Identification of standard type cultivars in Chrysanthemum (Dendranthema grandiflorum) using SSR markers

Chrysanthemum has several hundreds of commercialized cultivars with similar morphological characters including flower color and type. Correct labelling of the cultivars and protecting the intellectual property rights of the breeder requires an accurate and reliable method to discriminate the cultivars. Simple sequence repeat (SSR) markers were used to identify and discriminate the standard type cultivars in chrysanthemum. 23 SSR markers from the chrysanthemum SSR database were used to identify eleven standard type chrysanthemum cultivars. Of the 23 SSRs, 7 markers showed polymorphic fragments. A total of 187 alleles were obtained using 7 SSR markers in 11 cultivars. The number of alleles per locus ranged from two to four with an average of 2.7 per locus. The polymorphism information content (PIC) of 7 SSRs ranged from 0.25 to 0.60 with an average of 0.41. Genetic relationship by cluster analysis based on unweighted pair group method with arithmetic mean (UPGMA) method revealed a genetic distance of 0.25-1.00 among the 11 cultivars. The 11 standard type cultivars were discriminated by the ChSSR_16 marker alone. However, two cultivars (Sei_no_issei and Makoto) showed complete genetic similarity and could not be distinguished. Hence, the results showed that these SSR markers may prove useful in identifying additional chrysanthemum cultivar types and to assess genetic relationships among cultivars.