Three Routes to Orange Petal Color via Carotenoid Components in 9 Compositae Species

Abstract

We analyzed the petals of orange- and yellow-flowered cultivars of 9 Compositae (Asteraceae) species for total anthocyanin content, total carotenoid content, and carotenoid composition to clarify the mechanisms responsible for the differences in color. Petals of both orange- and yellow-flowered cultivars of these species contained yellowish carotenoids in common. There were three different ways for orange-flowered cultivars to add redness to the yellow base in order to form orange petals. The first way to display orange is to accumulate more anthocyanins than yellow-flowered cultivars; orange petals of Chrysanthemum morifolium, Gerbera jamesonii, and Zinnia elegans are mainly formed in this way. The second is to accumulate more carotenoids than yellow-flowered cultivars; orange petals of Helianthus annuus, Tagetes erecta, and Tagetes petula are formed in this way. The third is to accumulate more reddish carotenois than yellow-flowered cultivars; orange petals of Calendula officinalis, Gazania spp., and Osteospermum ecklonis are mainly formed in this way. These three ways could be combined through inbreeding to produce orange flowers that vary in color tones.