RFLP markers in the genus Beta: characterization of DNA sequences from a Beta vulgaris library

Abstract

DNA sequences from a sugar beet genomic library were tested for their ability to crosshybridize and detect RFLPs in 40 accessions representing 13 different species and subspecies. A set of 32 sugar beet DNA sequences was categorized as either single copy non-polymorphic (SCN), single copy polymorphic (SCP), low copy repeated (LCR), or high copy repeated (HCR). The crosshybridization of these DNA sequences was analyzed at two different stringencies. At medium stringency, 12 of the DNA sequences hybridized exclusively to accessions from the section Beta, whereas 16 also crosshybridized to accessions from the section Procumbentes. Accessions from the related genus Atriplex showed crosshybridization for 13 of the DNA sequences. At low stringency, 94% of the sugar beet SCP sequences crosshybridized to the Procumbentes accessions, indicating that most of these sequences will crosshybridize with the majority of the species in the genus Beta. High levels of polymorphisms among the wild beets from the section Beta indicate that marker-guided backcross programmes are feasible using sugar beet genomic clones. The sugar beet DNA sequences also detected a considerable amount of RFLP variation among the Procumbentes and Atriplex accessions. This reflects the general usefulness of these markers in comparative genome mapping projects within the genus Beta. In another experiment, 87 clones were used in Northern hybridizations to estimate the proportion of transcribed sequences present in the genomic library. In total, 17 clones detected transcripts.