The purpose of the article is to analyze the scientific, organizational, and popularization activities of the prominent Ukrainian scientist, geneticist, breeder, teacher, academician of the Ukrainian Academy of Agricultural Sciences and the National Academy of Sciences of Ukraine Oleksii Sozinov (1930–2018) within the Ukrainian Society of Geneticists and Breeders named after M. I. Vavilov (hereinafter – USGB). The methodological basis of the study is based on the principles of historicism and objectivity, as well as the source study approach. General scientific and historical methods were used: biographical, problematic and chronological, systematic, analysis and synthesis. The use of the microhistorical approach and comparative historical analysis made it possible to reveal more deeply the scientific contribution of the scientist and his influence on the development of breeding science.

The main attention is paid to the period of his leadership of UTGiS as president (1976–1986) and his further participation as vice president and member of the Society. The key areas of scientific activity of the scientist are highlighted, in particular, the study of cereal genetics, the study of mechanisms of genetic control of cereal protein biosynthesis, as well as the development of new approaches to breeding and molecular biology in Ukraine.

Special emphasis is placed on the scientist's active participation in interdisciplinary and international scientific cooperation, as well as his efforts to preserve the scientific heritage of M. Vavilov in the context of the development of Ukrainian and world genetic science.

It has been found that O. Sozinov was actively engaged in popularization activities: he was an editor and a member of the editorial boards of a number of professional publications, in particular those related to the activities of the UTGiS. His own publications on topical issues of modern genetics, breeding, and evolution of plants and animals are also of great scientific and historical importance.

It is substantiated that the long-term scientific activity of O. Sozinov became the basis for the formation of strategic directions for the development of domestic breeding and genetics. It is proved that he occupies a prominent place in the history of biological science of the twentieth century, and his contribution significantly influenced the formation and development of genetics and breeding both in Ukraine and abroad.

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