Pysmenna Y. Adaptive reactions of winter wheat (Triticum aestivum L.) under pathogenesis and its regulation by biotic and abiotic effectors

The thesis is devoted to the investigation of winter wheat (Triticum aestivum L.) adaptive reactions in the plant-pathogen pathosystem under Pseudocercosporella herpotrichoides (Fron) Deighton infection and exogenous regulation by biotic (by Bacillus subtilis 537/Б1 bacterial isolates) and abiotic (by silver and copper nanoparticles) effectors. The qualification work topicality is due to the necessity of deepening research for studying specific and nonspecific reactions of plants under fast-changing environmental conditions in global climatic processes. The overall effect of these changes for the pathogens will largely be determined by the results of pathogen-resistant varieties use and new approaches to control stress reactions of plants with biologically safe plant protection products. Nowadays, agricultural production has huge crop losses due to the influence of various factors. The number of pathogenic stressors for the main agricultural crop – wheat – exceeds 100 diseases. Half of them are fungal diseases. These include eye spot causal agent (cercosporelosis, or cercosporelosis basal rot), caused by the P.herpotrichoides fungus. Eyespot disease causes lodging of wheat, barley, rye, which resulted in 25% of crop losses. Today there are no completely immune varieties to cercosporelosis. Therefore, for our investigation were selected a relatively resistant winter wheat variety Renan. Renan has the Pch1 gene, which is one of the four known genes of resistance to cercosporelosis. To study the plant adaptive responses were also used Myronivska 808 variety, which is characterized by high productivity, but is more susceptible to P.herpotrichoides. However, the genetic variability of the pathogen has been shown for most pathosystems. It undoubtedly should be taken into during development predicting models for climate change impact to plant health in specific habitats. At the same time, the existing experimental models ignore this factor both at the research level within certain climatic zones and on the individual agrocenoses level. Original models of wheat biotic stress caused by P. herpotrichoides and exogenous regulation of its stress responses by Ag and Cu nanosized metals and the B. subtilis bacterial isolates suspension were developed in the presented work. Thus, the study subject is presented by the 3 model systems: plant-pathogen, plant-pathogen + abiotic effector (nanoparticles) and plant-pathogen + biotic effector (bacteria). Our investigation considers the understudied relationships of defense mechanisms using appropriate markers of stress tolerance at the cellular, tissue, and organism levels that are likely to be involved in the plant adaptive responses. However, their manifestation specificity at the phenotypic or metabolic level remains unknown for a specific coincidence of stressors. It was studied the whole organism morphometric parameters such as tissues water supply – as the first "visual" indicators of the biotic stressors action; the activity of specific PR-proteins – lectin-like proteins of different cellular compartments, which play an important role in the formation of plant protective reactions to the pathogen; biochemical markers – the content of the TBA-reactive substances (a marker of the oxidative stress development), catalase and superoxide dismutase activity (important antioxidant enzymes). The cellular and organ specificity of the stress reactions development of wheat seedlings aboveground and underground parts under pathogen defeat was determined. The obtained results of studies on the adaptive reactions of winter wheat in three model systems showed the functional orientation of regulatory systems of different wheat genotypes under P. herpotrichoides infection and the effect of Ag, Cu biocidal metal nanoparticles, or B. subtilis bacterial isolates.