Assessment of Genetic Diversity in the White-Colored Variants of Spray-Type Chrysanthemum Cultivars Using SSR Markers

Chrysanthemums represent the second most important cut flower after rose on the global commercial market. The phenomenal importance and global popularity of chrysanthemums have attracted breeders' attention, resulting in the release of vast numbers of cultivars. Identifying these cultivars is crucial to protecting breeders' intellectual property rights and improving the efficiency of breeding. Distinguishing chrysanthemum genotypes based on their morphological characteristics is challenging as they vary highly within this group, hence requiring the use of efficient molecular markers. In this study, we evaluated the genetic diversity of 57 spray-type chrysanthemum cultivars bearing white, ivory, and cream-colored flowers. A total of six loci were evaluated regarding their polymorphism efficiency across the tested cultivars. Allele numbers ranged from 2 to 6, with a mean of 3.5 alleles per locus. The average polymorphism information content (PIC) was 0.53 for six SSR markers. Cluster analysis of genetic relationships using the UPGMA method showed a genetic distance of 0.31 to 1.00, and the 57 white variants of chrysanthemum cultivars were characterized using the tested SSR markers. However, two sets of cultivars, namely, Pure Angel-Neba and Ladost-White wing, exhibited total genetic similarity and hence could not be discriminated. These results provide efficient SSR markers that can be used to identify chrysanthemum cultivars (and assess their genetic relationships) that cannot be discriminated based on phenotype.