Reversible Inhibition of Cell Division and Enlargement in Plant Tissues by 2,6-Diaminopurine. ∗

Summary

1. 2,6-diaminopurine has been shown to inhibit cell division in tobacco stem callus and habituated tobacco callus cultures, to prevent the formation of buds in tobacco stem pieces cultured in vitro, to reduce cell enlargement in tobacco pith pieces cultured in vitro, and to inhibit elongation of etiolated pea stem and Avena coleoptile segments floated on test solutions. 2. Adenine, arginine, guanine, hypoxanthine, and xanthine were tested in attempts to reverse the inhibition by diaminopurine of callus growth and bud formation in tobacco stem segments. Adenine was very effective and slight reversal was obtained with guanine and hypoxanthine. 3. Reversal of the DAP inhibition of tobacco pith cell enlargement was obtained with adenine and guanine, but adenine was more effective. No other compounds were tested on this tissue. 4. Reversal of the diaminopurine inhibition of etiolated pea stem segment elongation was attempted only with adenine, adenosine, and adenylic acid. All three compounds gave partial reversal.