Chromosome morphology in a homozygous line of sugar beet

Abstract

The karyotype of a homozygous line of sugar beet (Beta vulgaris L.) was studied employing root tips that had been pretreated in 0.002 mol oxyquinoline, fixed in acetic alcohol (1:3), and squashed in lacto-propionic orcein. Chromosome measurements were made from photomicrographs. The average chromosome length was 2.46 μ, with a difference of 0.89 μ between the longest and the shortest chromosome. Seven of the nine chromosomes, including the nucleolar chromosome, have centromeres with a more or less median position. The two remaining chromosomes have submedian centromeres. Except for the satellite of the nucleolar chromosome, the technique employed did not reveal any differentiation in the arms of value for identifying the chromosomes. Because of the risk for reversal errors, the idiogram constructed must be viewed as an “apparent idiogram”.