Document Type
Article
Journal/Book Title/Conference
The ISME Journal: Multidisciplinary Journal of Microbial Ecology
Volume
19
Issue
1
Publisher
Oxford University Press
Publication Date
1-30-2025
Journal Article Version
Version of Record
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.
First Page
1
Last Page
13
Abstract
Pantoea agglomerans is one of four Pantoea species reported in the USA to cause bacterial rot of onion bulbs. However, not all P. agglomerans strains are pathogenic to onion. We characterized onion-associated strains of P. agglomerans to elucidate the genetic and genomic signatures of onion-pathogenic P. agglomerans. We collected > 300 P. agglomerans strains associated with symptomatic onion plants and bulbs from public culture collections, research laboratories, and a multi-year survey in 11 states in the USA. Combining the 87 genome assemblies with 100 high-quality, public P. agglomerans genome assemblies we identified two well-supported P. agglomerans phylogroups. Strains causing severe symptoms on onion were only identified in Phylogroup II and encoded the HiVir pantaphos biosynthetic cluster, supporting the role of HiVir as a pathogenicity factor. The P. agglomerans HiVir cluster was encoded in two distinct plasmid contexts: (i) as an accessory gene cluster on a conserved P. agglomerans plasmid (pAggl), or (ii) on a mosaic cluster of plasmids common among onion strains (pOnion). Analysis of closed genomes revealed that the pOnion plasmids harbored alt genes conferring tolerance to Allium thiosulfinate defensive chemistry and many harbored cop genes conferring resistance to copper. We demonstrated that the pOnion plasmid pCB1C can act as a natively mobilizable pathogenicity plasmid that transforms P. agglomerans Phylogroup I strains, including environmental strains, into virulent pathogens of onion. This work indicates a central role for plasmids and plasmid ecology in mediating P. agglomerans interactions with onion plants, with potential implications for onion bacterial disease management.
Recommended Citation
Gi Yoon Shin, Jo Ann Asselin, Amy Smith, Brenna Aegerter, Teresa Coutinho, Mei Zhao, Bhabesh Dutta, Jennie Mazzone, Ram Neupane, Beth Gugino, Christy Hoepting, Manzeal Khanal, Subas Malla, Claudia Nischwitz, Jaspreet Sidhu, Antoinette Machado Burke, Jane Davey, Mark Uchanski, Michael L Derie, Lindsey J du Toit, Stephen Stresow-Cortez, Jean M Bonasera, Paul Stodghill, Brian Kvitko, Plasmids encode and can mobilize onion pathogenicity in Pantoea agglomerans, The ISME Journal, Volume 19, Issue 1, January 2025, wraf019, https://doi.org/10.1093/ismejo/wraf019