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Pantoea stewartii subsp. stewartii Produces an Endoglucanase That Is Required for Full Virulence in Sweet Corn

April 2012 , Volume 25 , Number  4
Pages  463 - 470

Mojtaba Mohammadi, Lindsey Burbank, and M. Caroline Roper

Department of Plant Pathology and Microbiology, 900 University Avenue, University of California, Riverside 92521, U.S.A.

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Accepted 20 November 2011.

Pantoea stewartii subsp. stewartii, a xylem-dwelling bacterium, is the causal agent of Stewart's wilt and blight of sweet corn. The goal of this study was to characterize the only gene in the P. stewartii subsp. stewartii genome predicted to encode an endoglucanase (EGase); this gene was designated engY. Culture supernatants from P. stewartii subsp. stewartii and Escherichia coli expressing recombinant EngY protein possessed both EGase and xylanase activities. Deletion of engY abolished EGase and xylanase activity, demonstrating that EngY appears to be the major EGase or xylanase produced by P. stewartii subsp. stewartii. Most importantly, our results show that EngY contributes to movement in the xylem and disease severity during the wilting phase of Stewart's wilt but is not required for water-soaked lesion formation.

© 2012 The American Phytopathological Society