Anatomy of shoot production in vitro from explants of cauliflower curd (Brassica oleracea L. var. botrytis subvar. cauliflora DC.)

Abstract

The cauliflower curd consislt of à main shoot from which many first-order branches develop in acropetal succession. Successive branching orders develop from the apices which exist on each branch and which form the surface of the marketable curd. The branches have the same anatomical structure as the majority of herbaceous dicotyledons. Explants taken from the surface of the marketable curd of cauliflower were cultured, in nutrient medium. Starting on the fifth day after inoculation of the explant in the nutrient medium, the anatomical modifications in the explant were observed. The parenchymatic cells adjacent to the vascular bundles of the peduncle divide periclinally and increase in volume. Apparently this phenomenon is related to the differentiation of vascular elements which occur in a disorganized fashion. Concomitantly there is a progressive and gradual differentiation of the apical regions from undifferentiated meristems to organized shoot meristems, producing leaf primordia in a regular fashion. In approximately 10% of the cultures, bracts which were present on the explant developed greatly when in contact with medium, and shoots were formed from their blades.