Development and incorporation of microsatellite markers into the linkage map of sugar beet (Beta vulgaris spp.)

A set of informative simple sequence repeat markers has been identified for use in the marker-assisted breeding of Beta vulgaris. Highly enriched smal l insert genomic libraries were constructed, consisting of 1536 clones (wit h inserts of between 250-900 bp). Screening the clones with CA, CT, CAA, CA TA and CATA nucleotide-repeat probes revealed positive hybridisation to ove r 50% of the clones. Of these 340 were sequenced. Primer pairs were designe d for sequences flanking the repeats and, of these, 57 pails revealed lengt h polymorphism with 12 Bern accessions. Heterozygosity levels of the SSR lo ci ranged from 0.069 to 0.809. Heterozygosity levels were found to be simil ar to those detected employing RFLP probes with the same accessions. Phenet ic analysis using the markers, indicated relationships in accordance with k nown pedigrees. Twenty three of the SSR markers were polymorphic in one or both of two F-2 mapping populations, and were placed relative to a framewor k of RFLP probes. The markers are distributed over all nine linkage groups of sugar beet.