The content of reactive oxygen species, the activity of key antioxidant enzymes ‒ ascorbate peroxidase and glutathione reductase, the level of expression of the hypersensitive response marker gene (HSR) as well as potato virus X particles content in cv. Uladar seedlings grown on an ion-exchange substrate in the presence of a complex preparation containing chitosan, Bacillus subtilis bacteria-based preparation and salicylic acid, when infected potato virus X. Accumulation of the reactive oxygen species, increase in ascorbate peroxidase activity, a lower level of HSR gene expression and a lower content of virus X particles in potato plants under such conditions are shown. An increase in both the number of potato minitubers and dry matter content in them was also registered when plants were grown on an ion-exchange substrate in the presence of a complex preparation.

The reactive oxygen species content, the activity of phenolic peroxidase, and the expression levels of genes encoding certain defense proteins were studied in potato seedlings grown on a substrate with the addition of a preparation based on B. subtilis and infected with potato virus Х. The accumulation of reactive oxygen species and the induction of the defense system components in potato leaves treated with this preparation and infected are shown. Less viral material was detected in experimental samples of potato seedlings compared with control untreated with B. subtilis.