Relevance. It was to study the variability of the degree of defeat of promising varieties of table carrots by diseases of various etiologies during storage for several years, to determine the level of their polymorphism based on resistance to various types of pathogens and the effectiveness of selection based on an individual immunological assessment of uterine root crops.Materials and methods. The experimental part of the work was performed in 2017-2020 at the FSBSI "Federal Scientific Vegetable Center" with carrot varietal populations of Margosha and Minor. The identification of the species composition of pathogens, the degree of damage, and the level of resistance of variety specimens were carried out in accordance with appropriate methods and determinants. For the immunological assessment of the resistance of carrot cultivars in vitro, the most virulent isolates of different types of fungi were used from the collection of the Laboratory of Immunity and Plant Protection of the Federal Center for Scientific Research.Results. It was established that in the populations of Margosha and Minor under natural storage conditions, the ratio and degree of spread of economically significant diseases differ significantly in different years. Based on an in vitro immunological assessment, a high polymorphism of the individual resistance of genotypes within both populations to the majority of micromycetes was revealed and the most resistant forms to the most dangerous types of pathogens were identified. Immunological analysis of the resulting offspring confirmed the high efficiency of group selection based on a comprehensive assessment of the stability of individual uterine root crops in vivo and in vitro.

It is important to reveal the genetic base of breeding genetic material used for development of new breeding accessions among diverse Brassica oleracea L. (CC, 2n = 18). Traditional varieties, hybrids and new ones recently developed are the main genetic resources.Classification of a collection with DNA markers enables to reveal valuable genotypes and establish the breeding accession pedigree that allows developing the new accessions with sustainable economically valuable traits. The use of microsatellite markers (SSR) in B.oleracea L. has shown high efficiency in discovering genetic polymorphism between varieties and within varieties as well. In this study, 16 primer pairs have been taken to amplify microsatellite loci of genomic DNA in national 24 breeding accessions of cabbage. On the basis of the data obtained the dendrogram has been constructed with use of Jaccard’s coefficient. All locistudied were high informative, where 14 out of 16 had a PIC > 0.5. As a result, the level of genetic polymorphism has reached 85.7%. The large cluster of head cabbages consists of three subclusters: mid-maturing and early-maturing accessions of white head cabbage, red head and savoy cabbages, late-maturing and midmaturing accessions of white head cabbage, respectively. Maximum genetic distance in the cluster of head cabbages was obtained between head cabbage ‘Slava 231’ and ‘Vertu 1340’ with genetic similarity 44.7%. The two varieties of red head cabbage ‘Gako 741’ and ‘Kamennaya Golovka 447’ were genetically similar at 71.1%. The relatively low genetic similarity of these varieties can be explained by that they belong to different varietal groups. The most genetically closest varieties were ‘Zimovka 1474’ and ‘Podarok‘ with genetic similarity 86,5%. Information on topologic differentiation obtained from cluster analysis can be the basis for selection of genetically valuable breeding material with the use of DNA markers (Marker Assisted Selection).

The potato is one of the main strategic crops in the Russian Federation, Belarus and Kazakhstan. Currently, we have achieved significant advances in the understanding of metabolic mechanism of carbohydrate and interconversion «sucrose – starch» in potato tubers. Sucrose synthase (Sus) is a key enzyme in the breakdown of sucrose. Sucrose synthase (Sus) is catalyzing a reversible reaction of conversion sucrose and UDP into fructose and UDP-glucose. The identification and subsequent characterization of the genes encoding plant sucrose synthase is the first step towards understanding their physiological roles and metabolic mechanism involved in carbohydrate accumulation in potato tubers. In the present work the nucleotide and amino acid polymorphism of the Sus4 gene fragments containing sequences of the sucrose synthase domain were analyzed. Sus4 gene fragments (intron III – exon VI) in 9 potato cultivars of Russian, Kazakh and Belarusian breeding were analyzed. The polymorphism of the Sus4 sucrose synthase domain sequences was first examined. The length of analyzed fragment varied from 977 b.p. (cultivars Favorit, Karasaiskii, Miras) to 1013 b.p. (cultivars Zorochka, Manifest, Elisaveta, Bashkirskii). It was demonstrated that the examined sequences contained point mutations, as well as insertions and deletions. The common polymorphism level was 5.82%. It was shown that the examined sequences contained 58 SNPs and 4 indels. The most variable were introns IV (12.4%) and V (9.18%). The most variable was exon IV. 7 allelic variants were detected. 6 different amino acid sequences specific to different varieties were also identified.

The results of complex estimation of structure of variety population Amager 611, the genetic analysis by inbreeding (J1-J9) and RAPD-markers are shown. The role of 17 phenotype groups in the variety population was determined. The suggestions for agriculture and maintaining of cv. Amager 611 are proposed.