Use of Chicory Root Explants In Vitro as a Model for the Induction of Different Stem Types

Summary Chicory ( Cichorium intybus L. var. foliosum Hegi) root explants were cultured in vitro under various photoperiodic regimes. Four specific stem types were detected. Under long-day conditions, flowering-stems with side branches, green expanded leaves and flower buds were initiated. Under complete darkness, white etiolated stems without expanded leaves and without flower buds were observed. When cultures were transferred from darkness to long-day conditions after at least 10 days, white etiolated stems with green expanded leaves on top were obtained. Daily application of far-red light on dark cultures led to the initiation of white stems with expanded white leaves. A fifth stem type, a green stem with expanded leaves and without flower buds, was discerned following application of gibberellin A on vegetative shoot tips initiated on chicory root explants in vitro , cultured under short days. The use of this model for further study of stem and flower induction in chicory, on the physiological as well as on the molecular biological level, is discussed.