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Pantoea stewartii subsp. stewartii Exhibits Surface Motility, Which is a Critical Aspect of Stewart's Wilt Disease Development on Maize

October 2008 , Volume 21 , Number  10
Pages  1,359 - 1,370

Carmen M. Herrera,1 Maria D. Koutsoudis,2 Xiaolei Wang,1 and Susanne B. von Bodman1,2

1Department of Plant Science and 2Department of Molecular and Cell Biology, University of Connecticut, Storrs 06269, U.S.A.

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Accepted 18 June 2008.

Pantoea stewartii subsp. stewartii is a plant-pathogenic bacterium that causes Stewart's vascular wilt in maize. The organism is taxonomically described as aflagellated and nonmotile. We recently showed that P. stewartii colonizes the xylem of maize as sessile, cell-wall-adherent biofilms. Biofilm formation is a developmental process that generally involves some form of surface motility. For that reason, we reexamined the motility properties of P. stewartii DC283 based on the assumption that the organism requires some form of surface motility for biofilm development. Here, we show that the organism is highly motile on agar surfaces. This motility is flagella dependent, shown by the fact that a fliC mutant, impaired in flagellin subunit synthesis, is nonmotile. Motility also requires the production of stewartan exopolysaccharide. Moreover, surface motility plays a significant role in the colonization of the plant host.

Additional keywords:Erwinia stewartii, EsaI/EsaR, virulence, xylem dissemination.

© 2008 The American Phytopathological Society