o-Hydroxyethylorutin-mediated enhancement of tomato resistance to Botrytis cinerea depends on a burst of reactive oxygen species

o-Hydroxyethylorutin, when applied exogenously to tomato plants was effective in enhancing resistance to Botrytis cinerea infection. Two tomato cultivars, high and low in susceptibility to B. cinerea , were analysed for superoxide anion, hydroxyl radical, hydrogen peroxide generation rates, for changes in lipid peroxidation and activities in superoxide dismutase, peroxidase and catalase. The reactions observed in uninfected tomato plants, in plants infected with B. cinerea , and in those treated with o-hydroxyethylorutin and infected with the pathogen were compared. The most significant increase in superoxide anion and hydrogen peroxide generation was observed in plants pretreated with o-hydroxyethylorutin and then infected with the pathogen. It was greater and generally occurred earlier in pretreated, less susceptible plants as compared to more susceptible ones. Some decrease in ascorbate peroxidase activity resulting from inoculation with B. cinerea plants pretreated with o-hydroxyethylorutin was observed in studied plants. The results indicate that o-hydroxyethylorutin-induced tomato resistance to B. cinerea infection depends on its stimulation of reactive oxygen species generation and they confirm the important role of enhanced production of ROS in induced plant resistance reactions.