Tracheogenesis in callus tissue of Plantago asiatica L.

Xylogenesis was observed in the morphogenic and nonmorphogenic calluses. The light microscopy was used for a histological study. The ultrastructure of the calluses was analysed using the JEM 100 B transmission electron microscope. Tracheary elements were formed in all studied kinds of calluses. They had lignified spiral or reticulate thickening of cell walls. In nonmorphogenic calluses, tracheary elements were chaotically dispersed. In morphogenic callus, the vessel system during caulo- and rhizogenesis from tracheary elements was formed. The application of TEM allowed for an observation of the very early stages of formation of tracheary elements which were initiated by the degeneration of cell protoplast and transformation of cell wall. Tracheogenesis has been already studied in callus culture. However, rarely the authors were concerned on the phenomenon of the ultrastructure level.