14C-Metabolism During Growth and Shoot Formation in Tobacco Callus Cultures

Tobacco callus grown under shoot-forming and non-shoot-forming conditions was incubated in ¹⁴C-glucose, ¹⁴C-acetate or ¹⁴C-bicarbonate on different days in culture. ¹⁴CO₂ production, and ¹⁴C incorporation into ethanol-soluble and ethanol-insoluble fractions was greater in shoot-forming than non-shoot-forming tissues. Greatest radioactivity from all substrates was in the ethanol-soluble portion, which was further fractionated into lipids, amino acids, sugars and organic acids. Greater conversion of ¹⁴C-glucose and ¹⁴C-acetate into these various fractions took place in shoot-forming than in the growing tissues, while the reverse was observed with ¹⁴C-bicarbonate. The differences in the metabolic patterns between shoot-forming and non-shoot-forming tobacco callus were in concert with the developmental behavior of the tissues.