Sugar beet is hypothesized to have a narrowed genetic base due to its origin as White Silesian Beet and from numerous breeding selections and practices. High sugar quality, yield of recoverable sugar, cytoplasmic-male sterility system, monogermity, pests and disease resistance and bolting resistance constitute some of the adaptations that significantly influenced the existing genetic background of the crop. In this study we aimed to evaluate the extent of genetic diversity existing in wild beet representatives of Beta and Patellifolia and sugar beet cultivars, with a special focus on the complex Beta vulgaris. Another purpose was to determine the potential usefulness and conformity of selected molecular markers in different groups of materials in the context of rhizomania resistance. To reach these goals, molecular RAPD, ISSR techniques, literatureselected rhizomania resistance-segregating sequences as well as mitochondrial markers were used. The comparison of genetic diversity in wild and cultivated Beta forms shows that the population differentiation values and distance values are relatively high in cultivars. Moreover, the diversity component seemed to be compromised rather on the level of population (Hs) than in total (Ht) in cultivars. Our results shed a new light on the expected genetic bottlenecks existing in cultivars and revealed features specific for individual taxa (Patellifolia, Corollinae). Some degree of distinctiveness was suggested between genetic determinants of rhizomania resistance in modern cultivars in comparison with wild resistance sources. In addition, we document here an internal heterogeneity existing in selected wild/weedy accessions at the level of crucial sequences using high resolution melting.

Search for genotypes resistant to Cercospora (Cercospora beticola Sacc.) in multigerm breeding materials of sugar beetPoszukiwanie genotypów odpornych na Cercospora beticola Sacc. w wielonasiennych materiałach hodowlanych buraka cukrowego Summary. In sugar beet cultivation, one of the main factors causing a significant drop in size and yield quality is the infection of plant leaves by the fungus Cercospora beticola Sacc. The main aim of the work was to identify inbred lines of sugar beet with genes of resistance to this pathogen. The research and selection works were carried out in multigerm breeding materials type 2xZN with a different degree of homozygosity. For the study, 36 genotypes of the S1 generation and 34 genotypes of the S2 generation were selected as well as 1 standard (Andante) variety with an increased level of fungal resistance. The sensitivity of materials to infection of C. beticola was assessed using a laboratory method (in vitro test). After twice selection a high stabilization of resistance was found within the examined progeny and a clear differentiation between the progeny of the S1 and S2 generation. The average number of spots on 10 leaf discs in the studied 9 progeny of S1 generation was from 10.50 to 31.04, and in 11 progeny of S2 generation from 6.30 to 28.49 using infection under optimal conditions for fungal growth. The wide range of variability that occurred in the tested materials made it possible to select 9 genotypes of the S1 generation and the 11 S2 generation with a high level of resistance to the C. beticola and high cultivation value.

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W niniejszym doniesieniu zostały zaprezentowane najważniejsze osiągnięcia w zakresie zagadnień badawczych realizowanych w Pracowni Cytogenetyki i Metodyki Hodowli, Zakładu Genetyki i Hodowli Roślin Korzeniowych Oddziału IHAR-PIB w Bydgoszczy. Obejmują one: produkcję podwojonych haploidów, ochronę zasobów genowych, ocenę i selekcję genotypów odpornych na grzyb Cercospora beticola Sacc. oraz identyfikację genotypów w kierunku tolerancji na stres suszy w materiałach hodowlanych buraka cukrowego (Beta vulgaris L.).