EFFECTS OF BA, TDZ, AND CPPU ON FORMATION OF ADVENTITIOUS SHOOTS FROMCALLUS DERIVED FROM APPLE COTYLEDON

Callus derived from cotyledons of 'Fuji' apple were cultured on 1/3 MS medium supplemented with various concentrations of BA and NAA. The ef fects of BA, TDZ, and CPPU at 1.0 to 8.0 mg . liter(-1) on shoot regen eration from calli and NAA on subcultured calli were investigated. 1. Cotyledons produced callus profusely when cultured on a medium supplem ented with 0 to 4.0 mg. liter(-1) BA and 0.5 to 10.0 mg . liter(-1) NA A. Callus formation occurred only at the proximal part of the cotyledo n exposed to 0 or 0.1 mg . liter(-1) NAA. However, calli formed from t he distal and middle regions at 0.5 mg . liter(-1) NAA or higher. 2. C allus morphology was dependent on concentrations of NAA and BA. With N AA alone, soft calli were produced, whereas at 0.5 to 4.0 mg . liter(- 1) BA and at combinations of 0 to 0.1 mg . liter(-1) NAA and 0.5 to 8. 0 mg . liter(-1) BA hairy calli were induced. Combinations of 10.0 mg. liter(-1) NAA and 2.0 to 10.0 mg . liter(-1) BA gave rise to globular calli. 3. When globular calli were cultured on the medium with 4.0 mg . liter(-1) CPPU and 0 NAA and then subcultured onto a fresh medium a t 2-week interval for 6 weeks, 60 % of the callus explants regenerated shoots; about 12 shoots per callus were obtained 12 weeks after begin ning the experiment. TDZ also produced a positive effect on shoot rege neration from callus, but the percentage of explants forming shoots an d the number of shoots formed were less than those treated with CPPU. The effect of BA on shoot formation from callus was comparatively weak . The addition of 0.1 mg. liter(-1) NAA to CPPU greatly reduced the nu mber of shoots regenerated.