The protective effect of Bacillus bacteria against viruses can be significantly expanded by combination with salicylic acid (SA) or methyl jasmonate (MeJ). In soil water deficiency conditions, potato leaves were sprayed with Bacillus subtilis strain 47 combined with MeJ and MeJ + SA displayed a decrease in PVY and preservation of the shoot’s growth. Signaling molecules with Bacillus subtilis mitigated the adverse effect of PVY under water deficiency by manipulating enzymatic/non-enzymatic antioxidant levels and activity in treated plants. The application mixtures increased the mass and number of mini-tubers during the microclonal propagation of plants. Treatment with bacteria in combination with signaling molecules significantly changed the content and phosphorylation status of a number of hydrolases, catalase, phosphorylase, annexin, and protease inhibitor. Based on the analysis of changes in the proteome, the key mechanisms mediating the induction of plant resistance to change in the tuber proteome aimed at enhancing the expression of protective protein genes that increase resistance to pathogens and abiotic stress.

The effect of seed treatment with various materials of chitosan and hydroxycinnamic acids on the growth of barley seedlings was evaluated. It was shown that chitosan-hydroxycinnamic acid conjugates and nanoparticles had no negative effect on the initial stages of the growth of barley seedlings. Adaptation of seedlings after 24 h exposure to 4 % NaCl in the samples of conjugates of 30 kDa chitosan with caffeic and ferulic acids was more effective. There was a decrease in proline contents and restoration of the growth activity under post-stress conditions.

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.