Abstract

In this study, the diversity of leaf-associated microorganisms of the native Andean ericaceous plants Gaultheria pumila and Empetrum rubrum was screened to identify and characterize microorganisms with plant growth promotion and biocontrol capability against the phytopathogenic fungus Botrytis cinerea affecting Vaccinium corymbosum cultivars. Microbial strains with biocontrol potential against Botrytis cinerea were selected, and in vivo tests were performed to evaluate the biocontrol activity of the selected strains. The fungi Epicoccum nigrum (strains HFE11 and HFG20), Epicoccum layuense (strain HFG13), and Aspergillus sp. (strain HFG1), the yeasts Aureobasidium pullulans (strains BFG22 and BFG24) Sporobolomyces roseus (strains BFE10 and BFE11), and the bacteria Bacillus mycoides (strains BFE4 and BFE14), Bacillus sp. (strain BFG8), Pseudomonas fluorescens (strain BFE6), and Pseudomonas sp. (strain BFG21) were isolated. In vitro biocontrol activity of the selected strains (BFE14, BFE6, and HFG13) showed inhibition percentages ranging from 60 to 80%. Most of the isolates were able to produce Exopolysaccharides, Siderophore, Indole-3-acetic acid, P-solubilization and Ammonia to different levels. The in vivo experiments showed that the inoculation of the isolates BFG22, BFE6, and HFG13 on V. corymbosum leaves before infection avoids severe damage to the infected tissues. Additionally, BFG22 decreases the lipid peroxidation levels (malondialdehyde 36% lower) when the leaves were infected with B. cinerea. Our results provide evidence of beneficial traits of microorganisms inhabiting the phyllosphere of native Ericaceae which can be used as microbial inoculants in agricultural production. These beneficial effects enhance plant growth and avoid damage by B. cinerea in V. corymbosum cultivars.