The effect of pre-sowing plasma seed treatment of maize ( Zea mays L.), narrow-leaved lupine ( Lupinus angustifolius L.) and winter wheat ( Triticum aestivum L.) on seed germination, plant resistance to common diseases during vegetation and crop yield is studied in laboratory and field experiments. It is shown the efficiency of seed treatment by low-pressure radio frequency plasma in suppression of a number of fungal crop diseases such as boil smut of maize, root rot of lupine and winter wheat at different growth stages. At the stage of V9 (9th leaf visible) the infection level in maize plants from treated seeds was 3 times less than that in control. Root rot disease development of lupine at the first stages (3rd–4th leaves emerged) of growth did not exceed 6.9% in plants from the treated seeds while reached to 47.8% in control. Pre-sowing seed treatment led to suppress the anthracnose spreading on narrow-leaved lupine up to the flowering stage. It was revealed that, due to a decrease in the level of seed infection, stimulation of field germination, early seedling growth and plant resistance to pathogens during the vegetation period, the winter wheat grain yield increased by 2.3%, maize—by 1.7%, narrow–leaved lupine—by 26.8% compared to control plants. Increases in activity of non-enzymatic antioxidants (proline, anthocyanins as well as total phenolic content) in roots of maize seedling were observed which may indicate a significant role of plasma seed treatment in improving the plant resistance to biotic and abiotic stress during the vegetation.

Viral diseases of potatoes are among the main problems causing deterioration in the quality of tubers and loss of yield. The growth and development of potato plants largely depend on soil moisture. Prevention strategies require comprehensive protection against pathogens and abiotic stresses, including modeling the beneficial microbiome of agroecosystems combining microorganisms and immunostimulants. Chitosan and its derivatives have great potential for use in agricultural engineering due to their ability to induce plant immune responses. The effect of chitosan conjugate with caffeic acid (ChCA) in combination with Bacillus subtilis 47 on the transcriptional activity of PR protein genes and changes in the proteome of potato plants during potato virus Y (PVY) infection and drought was studied. The mechanisms of increasing the resistance of potato plants to PVY and lack of moisture are associated with the activation of transcription of genes encoding PR proteins: 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), as well as qualitative and quantitative changes in the plant proteome. The revealed activation of the expression of marker genes of systemic acquired resistance and induced systemic resistance under the influence of combined treatment with B. subtilis and chitosan conjugate indicate that, in potato plants, the formation of resistance to viral infection in drought conditions proceeds synergistically. By two-dimensional electrophoresis of S. tuberosum leaf proteins followed by MALDI-TOF analysis, 10 proteins were identified, the content and composition of which differed depending on the experiment variant. In infected plants treated with ChCA, the synthesis of proteinaceous RNase P 1 and oxygen-evolving enhancer protein 2 was enhanced in conditions of normal humidity, and 20 kDa chaperonin and TMV resistance protein N-like was enhanced in conditions of lack of moisture. The virus coat proteins were detected, which intensively accumulated in the leaves of plants infected with potato Y-virus. ChCA treatment reduced the content of these proteins in the leaves, and in plants treated with ChCA in combination with Bacillus subtilis, viral proteins were not detected at all, both in conditions of normal humidity and lack of moisture, which suggests the promising use of chitosan derivatives in combination with B. subtilis bacteria in the regulation of plant resistance.

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.

Исследованы физиолого-биохимические параметры проростков кукурузы после выдерживания семян, предварительно подвергнутых кратковременному воздействию высокочастотного (ВЧ) электромагнитного поля (ЭМП) и плазмы ВЧ разряда, в контролируемых оптимальных и неблагоприятных условиях хранения. При оптимальных условиях хранения предварительная обработка семян плазмой и ЭМП стимулировала рост и развитие проростков, содержание пролина соответствовало таковому у необработанных семян (оптимальный контроль) или несколько снижалось, общая активность пероксидазы увеличивалась. Ускоренное старение контрольных семян в течение 3 сут (стрессовый контроль) вызвало повышение электропроводности их экссудатов и замедление роста проростков на фоне увеличения содержания пролина и усиления пероксидазной активности. В экспериментальной группе с предварительной обработкой семян ЭМП исследуемые показатели сохранялись на уровне оптимального контроля, хотя пероксидазная активность была выше, чем у проростков из оптимального и стрессового контроля. У проростков, выросших из обработанных плазмой семян, наряду с замедлением роста отмечалось сохранение высокой пероксидазной активности и увеличение накопления пролина. В результате ускоренного старения в течение 7 сут всхожесть семян, обработанных плазмой, снижалась практически в 2 раза, значительно тормозилось прорастание, наблюдалось ингибирование активности пероксидазы в клетках корней. Содержание пролина в обработанных ЭМП образцах возросло на 51,8 %, а в обработанных плазмой – в 3 раза по сравнению с оптимальным контролем. Так как уровень пролина возрастает пропорционально увеличению степени и продолжительности воздействия неблагоприятных условий хранения, предполагается, что его накопление в проростках свидетельствует скорее о степени воздействия повреждающего фактора, а не о проявлении устойчивости к нему. Анализ эффективности различных режимов предпосевной обработки семян кукурузы показал, что воздействие ВЧ ЭМП на эту культуру может выступать индуктором повышения резистентности организма, обеспечивая сохранение физиологического качества семян при хранении и поддержание скорости роста растений или их выживание.

The effect of epibrassinolide in combination with salicylic acid and methyl jasmonate on the formation of complex resistance of clonally micropropagated potato plants of the Briz variety to the potato virus Y and to moisture lack, their physiological state, the functioning of the pro-/antioxidant system, as well as on the productivity and quality of the obtained mini-tubers was studied. It was revealed that antiviral resistance under combined stress conditions is formed only in the presence of epibrassinolide that triggers a series of protective mechanisms through accumulation of hydrogen peroxide, phenolic compounds and an increase in peroxidase activity, while maintaining productivity and improving the quality of the products obtained. The use of a three-component mixture is accompanied by the largest mass and a number of potato minitubers, while its protective effect against a viral infection is not manifested.

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.