3.3. Development of SSR markers
Based on the identified SSRs, we designed primer pairs using the Primer3 program (Koressaar and Remm, 2007). We
selected primer pairs for the di-nucleotide and tri-nucleotide repeat types, which were frequently used for SSR markers
according to previous studies. A total of 46 primer pairs were tested for their amplicon size and quality using 50 different
chrysanthemum cultivars by PCR. In the case of primer pairs that did not amplify any fragments, gradient PCR was performed
to identify an optimal annealing temperature. Primer pairs amplifying at least one fragment were further selected. A total of
16 out of 46 primer pairs showed several polymorphisms with reliable PCR amplicons using genomic DNA from 50 tested
chrysanthemum cultivars (Table 4). The number of alleles per locus varied from 1 to 15, with an average of 6.25 alleles. In
particular, the CM04 and CM05 markers showed 15 alleles, whereas CM16 exhibited only one allele. The expected hetero-
zygosity (He) ranged from 0 to 0.8958, and the polymorphism information content (PIC) ranged from 0 to 0.8872.