Néoformation de Bourgeons Végétatifs et Inflorescentiels à Partir de Disques Foliaires du Crepis capillaris L. Wallr. cultivés in vitro

Abstract

Summary Foliar discs excised from plants of Crepis capillaris are remarkably able to regenerate buds when cultured in vitro on Murashige and Skoog's medium added with indole acetic acid (2 mg/l) and kinetin (1 or 5 mg/l). Dedifferentiation begins by the reactivation of the parenchyma located near the veins, at the vicinity of the excised margins of the explants. It leads to the establishment of a callus on which primary meristematic cells organise, from place to place, numerous shoot meristems. The vegetative or reproductive nature of the meristems depends upon the season of the excision. Foliar discs born of vegetative plants give rise only to vegetative buds. On the same medium, during summer, discs belonging to flowering plants put in place reproductive buds, directly or after a short vegetative phase. In both cases, the dedifferentiation is caracterised by a great nuclear stability and by the preservation of the diploid state pre-existent in the mother-plant. The retention of an induced floral condition in the foliar discs after their excision is also discussed.