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Evidence of a Multicopper Oxidase in Mn Oxidation by Gaeumannomyces graminis var. tritici

February 2006 , Volume 96 , Number  2
Pages  130 - 136

Ian A. Thompson , Don M. Huber , and Darrell G. Schulze

First and second authors: Department of Botany and Plant Pathology, Purdue University, 915 State Street, Lilly Hall, West Lafayette, IN 47907; and third author: Department of Agronomy, Purdue University, 915 Lilly Hall, West Lafayette, IN 47907

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Accepted for publication 31 August 2005.

Manganese (Mn) oxidation by the plant-pathogenic fungus Gaeumannomyces graminis var. tritici has been correlated with virulence in take-all disease. The mechanism of Mn oxidation has not, however, been investigated adequately. Research on bacteria and other fungi indicates that Mn oxidation is most often the result of the activity of multicopper oxidases. To determine if G. graminis var. tritici oxidizes Mn by similar means, the Mn oxidizing factor (MOF) produced by G. graminis var. tritici was characterized by cultural, spectrophotometric, and cellulose acetate electrophoresis methods. Based on our results, the MOF is an extracellular enzyme with an estimated molecular weight of 50 to 100 kDa. Electrophoresis and spectrophotometry indicate that the MOF is a multicopper oxidase with laccase activity.

© 2006 The American Phytopathological Society