The soil in the close vicinity of Chernobyl Nuclear Power Plant is still heavily contaminated with long-living radioisotopes, such as 137Cs and 90Sr. Doctoral thesis is focused on the investigation of soybean and flax response toward permanently increased level of radiation, using a quantitative high-throughput proteomics approach. During the ontogenesis, investigated plants received the following equivalent doses: a) at the contaminated field - 11.4 cSv flax, 13.2 cSv soybean; b) at the control field - less than 0.4 cSv for both plants. A total protein fraction was isolated from mature (first generation) and developing (second generation) seeds, and analyzed using two-dimensional gel electrophoresis combined with tandem mass spectrometry. All soybean and flax proteins, affected by growth in a radionuclide-contaminated soil during one generation, were sorted into 11 functional categories. Notably, two classes (storage proteins and cell growth) were unique to the first object; on the other hand, four (proteins synthesis, transcription, secondary metabolism and unclassified) - for the second. In the case of a soybean, seed storage proteins showed dominant response to the chronic irradiation. Their complex ambiguous behavior in the contaminated environment of the Chernobyl zone, adds arguments supporting the hypothesis about additional functions of this group. The nonspecific reaction, similar to the heavy metal stress, is another fundamental component of the response to a chronic irradiation. It includes cysteine synthase hyperaccumulation and dehydrins. In addition, data showed that the content of the peroxisomal betaine aldehyde dehydrogenase increased by 30% upon low-dose impact. Several components of signaling pathways are among flax seeds proteins, which changed abundance under the influence of a radionuclide contamination. Lipoxygenase content decreased in the flax proteome grown in the soil contaminated by radionuclides. This may mean that the signaling pathway that includes oxylipins is downregulated; the likely logical consequence is reduced resistance to phytopathogens. Furthermore, we showed lower content of GF14?, a member of the 14-3-3 family of molecular adapters. Additionally, abundance of two glycolytic enzymes - fructose-bi-P aldolase and 3-P-glycerate kinase increased by 50% in flax seeds collected from the contaminated field. Alternative glycolytic reactions in cytoplasm provide metabolic flexibility necessary for plant development and adaptation to environmental stress factors. To improve further our understanding of response to a chronic irradiation we investigated proteome changes during seeds maturation of the second generation of plants grown in experimental areas. Based on data we concluded: proteome changes indicated that soybean had deficit of assimilates for the biosynthesis of seed storage compounds resulted in reduced accumulation of ?-conglycinins. Additionally, citric acid cycle in mitochondria might be activated. For flax, we revealed that chloroplastic pyruvate decarboxylase and ketoacyl synthase had similar patterns of changes: they were more abundant early in the embryogenesis, but their amount decreased in mature seeds. This was accompanied by accumulation of oil in the field at the Chernobyl Nuclear Power Plant exclusion zone The proposed model of onthogenetic reactions to chronic irradiation includes the following components: (i) changes in storage proteins, mediated by transporters (sucrose binding proteins) are specific for soybean; (ii) shifted signaling, which affects alarmones and reversible phosphorylation is unique for flax. On the other hand, activated expression that influences synthesis and packing of proteins (calreticulin and other chaperones), as well as redirection of the primary metabolism (through multifunctional glycolytic enzymes) for the synthesis of glycine betaine, phytochelatins and dehydrins are universal reactions. In the future, our results will help to develop an effective strategy for sustainable crop yield despite of technologically modified environment. Key words: chronic irradiation, radionuclide contamination, Glycine max, Linum usitatissimum, discovery proteomics, two-dimensional gel electrophoresis, primary metabolism rerouting.
