A Comparative Genetic Diversity Analysis of Big-bracted Dogwoods

The big-bracted dogwoods (Cornus sp.) are a group of popular woody ornamental trees. There are hundreds of named cultivars spanning C. florida, C. kousa, and C. nuttallii, as well as interspecific hybrids between the three. Rutgers University has had an active dogwood breeding program for over 40 years, releasing 14 cultivars, and is home to a large germplasm collection holding many advanced-generation, interspecific hybrids. The purpose of this study was to analyze the genetic diversity and relationships of 100 commonly available cultivars and 230 interspecific hybrid breeding selections held in the Rutgers germplasm collection in addition to confirming pedigree records and identifying possible male parents of seedlings derived from open pollination. Twenty simple sequence repeat markers were amplified and used to fingerprint each accession. Peaks were scored using GeneMapper v5. The data obtained were inputted into the cluster analysis program NTSYSpc to generate a UPGMA dendrogram that depicts the relationships between samples. A Bayesian population analysis was also obtained. A discussion of the results, including implications for future dogwood breeding efforts, will be presented.