Cytoplasmic diversity in leaf beet cultivars as revealed by mitochondrial DNA analysis.

Mitochondrial (mt) DNA restriction fragment length polymorphisms are convenient markers for identifying cytoplasmic variation among plant cultivars. In an attempt to detect new cytoplasmic genotypes useful for sugarbeet breeding, we have compared the hybridization patterns of mtDNA from three groups of cultivated beets, viz. leaf beet, garden beet, and fodder beet. Utilized as probes were the two sugarbeet mtDNA clones that were capable of distinguishing normal fertile and different sources of male-sterile cytoplasms from one another. The analysis allowed the identification of four chondriome types among 14 leaf beet cultivars examined. Two out of the four chondriome types were found to be different from the previously described fertile or male-sterile chondriome type. Our results thus indicate that leaf beet cultivars and landraces make up the primary cytoplasmic gene pool of the sugarbeet.