In vitro induction of the formation of tracheary elements from suspension-cultured cells of the conifer Cryptomeria japonica

Key message We found tracheary elements that were induced in suspension cultures of cells derived from young needles of the conifer Cryptomeria japonica a fter cells had been transferred to solidified medium. The formation of tracheary elements was induced in suspension cultures of cells derived from young needles of the conifer Cryptomeria japonica , 7 days after the cells had been transferred to solidified medium. Before induction by the change in culture medium, suspension cultures contained no detected differentiated cell. The tracheary elements were characterized by helical, reticulate and/or pitted thickening of secondary walls. Induced tracheary elements were longer than surrounding non-differentiated cells. Before induction, cortical microtubules in a large number of suspension-cultured cells were predominantly oriented transversely with respect to the long axis of the cell. This induction system provides a useful model for studies of the differentiation of xylem cells of conifers in vitro.