Formation of the hypersensitivity response due to the expression of <Emphasis Type="Italic">FeSOD1</Emphasis> gene in tomato when it is inoculated with <Emphasis Type="Italic">Phytophthora infestans</Emphasis>

The activity of antioxidant enzymes and ultrastructural changes in tissues inoculated with P. infestans isolate have been studied in the previously developed independent transgenic lines of tomato with FeSOD1 gene and control plants. It is shown that the activity of superoxide dismutase is significantly higher in transgenic plants than that in control plants (nontransgenic plants). Chlorosis and obvious changes in tissue turgor were observed when the control tomato plants were inoculated, which indicates irreversible damages and unimpeded progression of infection. At the same time, the transgenic lines were characterized by the formation of clearly limited zones of damaged cells that rapidly arrested the infection. In addition, the damages differed from those in nontransgenic plants: the cells along the edges of the infection site were smaller and had heavy invaginations of the cell wall. The contacts between the cells were disrupted in this zone, but they were preserved in undisturbed zones of the tissue. Thus, the expression of the FeSOD1 transgene promotes the emergence of the resistance to P. infestans in tomato transgenic plants.