Submitted to: Journal of the American Society for Horticultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/19/2008
Publication Date: 11/30/2008
Citation: Phillip A. Wadl, Xinwang Wang, Andrew N. Trigiano, John A. Skinner, Mark T. Windham, Robert N. Trigiano, Timothy A. Rinehart, Sandra M. Reed, and Vincent R. Pantalone (2008) Molecular Identification Keys for Cultivars and Lines of Cornus florida and C. kousa Based on Simple Sequence Repeat Loci. J. Amer. Soc. Hort. Sci. 2008 133: 783-793. Interpretive Summary: Most woody plant cultivars including dogwoods are propagated vegetatively, and new cultivars are obtained from the following two principle sources: conventional breeding and selection of spontaneous or induced variations of existing cultivars. Molecular markers can reliably identify clones, breeding lines, hybrids and cultivars. Using molecular markers, analysis of the genetic constitution of plants can be determined at an early stage, enabling the plant breeder to decrease the time and cost required for selection. Molecular marker development has been almost exclusively limited to agronomic and forestry crops. Most ornamental molecular marker research has been directed towards cultivar identification. For dogwood, the use of molecular markers has been used primarily in hybrid and cultivar detection. In this study, SSRs were used to determine the genetic variation between 24 cultivars and breeding lines of C. florida and 22 selected cultivars of C. kousa. Additionally, a dichotomous molecular key was constructed from specific SSR loci to distinguish most of these popular cultivars and breeding lines of both species.
Technical Abstract: Flowering dogwood (Cornus florida L.) and kousa dogwood (C. kousa Hance.) are popular ornamental species commonly used in the horticultural industry. Both trees are valued for their beautiful floral display and four season appeal. Species specific microsatellite (SSRs: simple sequence repeats) loci were developed and used to genotype and assess genetic diversity of 24 flowering dogwood cultivars and breeding lines and 22 kousa dogwood cultivars. Genetic diversity, as determined by alleles sharing distances, was high in both species. Molecular dichotomous cultivar identification keys were developed for cultivars and breeding lines of each species using a few polymorphic SSRs loci (four C. florida and five C. kousa). Most of the flowering dogwood (18 of 24) and all kousa dogwood (22 of 22) accessions could be distinguished from each other using SSRs; those that could not were resolved using DNA amplification fingerprinting (DAF). The reliability of both keys was assessed using five anonymous cultivars for each dogwood species, which were correctly identified using the keys. The genetic information presented herein will be useful for identification and verification of cultivars for nurserymen and as molecular markers for breeders and researchers.