14C-metabolism during callus induction in tobacco

Abstract

Tobacco pith-phloem explants and callus were incubated in 14C-glucose, 14C-acetate or 14C-bicarbonate on different days in culture in the dark. 14CO2 production and 14C incorporation into ethanol-insoluble components were generally greater in the subcultured callus than in the pith-phloem explants during days 0 to 5 in culture. Greatest radioactivity from all substrates was in the ethanol-soluble portion, which was further fractionated into lipids, amino acids, sugars and organic acids. Although incorporation into the different fractions varied with the substrate, the patterns of labelling were relatively similar in the two tissues. The greater wound metabolism in the subcultured callus in comparison to the pith-phloem explant during the induction phase of callus formation was correlated with the earlier visible initiation of cell proliferation in the subcultured tissue.