Ruby Sullan, PhD – Department of Physical & Environmental Sciences, University of Toronto, Scarborough — CSB Seminar

CSB Departmental Seminar

Friday, March 13th @ 11:00 am

SPEAKER: Ruby Sullan, PhD – Department of Physical & Environmental Sciences, University of Toronto, Scarborough

TITLE: Root Attachment and Colonization by Plant Growth-Promoting Rhizobacteria

ABSTRACT: The success of plant growth-promoting rhizobacteria (PGPR) as biofertilizers depends on their ability to attach to, colonize, and persist on plant roots under dynamic environmental conditions. In this seminar, I will present our work on the mechanisms governing early PGPR-root interactions across multiple experimental platforms. Using AFM-based single-cell force spectroscopy, we investigated the primary attachment of individual bacterial cells to different regions of Arabidopsis thaliana roots and identified strain-specific adhesion strategies mediated by long surface polymers, flagella, and physicochemical interactions, including electrostatic and hydrophobic forces. To extend these findings to flow-based environments, we developed a microfluidic root-on-a-chip system that enables real-time monitoring of bacterial accumulation on living roots under continuous flow. Using this platform, we found that both shear conditions and divalent ions influence early bacterial attachment kinetics. I will also discuss how positively charged nanoplastics disrupt these beneficial interactions by coating bacterial surfaces, reducing viability, and inhibiting root colonization. Together, this work provides mechanistic insight into how beneficial bacteria establish on plant roots and how environmental conditions and contaminants shape this process.

HOST: Keiko Yoshioka

LOCATION: Cell and Systems Biology, 25 Harbord Street, Suite 432

LIVESTREAM LINK: https://csb.utoronto.ca/live-stream/