Adenosine Phosphate and Nicotinamide Adenine Dinucleotide Pool Sizes during Shoot Initiation in Tobacco Callus

Shoot-forming tobacco callus is found to have high levels of adenosine phosphates and NAD⁺, and a low energy charge during meristemoid and shoot primordium formation. NADH levels are low and show little change during this period. There is a decline in the content of NADPH to nondetectable levels during the process, and a transient increase of NADP⁺ is observed early in culture. These patterns are indicative of a shift to a more intensive rate of metabolism during meristemoid and shoot primordium formation and apparently reflect the requirement for energy and reducing power during organ initiation.