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We studied the effect of signaling molecules – stress phytohormones of salicylic (SA) and jasmonic (JA) acids, on the resistance of calluses and potato tubers to late blight pathogen – oomycete Phytophthora infestans (Mont.) De Bary and the pathogen's ability to synthesize and secrete proteolytic enzymes that cause it properties. The introduction of SA and JA into the callus cultivation medium inhibited the growth of P. infestans and altered the mycelium morphology. Microscopic observations showed that infection of potato tubers led to the appearance of dead (necrotic) cells. So, 48 hours after inoculation, there was 24.6 ± 1.1% of dead cells in the tubers of the susceptible cultivar, 9.8 ± 0.9% in the tubers of the stable cultivar, and only 17.2 ± 0.7 and 16.3 ± 0.8% in the susceptible cultivars pretreated with SA and JA. It is shown that oomycete P. infestans produces mainly serine proteases with a maximum level of activity at neutral and slightly alkaline pH, and a temperature optimum of 50 °C. Based on the analysis of substrate specificity, they were assigned to trypsin-like proteases. The treatment with SA and JA significantly increased the transcriptional activity of the serine protease inhibitor gene in both healthy and late blighted potato tubers. The data obtained suggest a wide adaptive plasticity of the late blight pathogen, as well as prospects for the development and use of new antimicrobial biological products in combination with stress phytohormones to protect potatoes from P. infestans. [ABSTRACT FROM AUTHOR]

Cereal aphids (Aphididae) are considered one of the main pests of wheat. Recently, studies have shown that many members of the genus Bacillus can effectively reduce the pest number on plants. The lipopeptide production of bacteria may be involved this process. We have identified the surfactin-synthetase gene in strain B. subtilis 26D and isolates Bacillus sp. Tas-1 and Tas-8.2, the iturin-synthetase gene in strains B. subtilis 11VM and B. thuringiensis B- 6066. In addition, the fengicine-synthetase gene was identified in strain B. thuringiensis B-6066. We have shown that all 5 strains and isolates of Bacillus spp. and their lipopeptides had a growth-promoting effect and increased seed germination. In addition, treatment of plants with cells of bacterial strains or their metabolites accelerated the growth of 1st and 2nd leaves of wheat, both under normal conditions and during the colonization of aphids. Our results showed that the bacteria Bacillus spp. and their metabolites indirectly influenced the mortality of S. graminum feeding on treated wheat plants. Thus, the growth-promoting activity of strains and isolates of Bacillus spp. did not depend on the class of lipopeptide synthesized by these bacteria. However, the type of lipopeptide synthesized was important in the indirect effect of bacteria on the viability of the greenbug aphid. Strains and isolates synthesizing surfactin (B. subtilis 26D, Bacillus sp. Tas-1 and Tas-8.2.) and fengicin (B. thuringiensis B-6066), but not iturin (B. subtilis 11VM), had the greatest indirect effect on the viability of the S. graminum and endurance of wheat plants. Bacterial lipopeptides may be involved in increasing plant tolerance to the pest. [ABSTRACT FROM AUTHOR]