Phylogenetic relationships between cultivated and wild species of the genusBeta revealed by DNA ?fingerprinting?

Abstract

Forty-one accessions of the genusBeta 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-hybridizedBeta DNA restricted withHindIII. 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 toB. 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 genusBeta was confirmed. Species of sections II, III, and IV were clearly distinguishable from those of section I except forB. 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 withB. procumbens DNA. A surprisingly low degree of homology (34%) was found. The results are discussed with regard to the taxonomic classification of the genusBeta.

Evaluation of rhizomania-resistance segregating sequences and overall genetic diversity pattern among selected accessions of Beta and Patellifolia. Potential implications of breeding for genetic bottlenecks in terms of rhizomania resistance

“…These results are also in agreement with the observations made by Jung et al (1993), according to which sugar beet cultivars manifest low values of genetic diversity and a close relationship to B. vulgaris ssp. maritima, but rather low genetic similarity to other wild species (Jung et al 1993).…”

“…Besides, we confirm here that a considerable part of biodiversity may still be exploited from the sections Beta and especially Corollinae with the latter constituting most probably the driving force of ongoing speciation, as it was previously reported (Kubis et al 1997). These results are also in agreement with the observations made by Jung et al (1993), according to which sugar beet cultivars manifest low values of genetic diversity and a close relationship to B. vulgaris ssp. maritima, but rather low genetic similarity to other wild species (Jung et al 1993).…”

“…The uttermost importance of this application for variety registration was previously raised (Jung et al 1993;Smulders et al 2010). We confirmed also a general tendency observed by Smulders et al (2010), according to which diploid cultivars display greater genetic distances and higher levels of genetic differentiation than triploids due to a higher probability of allelic repetitions in the latter (Smulders et al 2010).…”

“…Although B. macrorhiza and B. corolliflora are generally regarded to represent separate forms/species, it seems at the same time that the borders between individuals belonging to this section may in fact be less clearly delineated and much more difficult to recognize than for any other exotic germplasm combination tested in our study. As proved by molecular methods, such a close relationship between these species was reported earlier (Jung et al 1993). Some accessions belonging to these species cluster with each other and as a consequence may be easily misclassified (Reamon-Büttner et al 1996).…”

“…Being restricted in their distribution pattern to the regions of Canary Islands, Madeira and Southern Iberian coast, Patellifolia display actually a closer relationship with the representatives of other genera grouping to Hablitzieae, therefore their classification into the Beta-independent taxonomic unit has been suggested (Scott et al 1977;Jung et al 1993;Kubis et al 1997;Kadereit et al 2006). The lowest frequency of polymorphisms found for P. patellaris may be explained by the fact that this is a self-fertile tetraploid form.…”