HISTOLOGICAL STUDY OF NODULE MORPHOGENESIS FROM CICHORIUM-INTYBUS L. LEAVES CULTIVATED IN-VITRO

Chicory root, stem, and leaf tissues have the propensity to regenerate organogenetic nodules following a wounding treatment. Using histologi cal methods, we described this phenomenon on leaves of Cichorium intyb us L. cv. 'Witloof' cultivated in vitro. Nodule morphogenesis and bud regeneration from nodules were characterized with the assistance of li ght and transmission microscopy techniques. Semithin and ultrathin sec tions of leaves and nodules were prepared from nodule induction to bud regeneration phases. Starch and inulin in differentiating tissues wer e histochemically detected in semithin and handmade sections. Our stud y demonstrates that nodules are formed in direct contact with Vascular bundles of the leaves. The nodules consist of organized structures: a vascular center is surrounded by a large parenchyma, which is delimit ed by a periderm of multiple cork cell layers. Inside the vascular cen ter near phloem tissues, a secretory network of articulated pseudolati cifers develops. From parenchymatous cells, in the vicinity of vascula r centers, endogenous buds can be induced. In this region, several cor ds of vessel initials formed the vascular connection between neoformed buds and vascular centers. Simultaneously, transfer cell specializati on occurs near the neoformed vascular strands. Vascular centers play a major role in this kind of organogenesis. Sugar metabolism appears to be closely related to nodule morphogenetic events.