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The effect of chitosan–caffeic acid (Ch–CA) conjugate separately and in combination with a mixture of Bacillus subtilis 47 on the plant defense against PVY under optimal hydration and water deficit in soil was evaluated. The treatments of Ch–CA and Ch–CA+B. subtilis 47 on healthy potato plants under optimal soil moisture conditions demonstrated the accumulation of proline and phenolic compounds, as well as the activation of PPO, which collectively led to an increase in the nonspecific plant defenses. The application of Ch–CA resulted in a reduction of PVY infection in potato plants grown under both optimal and soil moisture-deficient conditions and led to an increase in the potato mini-tuber's mass. The combination of B. subtilis 47 and Ch–CA proved effective in reducing the infection level exclusively under conditions of soil water deficit. It has been demonstrated that the primary factor influencing the development of resistance in potato plants to PVY under moisture-limiting conditions is associated with an elevated peroxidase activity and alterations in antioxidant activity within plant tissues. [ABSTRACT FROM AUTHOR]

The effect of chitosan conjugates with caffeic (ChCA) and ferulic (ChFA) acids in combination with Bacillus subtilis bacteria on the transcriptional activity of PR protein genes and proteome changes in potato plants during infection with Phytophthora infestans (Mont.) de Bary was studied. Plants grown from mini tubers of the Udacha variety were sprayed with solutions of ChCA and ChFA, a suspension of B. subtilis bacteria strains 26D and 11 VM, and conjugates of ChCA of ChFA together with bacteria. At 3 days after treatment, some plants were infected with P. infestans. A decrease in the degree of development of the late blight pathogen on potato leaves in all treatment options was revealed. The maximum protective effect was manifested when plants were treated with the B. subtilis strain 26D bacteria in combination with conjugates of chitosan and oxycinnamic acids. The mechanisms of increasing the resistance of potato plants to P. infestans were associated with the activation of transcriptional activity of genes encoding the main protective protein (PR-1), chitinase (PR-3), thaumatin-like protein (PR-5), protease inhibitor (PR-6), peroxidase (PR-9), and ribonuclease (PR-10). The revealed activation of the expression of marker genes of systemic acquired resistance and induced systemic resistance under the influence of joint treatment of plants with B. subtilis and chitin conjugates with hydroxycinnamic acids indicates the synergistic development of protective reactions in potato plants in this variant. Using the method of two-dimensional electrophoresis of S. tuberosum leaf proteins followed by MALDI-TOF analysis 12 proteins were identified; their presence in the leaves differed depending on the variant of the experiment. In all treatment variants, serine–threonine protein phosphatase activity was suppressed, reflecting the development of the hypersensitivity reaction. Different variants of the experiment formed weakly expressed clusters, which indicates multiple mechanisms of regulation of the synthesis of protective proteins involved in the reaction to treatment with bacteria, chitosan conjugates, and infection with P. infestans. [ABSTRACT FROM AUTHOR]

Correlation analysis was used to assess the level of correlation between plant resistance to late blight and the content and activity of components of the antioxidant system and protective proteins in plants grown under conditions of lack of moisture and under normal conditions. A direct relationship between the degree of plant damage and the expression level of the proline synthase gene, which, in addition to hydrolase inhibitors, is obviously one of the indicators of plant stress, has been revealed. In general, the expression levels of the proline synthase and PR-6 genes, as well as antihydrolytic activity in leaves, show the most pronounced relationship between themselves and with the degree of plant damage. Also, according to the results of factor analysis, the level of expression of methyltransferase, the activity of peroxidase and cellulase are interrelated. Various treatment options with bacteria and their mixtures with signaling molecules had a similar effect on the activity of protease and amylase inhibitors, as well as the expression level of PR-1, PR-5, PR-6 and proline synthase genes both during phytophthora infection and under conditions of lack of moisture. The expression levels of PR-5, proline synthase, and the activity of amylase inhibitors showed similar changes under the appropriate treatments also under normal conditions; apparently, the change in these indicators is a manifestation of universal plant reactions to treatment with bacteria and signaling molecules. It can be concluded that the expression of genes and the subsequent manifestation of the activity of protease inhibitors, as well as the expression of the gene of the main antimicrobial protein, can be considered as common ways to implement plant resistance, activated under the influence of treatment by bacteria and signaling molecules, both under abiotic and biotic stress. [ABSTRACT FROM AUTHOR]

