Speaker
Description
The aerial surfaces of plants support diverse microbial communities essential to plant function and survival.
The factors that determine where bacteria first attach and grow on plant leaves remain poorly understood. While microbial colonization of the phyllosphere—leaf, stem, and flower surfaces—has been widely studied, most work has focused on later stages shaped by biological and chemical interactions. Here, we isolate the physical contribution by recreating realistic leaf topographies in microfluidic devices and examining bacterial behavior in the absence of biological and chemical cues. We show that purely hydrodynamic interactions with the surface are sufficient to trap motile bacteria in epidermal grooves, guiding early spatial distribution.
Our microfluidic device, developed using two-photon nanolithography and PDMS molding, allows high-resolution imaging of bacterial behavior under controlled conditions.
We observed that motile bacteria, including E. coli and a native phyllosphere isolates such as Pseudomonas syringae, preferentially accumulate in grooves between epidermal cells.
E. coli and P. syringae cells were respectively 39% and 22% more likely to be trapped in grooves than on cell tops.
Over several hours, these regions also hosted significantly larger colonies, with E. coli colony area being 50% greater in grooves than on cell tops.
These findings, paired with mathematical models, illuminate how bacterial motility and hydrodynamic interactions shape microbial colonization patterns on plant surfaces.
More broadly, they contribute to our understanding of how topographical features influence microbiome assembly in living systems.
By enabling controlled, high-resolution observation, our method allows for a mechanistic understanding of biological phenomena that are otherwise difficult to disentangle in vivo.