The Absence of Malvidin-3-Glucoside in Petiole Tissue Predicts Rare Red-Type Flower of Eastern Redbud ( Cercis canadensis L.)

Eastern redbud, Cercis canadensis L., is a popular ornamental tree in the U.S. and has flower colors of purple-type, red-type, and white-type. Most redbuds cultivars have purple-type flowers. Red-types and white-types are much less common. These unusual flower colors have become an important trait for incorporation into novel redbud cultivars. Eastern redbud seedlings require 3–5 years before blooming, making flower color selection a slow and expensive process. The ability to select seedlings for flower color type would significantly increase the efficiency of the breeding process. Redbud flower color is dominated by anthocyanin content; leaf petioles often show visible pink to purple color, indicating the potential presence of anthocyanin. In this study, anthocyanin profiles of 14 cultivars and 25 progenies of ‘Appalachian Red’ (red-type) × ‘Oklahoma’ (purple-type) were determined using HPLC. The petiole anthocyanin profiles were strongly indicative of plant flower-color types. Both peonidin-3-glucoside and malvidin-3-glucoside were dominant in petioles from all purple-type plants. In contrast, malvidin-3-glucoside was absent from petioles of red-type plants, and neither peonidin-3-glucoside nor malvidin-3-glucoside was detected among white-type cultivars. These results indicate that the presence or absence of peonidin-3-glucoside and malvidin-3-glucoside in petioles can be a physiological marker for identifying redbud flower color types.