Flowering dogwood is an important tree of forests and urban landscapes in the eastern United States. This native tree blooms early in the spring as new leaves unfold. The inflorescence consists of petallike subtending bracts of red, pink, or white surrounding a cluster of 20 or more tiny true flowers that are yellow or white (Witte et al., 2000). Dogwood is an attractive tree in all seasons and has become a widely used landscape tree. Although flowering dogwood is a native tree and many wild trees exist, the popularity of this tree has led to the development of many cultivars. New cultivars are either developed from mutations or sports of other cultivars, or from the selection of wild dogwood trees for various horticultural traits (Witte et al., 2000). Cultivated lines of dogwoods are propagated from axillary buds, which are grafted onto rootstocks that are produced from wild (native) seed collections (Dirr, 1998). This propagation technique produces cultivars or lines of purportedly identical trees with specific, desirable phenotypic traits. Cultivated selections have been developed for large bracts; double bracts; red, pink, or white bracts; variegated leaves; various growth habits; and disease resistance. There are currently more than 80 cultivars of flowering dogwood (Witte et al., 2000) and many are described and illustrated in Cappiello and Shadow (2005). Because many cultivars are very similar in appearance, there is a need for a method of identification that is based on genotype rather than solely on phenotypic characteristics.
Molecular markers can be very useful in cultivar identification or in determination of parentage of sexually propagated species. This is particularly important for proprietary plants, because molecular markers can be used in patent applications and subsequently for protection of the patented cultivars against infringement (Saunders et al., 2001; Weising et al., 1995). Currently, one of the most popular DNA fingerprinting techniques is amplified fragment length polymorphism (AFLP) (Vos et al., 1995). Amplified fragment length polymorphisms are widely used because they can be generated without prior knowledge of an organism's genome and are generally reproducible within and between laboratories (Amador et al., 2001; Saunders et al., 2001; Savelkoul et al., 1999; Vos and Kuiper, 1997).
In this study, AFLPs were generated to assess the genetic variability between selected cultivars and lines of Cornus florida and to construct a dichotomous key using specific molecular markers to distinguish some of the more popular cultivars and breeding lines from one another.
Amador, D.M., Brazeau, D., Farmerie, B., Blake, A., Clark, G. & Whitten, M. 2001 Amplified fragment length polymorphisms (AFLP) workshop Interdisciplinary Center for Biotechnology Research. University of Florida, Gainesville, Fla
Belaj, A., Rall, L., Trujillo, I. & Baldoni, L. 2004 Using RAPD and AFLP markers to distinguish individuals obtained by clonal selection of ‘Arbequina’ and ‘Manzamilade Sevilla’ olive HortScience 39 1566 1570
DeRiek, J., Dendauw, J., Leus, L., DeLoose, M. & VanBockstaele, E. 2001 Variety protection by use of molecular markers: Some case studies on ornamentals Plant Biosystematics 135 107 113
Dirr, M.A. 1998 Manual of woody landscape plants: Their identification, ornamental characteristics, culture, propagation and uses 5th ed. Stipes Publications Champaign, Ill
Habera, L.H., Lamour, K.H., Donahoo, R. & Smith, N.R. 2004 A single primer strategy to fluorescently label selective AFLP reactions Biotechniques 37 902 904
Parks, E.J. & Moyer, J.W. 2004 Evaluation of AFLP in poinsettia: Polymorphism selection, analysis and cultivar identification J. Amer. Soc. Hort. Sci. 129 863 869
Saunders, J.A., Mischke, S. & Hemeida, A.A. 2001 The use of AFLP techniques for DNA fingerprinting in plants. CEQ 2000XL application information Beckman Coulter, Inc Fullerton, Calif
Savelkoul, P.H.M., Aarts, H.J.M., deHaas, J., Dijkshoorn, L., Duim, B., Otsen, M., Rademaker, J.L.W., Shouls, L. & Lenstra, J.A. 1999 Amplified fragment length polymorphism analysis: The state of an art J. Clin. Microbiol. 37 3083 3091
Trigiano, R.N., Ament, M.H. & Windham, M.T. 2003 DNA fingerprints nail the clones: How genetic mapping technology is revealing many cultivars’ true colors. Nursery Manage Production 19 43 46
Trigiano, R.N., Ament, M.H., Windham, M.T. & Moulton, J.K. 2004 Genetic profiling of red-bracted Cornus kousa cultivars indicates significant cultivar synonymy HortScience 39 489 492
Trigiano, R.N. & Caetano–Anollés, G. 1998 Laboratory exercises on DNA amplification fingerprinting for evaluating the molecular diversity of horticultural species HortTechnology 8 413 423
Vos, P., Hogers, R., Bleeker, M., Reijans, M., van de Lee, T., Hornes, M., Frijters, A., Pot, J., Peleman, J., Kuiper, M. & Zabeau, M. 1995 AFLP: A new technique for DNA fingerprinting Nucl. Acids Res. 23 4407 4414
Witte, W.T., Windham, M.T., Windham, A.S., Hale, F.A., Fare, D.C. & Clatterbuck, W.K. 2000 PB1670: Dogwoods for American gardens University of Tennessee Agriculture Extension Service Knoxville, Tenn