Analysis of Genetic Diversity and Identity of Redbud (Cercis) Cultivars Using SSR Markers

Redbud (Cercis spp.) are popular ornamental small trees or shrubs, valued commercially for their showy early spring bloom, heart-shaped glossy leaves, and adaptability to diverse environmental conditions. The genus Cercis (Fabaceae) contains seven to thirteen species or sub-species that occur in North America, Europe, and Asia. Species range in size from small shrubs to trees, tolerate full sun to shade, and are hardy in USDA Zones 4-9. At least 12 cultivars of redbud have been introduced in the past decade with variations in foliage characteristics, flower color, or plant habit. We developed SSR markers for C. canadensis and other species and used them to analyze 20 cultivars. We also tested the inheritance of these markers by analyzing parents and progeny from controlled hybridizations. These markers successfully differentiated among all the cultivars tested, and were useful in estimating genetic distances between cultivars. We are currently investigating the relationship between genetic associations revealed by SSR markers and various horticultural and adaptability traits in the landscape.