Poster
Jonathan M. Jacobs
The Ohio State University
Columbus, Ohio, United States
Jelmer Poelstra
The Ohio State University
Wooster, Ohio, United States
Zachary Konkel
The Ohio State University
Columbus, Ohio, United States
Jules Butchacas
The Ohio State University
Columbus, Ohio, United States
Verónica Román-Reyna
The Pennsylvania State University
University Park, Pennsylvania, United States
Lillian Ebeling-Koning
The Ohio State University
Columbus, Ohio, United States
Rebecca Curland
University of Minnesota
St. Paul, Minnesota, United States
Ruth Dill-Macky
University of Minnesota
St. Paul, Minnesota, United States
Cindy Morris
INRAE
Montfavet, Provence-Alpes-Cote d'Azur, France
Environmental transmission is critical for many pathogenic microorganisms to reach their hosts although the underlying genetics are poorly understood. Biological ice nucleation is a biophysical process where organisms facilitate water freezing near subzero temperatures. Some bacteria use protein InaZ for the formation of and movement in precipitation. In general the genetics that drive microbial transmission remain poorly understood. Here we investigated the link between inaZ evolution and pathogen transmission strategies. Our phylogenomic analysis found that inaZ is ancestral to Gammaproteobacteria and convergently lost from multiple species that are now ice nucleation inactive. Loss across three plant-associated genera, Xanthomonas, Pseudomonas and Pantoea, occurred from frameshift mutations and insertion sequence transposable elements, which directly disrupted inaZ. Lineages that lost inaZ now rely on plant- or insect-mediated transmission. We determined that inaZ loss correlated with significant genome-wide gene loss and reduced gene flow within these species. These mirror patterns observed in island biogeography where organisms become geographically isolated. Overall these results highlight gene loss as a key driver of transmission strategy evolution.