Chumakova V. Phytohormonal and trophic regulation of the vernalization process of winter wheat in vivo and in vitro.

The dissertation is devoted to find out the allelic state of Vrn genes, the patterns of vernalization processes in soft winter wheat sprouts under contrasting conditions of trophic support, as well as the priming of gibberellin (HA) under these conditions. The allelic state of Vrn genes in vitro, their effects on morphogenesis during vernalization and the influence of HA on morphogenetic processes in callus of winter wheat varieties have been studied. The differences in the allelic state of Vrn genes have been found that caused different rates of plant development of wheat isogenic lines. The natural and artificial trophic support of sprouts at the end of the vernalization period have caused a change in the allelic state of the Vrn-B1b locus, the main repressor of winter wheat development. Contrasting conditions of trophic support of the vernalization process and HA priming have determined the intensity of growth processes, cell proliferation, carbohydrate metabolism and rates of plant development. Thus, trophic factors and phytohormones are a necessary and sufficient factor for passing of vernalization processes and winter wheat development. In vitro culture, the allelic state of Vrn genes has not changed compared to their state in vivo. During the 45 days of vernalization, morphogenetic processes intensified in the callus culture of winter wheat. The Vrn gene system is stable, and in vitro culture is a reliable and adequate model for studying the patterns of morphogenesis of soft wheat. The addition of HA to the nutrient regenerating medium for cultivating of calluses in vitro has caused changes in the intensity of morphogenetic processes depending on the phytohormone concentration. It is stated that phytohormones and trophic processes are necessary factors to provide the normal passing of vernalization processes, the expression of Vrn genes, which ultimately determines the rates of development of soft wheat. Key words: soft wheat (Triticum aestivum L.), isogenic lines, Vrn genes, gibberellin, vernalization, trophic support, in vitro culture, rates of development.