Аннотация:Alternaria alternata is one of the causal agents of the early blight, a dangerous disease of potato and tomato, which is common for almost all regions, where these crops are grown. In this study the virulence and aggressiveness of A. alternata isolates, obtained from the leaves and tubers of potato and leaves and fruits of tomato, has been studied on 13 potato cultivars of different maturity groups and 5 large-fruited tomato cultivars. In the case of two isolates, obtained from tomato leaves and significantly differing in their virulence, the activity of subtilisin- and tripsin-like serine proteases has been also analyzed.
The performed study has revealed intraspecific differences in the virulence and aggressiveness of A. alternata toward the leaves of different potato and tomato cultivars. Some isolates successfully infected cultivars, highly resistant toward other isolates that probably evidences some potato and tomato cultivars have genes of specific resistance to A. alternata.
In addition, the revealed difference in the activity of serine proteases is observed on both interspecific and intraspecific levels and correlated with the virulence and aggressiveness of isolates. A high level of tripsin-like activity of secreted serine proteases is observed in highly pathogenic isolates. Thus, this parameter can be used as a marker for the study of the virulence and aggressiveness of A. alternata isolates.
