Development of polymorphic microsatellite markers for sugar beet (Beta vulgaris L.)

A total of 2884 Expressed Sequence Tags (EST) and genomic sequence of FLC-Like gene, a major gene controlling the flowering time in sugar beet, were extracted from NCBI database. After sequence alignment and construction of unrepeated primers, all contigs were surveyed for identification of 2-6 bp SSRs. Then, specific primers were designed from the conserved regions around the SSRs. Three hundred consensus sequences (14% of all EST sequences) contained SSRs with an average of 4.6 kb of expressed region of genome for one SSR. Trinucleotide repeats were the most frequent (36.33%) SSRs. Among the 15 specific primer pairs tested with PCR on 12 beet accessions, cultivars, and lines, six polymorph markers were identified four of which were the sequences of the flowering genes. These markers were able to generate 2-4 alleles per locus with minimum and maximum polymorphic information content (PIC) of 0.4 and 0.66, respectively. This EST-SSRs dataset and new identified SSR markers may be used as important sources for genetic and taxonomic studies, molecular breeding and identification of sugar beet varieties in the future studies.