Induction and distribution of amylolytic activity in Cucumis sativus L. in response to virus infection

Inoculation of cucumber (Cucumis sativus L. cv. Laura) cotyledons with tobacco necrosis virus (TNV) causes both qualitative and quantitative changes in the total and fractionated protein extracts as well as in amylolytic activity. Using a specific test it was demonstrated that the virus infection strongly enhances a major band (Rf 0.0645) of amylolytic activity, predominantly located in apoplast space. The accumulation of this extracellular amylolytic activity is regulated by a time-dependent manner and is correlated with the development of necrotic lesions. The amylolytic activity may be related to degradation of starch shown to be accumulated in the immediate vicinity of necrotic lesions associated with the hypersensitive response (HR). The possible biological function of the identified amylolytic activity in the term of ,,pathosmosis" is also discussed.