Abstract
β-Cryptogein, a proteinaceous elicitor from the phytopathogenic fungus Phytophthoracryptogea, is known to induce leaf necrosis in tobacco and non-specific resistance (expressed in the perinecrotic leaf area) against a wide range of tobacco pathogens. To reveal mechanisms underlying the acquired resistance, biochemical changes in leaves of β-cryptogein-elicited tobacco were followed three, five and ten days after elicitation. The activities of peroxidase, β-1,3-glucanase and β-glucosidase, as well as the patterns of acidic pathogenesis-related (PR)-proteins were determined. The protected part (perinecrotic area) and the non-protected part (distant extra-perinecrotic area) of leaves of β-cryptogein-stem treated tobacco (cv. Xanthin.c.) were analyzed. Leaves of water-stem treated tobacco served as controls. It was shown that in the protected leaf part β-cryptogein caused significant metabolic shifts early after elicitation, persisting during the whole period studied. An important increase of peroxidase and β-1,3-glucanase activity was recorded. PR-protein components appeared that were absent in the controls. There were negligible changes in β-glucosidase activity. In the non-protected leaf part late and non-significant changes occurred. Taking into account the antimicrobial, regulatory and structure-modifying properties of the biochemical components studied, it may be admitted that β-cryptogein elicited the development of a hostile environment, i.e. a potential for plant resistance against subsequent pathogen invasion.