Conditions for strict autotrophic culture of tobacco callus.

Organic gelling agents such as agar and agarose provide a heterotrophic substrate for growth of illuminated tobacco callus. When green cells are incubated in CO(2)-free air on a medium lacking sucrose but solidified with 1% agar, an increase in relative dry weight is sustained through two passages. Similar results with different inoculum sources, and with three brands of agar and two forms of agarose, suggest this is a general phenomenon. A fully autotrophic culture system was developed employing polyurethane pads to support cells in a liquid medium lacking sucrose. Growth was negligible in two passages in CO(2)-free air, and increased with each added increment in CO(2) concentration.