Two Apoplastic alpha-Amylases Are Induced in Tobacco by Virus Infection.
alpha-Amylase activity (EC 3.2. 1.1) is greatly increased in leaves of tobacco (Nicotiana tabacum L. cv Samsun NN) infected with tobacco mosaic virus (TMV). The kinetics of enzyme induction during the hypersensitive reaction resemble those of other hydrolases known to be pathogenesis-related proteins of tobacco. Two alpha-amylases were purified from TMV-infected leaves and shown to have features in common with well-characterized pathogenesis-related proteins: they are acidic monomers that can be separated upon electrophoresis on basic native gels, and they are found in the apoplastic compartment of the cell. This extra-cellular localization was demonstrated by comparing the alpha-amylase partition between the intercellular wash fluid and the cell extract with that of proteins of known cellular compartmentalization. These data indicate an active secretion of both alpha-amylases produced in tobacco upon TMV infection.
Heitz
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Institut de Biologie Moléculaire des Plantes du Centre National de la Recherche Scientifique, Université Louis Pasteur, 12 rue du Général Zimmer 67084 Strasbourg Cédex, France.
Geoffroy
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Fritig
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Legrand
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