Proteome changes and physiological adaptations of the phytopathogen Xanthomonas citri subsp. citri under salt stress and their implications for virulence

BARCAROLO, MARÍA VICTORIA; GARAVAGLIA, BETIANA S; THOMAS, LUDIVINE; MARONDEDZE, CLAUDIUS; GEHRING, CHRIS; GOTTIG, NATALIA; JORGELINA OTTADO

FEMS MICROBIOLOGY ECOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2019

0168-6496

The bacterium Xanthomonas citri subsp. citri (Xcc) is responsible for the widely distributed disease citrus canker. In the lastyears, Xcc has become a model for the study of plant pathogens, and here we used this bacterium to examine stress on thepathogen during adaptions required for leaf colonization. In the first stages of citrus canker cycle, bacteria encounter lowwater availability and osmotic stress that can affect their maintenance on plant surfaces. To examine such conditions, weconducted a proteome analysis of Xcc grown in culture medium supplemented with 0.25 M sodium chloride and comparedit to control conditions. We found that salt stress induced changes in known stress-induced proteins and also revealednovel stress response proteins. Moreover, some of the bacterial processes associated with bacterial fitness and virulencewere modified under salt stress conditions. In particular, swimming, twitching and surface motilities were decreased, whilebiofilm formation was increased under salt stress. Other adaptations to high salt included reduced bacterial size andincreased survival of bacteria exposed to oxidative stress. Furthermore, expression of type III protein secretion systemrelated genes were augmented under salt stress condition. Our results offer new insight into molecular mechanisms thatgovern phytopathogen adaptation to harsh environments. These adaptations affect life cycle progression which in turninfluences virulence.