The effect of Bacillus subtilis bacteria in combination with salicylic (SA) and jasmonic (JA) acids on changes in the proteome of potato leaves during infection with Phytophthora infestans (Mont.) de Bary and moisture deficit was studied. Plants grown from microtubers of the Rannyaya Roza variety were sprayed with a suspension of B. subtilis (108 cells/mL) and a mixture of bacteria with SA (10–6 M), JA (10–7 M), and SA + JA. The plants were infected with P. infestans (105 spores/mL) 3 days after treatment and cultivated under conditions of artificial soil drought by reducing watering. When the soil moisture reached 40 ± 5% of the total water capacity (7 days after infection), the plants were fixed in liquid nitrogen to isolate proteins and analyze them by two-dimensional electrophoresis and mass spectrometry. A decrease in the degree of infestation with P. infestans was shown when potato leaves were treated with B. subtilis in combination with SA and JA. The leaf proteome shows differences in the content of 14 proteins in the pI range from 4.0 to 9.0 with molecular masses from 30 to 125 kDa. The most significant changes in the spectrum of plant proteins were found in healthy plants treated with B. subtilis and in infected plants in the combination of B. subtilis with JA. Qualitative and quantitative changes were observed for proteins involved in the processes of respiration and hypersensitivity reactions (HSR), energy metabolism, synthesis of secondary metabolites, and protective proteins that affect plant resistance to abiotic and biotic stress. Proteomic analysis has identified important proteins involved in the mechanism of potato responses to treatment with B. subtilis and infection with P. infestans, although the exact functions of the identified proteins and their potential impact on potato plant resistance to P. infestans and moisture deficit remain to be elucidated. [ABSTRACT FROM AUTHOR]

The joint effect of Bacillus subtilis 26D endophytic bacteria and chitooligosaccharides (COSs) on the resistance of potato plants (Solanum tuberosum L.) to the late blight causative agent Phytophthora infestans (Mont.) De Bary was studied. A twofold decrease in the area of late-blight lesions on potato leaves was revealed during the joint presowing treatment of minitubers with B. subtilis bacteria (108 cells/mL) with COSs (1 mg/L). Treatment with COSs was found to have similar protective effect on potato plants, but this was not observed with the use of only bacteria. The mechanisms of increased potato-plant resistance to P. infestans were associated with the activation of catalase, peroxidase, and hydrolases (amylase and protease) inhibitors, the accumulation of hydrogen peroxide, and transcripts of genes encoding PR proteins: amylase inhibitor, basic protective protein (PR-1), chitinase (PR-3), protease inhibitor (PR-6), peroxidase (PR-9). The revealed activation of the gene expression of the main antimicrobial protein PR-1 (a marker of the development of systemic acquired resistance) and PR-6 (a marker of the development of induced systemic resistance) under the influence of combined treatment with B. subtilis and COSs indicates that the development of protective reactions in potato plants to the late blight pathogen in this case occurs synergistically, with the participation of various signaling pathways, in which B. subtilis prime protective genes, and COSs act as a trigger for their expression. [ABSTRACT FROM AUTHOR]

The effect of the bacteria Bacillus subtilis in combination with salicylic (SA) and jasmonic (JA) acids on the state of the pro/antioxidant system (the content of hydrogen peroxide, the activity of catalase, peroxidase, superoxide dismutase), the transcriptional activity of the genes PR-1, PR-6, and PR-9, and changes in the leaf proteome in connection with the development of potato resistance to the causative agent of late blight, the oomycete Phytophthora infestans (Mont.) de Bary, upon a moisture deficiency was studied. Plants grown from microtubers were sprayed with a suspension of B. subtilis (108 cells/mL) and a mixture of bacteria with SA (10–6 M), JA (10–7 M), SA + JA. Three days after treatment, the plants were infected with P. infestans (105 spores/mL) and cultivated under artificial soil drought conditions created with a reduction in irrigation. The biochemical parameters in plants were assessed when the soil moisture reached 40 ± 5% of full moisture capacity (7 days after infection). A decrease in the degree of P. infestans development on leaves was detected upon treatment with B. subtilis in combination with SA and JA. The mechanism of the activation of the defense systems of potato plants by bacteria of the genus Bacillus and signaling molecules under drought conditions was associated with the accumulation of H2O2, an increase in the activity of antioxidant enzymes, and the expression of PR-protein genes. In the proteome of potato leaves, differences were found in the presence of 19 polypeptides in the pI range from 4.0 to 9.0 with molecular weights from 30 to 125 kDa. Treatment with B. subtilis in combination with JA most significantly changed the protein spectra in both healthy and infected plants. The revealed differences in the activation of the synthesis of protective proteins under the influence of B. subtilis bacteria and signaling molecules indicate the existence of differential pathways for the formation of resistance to P. infestans in potato plants with their participation. [ABSTRACT FROM AUTHOR]