Role of Exopolysaccharides in Resistance to Hydrogen Peroxide and Virulence of Agrobacterium Tumefaciens (2023)

Undergraduates: Isabelle Dalton, Caroline Chandler

Faculty Advisor: Ann Matthysse
Department: Biology

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Agrobacterium tumefaciens is a gram-negative soil bacterium found in the rhizosphere. If a plant is wounded, the bacteria infect the wound and transfer a piece of DNA to the host cells to induce the formation of crown gall tumors. As part of their defense against pathogens, plants produce reactive oxygen species including hydrogen peroxide. Exopolysaccharides play a role in producing a biofilm that helps protect A. tumefaciens from plant hosts' defense mechanisms like hydrogen peroxide. Some A. tumefaciens mutants that fail to produce certain exopolysaccharides show reduced resistance to hydrogen peroxide and reduced virulence on tomato stems, Bryophyllum daigremontiana leaves, and Pyrus communis fruit discs. Based on these data, succinoglycan and the unipolar polysaccharide are not important in resistance to hydrogen peroxide, transient transformation, and virulence.

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