[Influence of light and medium on the plating efficiency of isolated cells from callus cultures of Nicotiana tabacum var. "Samsun"].

Light increases the plating efficiency of single cells isolated from green callus cultures of Nicotiana tabacum var. "Samsun" and plated in densities of less than 100 cells ml(-1) by more than 100%. At optimal light intensities plating efficiences between 80 and 90% were achieved with green cells, whereas the growth of isolated cells from chlorophyll free callus cultures was inhibited by light.Plated at low densities the isolated tobacco cells require the addition of kinetin and glutamine to a modified Murashige-Skoog-Medium for growth. The addition of these two substances is not necessary in the case of callus cultures or at higher plating densities (i.e. 500 or more cells ml(-1)). The requirement of kinetin for the growth of isolated cells can be met by the addition of small amounts of conditioned media from suspension cultures to the modified M+S-medium supplemented with glutamine, which demonstrates the production and release of a highly active cytokinine by the cells.