The Microbiome of the ‘Williams’ Pear Variety Grown in the Organic Orchard and Antifungal Activity by the Autochthonous Bacterial and Yeast Isolates

Abstract

The total diversity of bacterial and fungal communities associated with the phyllosphere (fruits and leaves) of the 'Williams' pear variety was analyzed in two phenological stages during fruit development and maturation. The antagonistic potential of autochthonous bacterial and yeast isolates against phytopathogenic fungi was also evaluated. A metabarcoding approach revealed <i>Pantoea</i>, <i>Sphingomonas</i>, <i>Hymenobacter</i>, <i>Massilia</i>, and <i>Pseudomonas</i> as dominant bacterial constituents of the pear phyllosphere, whilst most abundant among the fungal representatives identified were <i>Metschnikowia</i>, <i>Filobasidium</i>, <i>Aureobasidium</i><i>pullulans</i>, <i>Botrytis cinerea</i>, and <i>Taphrina</i>. The traditional culturable approach revealed that the <i>Pseudomonas</i> genus with <i>P. graminis</i>, <i>P. putida</i>, and <i>P. congelans</i> was most prevalent. The most frequently cultivated fungal representatives belonged to the genus <i>Fusarium</i> with six identified species. A broad range of the antagonistic activity was detected for the <i>Hannaella luteola</i> and <i>Metschnikowia pulcherrima</i> yeasts, significantly affecting the growth of many fungal isolates in the range of 53-70%. <i>Fusarium sporotrichioides</i> was the most susceptible fungal isolate. The autochthonous antagonistic yeasts <i>H. luteola</i> and <i>M. pulcherrima</i> might be powerful biological control agents of postharvest diseases caused by <i>Fusarium</i> spp. and common pathogens like <i>Monilinia laxa</i>, <i>Botrytis cinerea</i>, <i>Alternaria tenuissima</i>, and <i>Cladosporium cladosporioides</i>.