Research

Bacterial pathogens utilize secreted proteins to colonize plants

The plant apoplast, the space between cells spanning from membrane to membrane, is one of the first points of contact and a niche for many pathogenic microbes. Plants monitor the apoplast via cell surface receptors, and upon recognition of a threat, they convert the apoplast into an unfriendly environment, secreting plant proteases, protease inhibitors, defense compounds etc.  For hemibiotrophic/biotrophic phytopathogens, which may live in this environment for extended periods of time, controlling the apoplastic environment is essential. This is achieved through the secretion of toxins and proteins, either directly into plant cells or into the apoplast via secretion systems.

The study of type II-secreted proteins in the apoplast

Xanthomonas is a genus of Gram-negative bacteria that colonizes the apoplast of hundreds of economically and socially valuable plant species across the world. The type II secretion system ejects proteins into the apoplast, manipulating the bacteria’s immediate environment. Although it has been established as an important virulence factor for Xanthomonas, as well as for many other bacterial phytopathogens, there are still significant gaps in our understanding of how type II secretion is regulated, exactly what proteins are released and their contributions to bacterial survival and plant immune activation in the apoplast. Our lab aims to address these questions utilizing molecular biology, biochemistry, protein modeling and evolutionary biology approaches, mostly working with Xanthomonas strains infecting tomato, pepper, Arabidopsis thaliana, and Nicotiana benthamiana plant model systems.