Phylogenetic relationships between cultivated and wild species of the genus Beta revealed by DNA "fingerprinting"

Forty-one accessions of the genus Beta representing wild and cultivated species of all sections were analyzed by DNA "fingerprinting". Four sugar beet minisatellite DNA probes revealed characteristic banding patterns with Southern-hybridized Beta DNA restricted with HindIII. A total of 111 polymorphic RFLP bands were scored across all accessions. Cluster analysis based on genetic similarity estimates for all 820 combinations of accessions revealed the following results. (1) All accessions could unambiguously be identified by a characteristic RFLP banding pattern. (2) The sugar beet cultivars examined displayed a low level of genetic diversity; they showed high similarity to B. vulgaris ssp. maritima but low genetic similarity to the other wild species of section I. (3) In most cases, the present taxonomic classification of the genus Beta was confirmed. Species of sections II, III, and IV were clearly distinguishable from those of section I except for B. macrocarpa, which showed high similarity to wild species of section II. In a second experiment, 108 single-copy RFLP probes from sugar beet were Southern hybridized with B. procumbens DNA. A surprisingly low degree of homology (34%) was found. The results are discussed with regard to the taxonomic classification of the genus Beta.