No abstract

Five isozyme systems were genetically investigated. The different separation techniques, the developmental expression and the use as marker system in sugar beet genetics and breeding is discussed. Isocitrate dehydrogenase was controlled by two genes. The gene products form inter- as well as intralocus dimers, even with the gene products of the Icd gene in B. procumbens and B. patellaris. Adenylate kinase was controlled by one gene. Three different allelic forms were detected, which were active as monomeric proteins. Glucose phosphate isomerase showed two zones of activity. One zone was polymorphic. Three allelic variants, active as dimers, were found. Phosphoglucomutase also showed two major zones of activity. One zone was polymorphic and coded for monomeric enzymes. Two allelic forms were found in the accessions studied. The cathodal peroxidase system was controlled by two independent genes, of which only one was polymorphic. The gene products are active as monomers. Linkage was found between red hypocotyl color (R) and Icd 2. Pgm 1, Gpi 2, Ak 1 and the Icd 2-R linkage group segregated independently.

A systematic procedure is described to obtain habituated cell suspensions from different explant sources of sugarbeet (Beta vulgaris L.).Cytokinin habituation occurred spontaneously. Auxin habituation could be induced by successive lowering of the external hormone concentration. Habituation was reversible and independent of the cell type or explant source. The habituated nature of the cells was lost during regeneration and had to be reinduced by adequate treatments.A method for initiating habituated self-regenerating lines was established. These cultures were less stable. Total dedifferentiation caused the loss of the regeneration capacity. Reculturing of the regenerated plants did not result in a higher percentage of primary regeneration.

Different methods of classification, based on total protein patterns as well as on specific isoenzyme patterns, were compared in order to establish an identification system for sugar beet varieties and lines. Single seed patterns and bulk extractions of total and fractionated proteins were compared on SDS-PAGE. Due to important intra-populational variation contrasting with similarity at the varietal level no method proved to be sufficiently discriminatory. Twelve sugar beet lines have been genotypically fingerprinted on the basis of five allozyme systems. The allele frequencies of each variety have been measured by using 60-100 individuals. From the data, genetic distance coefficients have been calculated in order to group the different entries by cluster analysis. In addition, a comparison has been made between two seed lots independently obtained from the same parental lines, to test the stability over years. Seeds from the same parental lines, but produced in different localities (Denmark, Italia and USA), were compared to test the influence of the environment on the classification. It has been concluded that isozymes could provide a useful tool for cultivar distinction. The variability at the level of allele frequencies within localities was small. The stability of different generations of the strains was relatively constant. Different strains originating from the same seed firm were less distinct than strains originating from different seed firms.

Eleven isozyme systems were used to identify the extra chromosomes, originating from Beta procumbens, in progenies of 33 monosomic additions in beet (B. vulgaris). Nine groups of monosomic additions could be distinguished, representing the nine different chromosome types of B. procumbens.