SSR markers are:
Simple sequence repeats or microsatellites consist of tandem repeats of 1-6 bp motifs such as ATATAT or CAG repeats, abundant and evenly distributed across eukaryotic genomes. Variation in repeat number creates high polymorphism due to slippage during DNA replication by DNA polymerase. Primers flanking repeat amplify locus via PCR, and alleles differ in fragment length detectable by gel electrophoresis or capillary sequencing with fluorescent labels. Because both alleles at locus amplify and can be visualized simultaneously, SSR distinguishes homozygous from heterozygous state: single band for
Ref: Tautz D. Hypervariability of microsatellites; McCouch et al. 1997 Microsatellite markers in rice – co-dominant nature