Tiffany Lowe-Power

Date & Time: September 16, 2024, at 4 pm

Location: BCH 101

Zoom: https://msu.zoom.us/j/91993518218?pwd=SzN0Umd0dElSblVSOGJEY2U0UzJJdz09
Meeting ID: 919 9351 8218
Passcode: 028299

Host: Michelle Hulin

About the Speaker

Institution: University of California, Davis

Subject: Why are Ralstonia wilt pathogens goopy?

Abstract: Like most plant-colonizing bacteria, Ralstonia wilt pathogens secrete an exopolysaccharide. Ralstonia mutants that cannot produce the EPS-I exopolysaccharide have long been known to be impaired in virulence, but the biological role of EPS-I has remained unknown. Here, we investigate the viscoelastic properties of Ralstonia colony biofilms. Most bacterial and yeast colony biofilms have elastic-dominated mechanical behavior. In contrast, Ralstonia colony biofilms are uniquely viscous-dominant, allowing the colonies to flow in response to gravity or shear stresses. Phylogenomic analysis reveals that EPS-I biosynthesis and export is an evolutionary innovation that is ancestral to wilt pathogenesis in the Ralstonia genus. Our results suggest that EPS-I production is a key evolutionary adaptation that enables Ralstonia’s explosive growth in planta and rapid disease progression. Thus, we propose that Ralstonia wilt pathogens evolved to produce a unique, viscous-dominant viscoelastic exopolysaccharide as a cooperative mechanism for in planta mobility.