Induction of auxin-nonrequiring tobacco calluses and its reversal by treatments with auxins

Auxin-nonrequiring calluses were induced with high frequenciesby short treatments with auxins from auxin-requring ones. Auxin-requiringcalluses T22 and XD6S2, subcultured on a medium containing 1mg/liter IAA as plant growth regulator, required quite differenttreatment for induction from auxin-nonrequiring calluses; fromcalluses T22 and XD6S2, auxin-nonrequiring calluses were inducedby treatments with low concentrations of auxins (0.01–0.1mg/liter of IAA or NAA) and high concentrations of syntheticauxins (10–100 mg/liter of NAA or 1–10 mg/literof 2,4-D), respectively. No auxin-nonrequiring calluses wereobtained when they were transferred directly to the basal medium(hormone-free medium). The transformation of auxin-requiring into auxin-nonrequiringcalluses was fully reversible by treatment with 1 mg/liter ofIAA at an early stage of subculturing on the basal medium, butnot after prologed subculturing. ¹Part XXI in the series, ‘Studies on Plant Tissue Cultures’.Part XX, see Proceedings of the IVth International FermentationSymposium: Ferment. Technol. Today 697 (1972). (Received May 29, 1973; )