Kovalenko M. Drought stress tolerance of Triticum L. plants by the parameters of biochemical phenotyping

The thesis is focused on the biochemical phenotyping of drought stress tolerance of common wheat (Triticum aestivum L.) and emmer (T. dicoccum Schrank ex Schübl.) plants. It was established, that wheat genotypes, selected after screening using osmotic stress model system, have a different reaction on stress varying in the oxidative homeostasis characteristics, the specifics of the dehydrin accumulation and the activity of chitinase and β-1,3-glucanase enzymes. In particular, the development of oxidative processes, the inhibition of antioxidant enzyme activities and the decrease of the dehydrin content with a molecular weight of 57 and 30 kD were observed in common wheat of cv. Trypilska under the stress induced by polyethylene glycol, indicating on the drought sensitivity of given cultivar. Common wheat of cv. Favorytka had a higher tolerance to short-term osmotic stress, probably due to the accumulation of osmotically active compounds, in particular, proline and dehydrins. At the same time, the inhibition of the catalase activity in the cv. Favorytka was observed under the prolonged stress conditions which may contribute to the development of the oxidative processes due to the accumulation of hydrogen peroxide. The obtained results show the implementation of the genetic potential of drought tolerance of common wheat of cv. Holikovska, where development of oxidation processes and inhibition of antioxidant defense systems under prolonged stress conditions were not detected. Support of redox homeostasis in emmer plants under osmotic stress conditions is likely to be provided by effective osmoregulation and the functioning of proteins that mediate the stability of protein molecules and plasma membranes. This is confirmed by the accumulation of proline, 30 kDa dehydrin and the induction of 23 kDa β-1,3-glucanases activity. The complex analysis of antioxidant defense systems using a highly sensitive method for determining the peroxisome abundance allow measuring the drought tolerance of 6 genotypes of common wheat, which indicates the promising use of this analysis for biochemical phenotyping of agricultural plants. Correlation analysis between the components of the redox system and photosynthetic parameters allowed to reveal a stable relationship between the content of peroxisomes, hydrogen peroxide and TBA-reactive substances, which is consistent with the hypothesis of ROS-induced peroxisome proliferation. The perspectives of using biogenic metal nanoparticles as the inducers of plant protective reactions, in particular – an antioxidant system, which promotes the productivity of cereal crops, was demonstrated.