Syumka A. 3. Intraspecific changeability of Cercospora beticola Sacc. and improvement of methods for evaluation of sugar beet resistance to Cercospora leaf spot disease

Object - intraspecific changeability of Cercospora beticola fungi. Purpose - investigation of the Cercospora beticola Sacc. intraspecific changeability and improvement of methods for evaluation of sugar beet resistance to Cercospora leaf spot disease in the field and in vitro culture. Methods - microscopically; biotechnological; biochemical; molecular-genetic; mycological; phytopathological; statistic. Novelty - A collection from 32 isolates of Cercospora leaf spot disease agent, selected from the different areas of Ukraine and Russia has been created. It was found the considerable changeability of cultural characteristics and cercosporin content of isolates, which does not depend on the geographical origin of isolates. Molecular-genetic studies did not show association between the groups of isolates that was based on cercosporin content and their phylogenetic relationship. The methods for determination of catalase, peroxidase and polyphenoloxidase activity were improved. It was established the features of changing of enzyme activity in sugar beet tissues in the in vitro culture at the action of C. beticola cultural metabolites. The effective method for introduction into the in vitro culture explants from the seed of representatives of genus Beta L. was proposed. The method for creation of infectious background of the agent of Cercospora leaf spot disease using isolates culture of the fungus C. beticola have been improved, that allowed to investigate their virulence and influence the indexes of sugar beets resistance. It was shown the presence of antagonistic relations between populations of C. beticola and their separate isolates.Research results - are used in the practical work and educational process. Area - plant pathology.