophytically colonized roots and could promote the root growth of a number of plant species, including maize, tobacco, and parsley (Varma et al 1999).…”