[Genetic diversity analysis and fingerprints of Chrysanthemum × morifolium based on SSR molecular markers].

The present study aims to explore the genetic diversity of germplasm resources of × (hereinafter, ×) at the molecular level and to establish a fingerprint database of × varieties. We employed 12 pairs of primers with high levels of polymorphism, clear bands, and high degrees of reproducibility to analyze the SSR molecular markers and genetic diversity of 91 × materials and 14 chrysanthemum- related materials. With regard to constructing the fingerprints of the tested materials, we chose 9 pairs of core primers. The findings revealed that 12 primer pairs detected 104 alleles in 105 samples, ranging from 2 to 26. The average number of observed alleles () per site was 9.25. The average number of effective alleles () per site was 2.745 6, with its range being 1.276 0 to 4.742 5. Shannon genetic diversity index () values ranged between 0.513 3 and 2.239 9 (=1.209 0). Nei's gene diversity index () ranged between 0.216 3 and 0.789 1 (=0.578 0). The observed heterozygosity () ranged between 0.223 3 and 0.895 2 (=0.557 5). The expected heterozygosity () ranged between 0.217 4 and 0.793 3 (=0.580 8). The polymorphism information content (PIC) ranged between 0.211 5 and 0.774 0 (=0.532 9). The genetic similarity (GS) ranged between 0.228 5 and 1.000 0 (=0.608 3). Cluster analysis revealed that when the genetic distance (GD) equals to 0.30, the tested materials can be classified into 2 groups. When the GD equals to 0.27, the first group can be divided into 6 subgroups; accordingly, 105 tested materials can be divided into 7 subgroups. The cophenetic correlation test was carried out based on the cluster analysis, and the corresponding results showed that the cluster map correlated with the genetic similarity coefficient (r=0.952 73). According to the results of Structure population analysis, we obtained the optimal population number, with the true number of populations (K) being 3 and the population being divided concerning Q≥0.5. Three subgroups, i.e., Q1, Q2 and Q3, included 34, 33 and 28 germplasms, respectively, and the remaining 10 germplasms were identified as the mixed population. During the experiment, 9 pairs of core primers were screened among the total of 12 for a complete differentiation regarding 105 tested materials, and the fingerprints of 91 × materials and 14 chrysanthemum-related materials were further constructed. Overall, there were significant genetic differences and rich genetic diversity among × materials, which would shed light on the garden application and variety selection fields of ×. The fingerprint database of 105 × varieties and chrysanthemum-related species may provide technical support for future research regarding the identification and screening system of × varieties.