A scalable screening approach reveals phylogenetic patterns of bacterial antagonism against potato pathogens
- 1University of Fribourg
Abstract
Microbial biological control agents (mBCAs) offer a promising alternative to conventional disease management, but identifying effective strains requires screening large microbial collections against many pathogens. Here, we developed a scalable screening approach to characterize the antagonistic activity of potato-associated bacteria against multiple pathogens and investigated how bacterial origin and phylogeny relate to antagonistic phenotypes. A collection of 600 bacterial strains isolated from two potato cultivars, three plant compartments using four cultivation media was screened against six major potato pathogens: the bacteria Dickeya solani and Pectobacterium carotovorum, the fungi Alternaria solani and Rhizoctonia solani, and the oomycetes Phytophthora infestans and Pythium ultimum. A scalable confrontation method was developed for non-filamentous bacteria, while complementary lower-throughput assays were used for filamentous strains. This approach enabled successful assessment of 92% of non-filamentous and 97% of filamentous strain-pathogen combinations. Isolation cultivar, plant compartment and cultivation medium had only limited effects on the proportion of antagonistic strains. In contrast, pathogen sensitivity varied markedly: P. infestans was the most susceptible pathogen, whereas D. solani and P. carotovorum were generally resistant to bacterial antagonism. Antagonistic activity clustered phylogenetically, with Bacillus and Streptomyces containing many broad-spectrum inhibitors. In addition, several taxa showed preferential activity against the oomycetes, including P. infestans-specific antagonists from the Pseudomonas genus and P. ultimum-specific antagonists from the Frigoribacterium, Curtobacterium, Pedobacter and Phyllobacterium genera. Overall, multi-pathogen screening revealed distinct generalist and specialist antagonistic profiles and identified candidate strains and taxa for further evaluation as mBCAs.
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BibTeX
@misc{pichon2026scalable,
title = {{A scalable screening approach reveals phylogenetic patterns of bacterial antagonism against potato pathogens}},
author = {V. Pichon and A. Gillon and G. Ruffieux and T. Luethi and C. Morales Undurraga and M. De Vrieze and F. L'Haridon and O. Abdelrahman and L. Weisskopf},
howpublished = {bioRxiv},
year = {2026},
month = sep,
doi = {10.64898/2026.09.22.753498},
url = {https://www.biorxiv.org/content/10.64898/2026.09.22.753498v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - A scalable screening approach reveals phylogenetic patterns of bacterial antagonism against potato pathogens
AU - V. Pichon
AU - A. Gillon
AU - G. Ruffieux
AU - T. Luethi
AU - C. Morales Undurraga
AU - M. De Vrieze
AU - F. L'Haridon
AU - O. Abdelrahman
AU - L. Weisskopf
PY - 2026
DA - 2026/09/22
PB - bioRxiv
DO - 10.64898/2026.09.22.753498
UR - https://www.biorxiv.org/content/10.64898/2026.09.22.753498v1
AB - Microbial biological control agents (mBCAs) offer a promising alternative to conventional disease management, but identifying effective strains requires screening large microbial collections against many pathogens. Here, we developed a scalable screening approach to characterize the antagonistic activity of potato-associated bacteria against multiple pathogens and investigated how bacterial origin and phylogeny relate to antagonistic phenotypes. A collection of 600 bacterial strains isolated from two potato cultivars, three plant compartments using four cultivation media was screened against six major potato pathogens: the bacteria Dickeya solani and Pectobacterium carotovorum, the fungi Alternaria solani and Rhizoctonia solani, and the oomycetes Phytophthora infestans and Pythium ultimum. A scalable confrontation method was developed for non-filamentous bacteria, while complementary lower-throughput assays were used for filamentous strains. This approach enabled successful assessment of 92% of non-filamentous and 97% of filamentous strain-pathogen combinations. Isolation cultivar, plant compartment and cultivation medium had only limited effects on the proportion of antagonistic strains. In contrast, pathogen sensitivity varied markedly: P. infestans was the most susceptible pathogen, whereas D. solani and P. carotovorum were generally resistant to bacterial antagonism. Antagonistic activity clustered phylogenetically, with Bacillus and Streptomyces containing many broad-spectrum inhibitors. In addition, several taxa showed preferential activity against the oomycetes, including P. infestans-specific antagonists from the Pseudomonas genus and P. ultimum-specific antagonists from the Frigoribacterium, Curtobacterium, Pedobacter and Phyllobacterium genera. Overall, multi-pathogen screening revealed distinct generalist and specialist antagonistic profiles and identified candidate strains and taxa for further evaluation as mBCAs.
ER -