Diversity Analysis of Forty-one Tree Peony Cultivars by EST-SSR Markers

Tree peony and related industries make up quite a large proportion in tourism income of Luoyang, China. Short flowering feature of most native tree peony cultivars is a key restrictive factor of economic benefits increasing. Hybridizing native superior cultivars with late-flowering introduced cultivars would be a fundamental way to overcome short flowering problem. In order to provide basis for parent selection for late-flowering breeding, twenty novel polymorphic EST-SSR markers were developed and used to evaluate diversity of forty-one tree peony cultivars (including twenty-one native cultivars, nineteen Japanese cultivars and one American cultivar). The observed number of alleles per locus ranged from 2 to 10, on average 4.3 alleles per locus and the effective number of alleles per locus ranged from 1.045 to 4.661, on average 2.466 alleles per locus. The expected (He) and observed (Ho) heterozygosity at each locus ranged from 0.044 to 0.795 and 0 to 0.857, respectively, on average 0.509 and 0.258 per locus. UPGMA analysis revealed that the forty-one tree peony cultivars could be grouped into seven clusters. Native cultivars formed two clusters (Ⅰand Ⅲ) except “Luoyanghong” which formed a separate cluster (Ⅶ). Japanese cultivars scattered into four clusters, most of which were grouped into cluster (Ⅱ), the remaining four cultivars, “Togawakan” and “Kanzakura Jishi” were grouped into clusterⅠ, “Okina Jishi” and“Shin Shichifukujin” formed two separate clusters respectively (Ⅳ and Ⅵ). The only American cultivar “High Noon” formed a separate cluster (Ⅴ).