Unveiling microbial community dynamics in response to pear brown spot disease and management strategies

Pear brown spot, caused by the Ascomycete fungus Stemphy¬lium vesicarium, is a major economic threat to pear produc¬tion in northern Italy. This study investigated the influence of microbial communities on brown spot development and the impact of disease management strategies on these com¬munities. The specific objectives of the project are: A) To compare microbial communities (bacteria and fungi) on pear surfaces (cv. Abate Fétel) in orchards conducted with organic and integrated pest management; B) To investigate potential correlations between S. vesicarium and the adopted disease control strategy, S. vesicarium abundance and brown spot incidence, specific microbial taxa and S. vesicarium abun¬dance. Metabarcoding with high-throughput sequencing was employed to analyse the epiphytic microbial communities on pear surfaces from both orchard types. We targeted the V3-V4 region of the 16S rRNA gene for prokaryotes and the ITS2 region for fungi. QIIME, a bioinformatic pipeline, was used for data analysis. Our preliminary results revealed significant differences (p-value < 0.05) in fungal and bac¬terial beta-diversity (community composition) and fungal alpha-diversity (species richness) between organic and inte¬grated orchards. Notably, Aureobasidium, Vishniacozyma, and Rhodotorula were the most abundant fungal taxa, while Pseudomonas, Sphingomonas, and Pantoea dominated the bacterial population. Further analyses are needed to confirm correlations between S. vesicarium and disease incidence. Investigating potential negative correlations between previ¬ously identified abundant taxa (e.g., Pseudomonas) and S. vesicarium abundance or disease severity is warranted, con¬sidering their reported biocontrol potential. This study was funded by the Emilia Romagna region within Reg. Law 17 del 27/10/2022. Type of operation “Urgent interventions to support the agricultural, agri-food, fishing and reclamation sectors” Art. 1 “Interventions for innovation in the agricultural and agri-food sector”– Project “A.MA.PERO - Approcci innovativi indirizzati a contrastare la Maculatura bruna del Pero”.