Effect of Thidiazuron and Casamino Acid on Adventitious Shoot Formation from Roots of Apple prunifolia Borkh. MO-84) Plantlets Cultured In Vitro

Abstract

Effects of cytokinins (N⁶-benzyl amino purine : BAP, thidiazuron : TDZ) and casamino acid on adventitious shoot formation from the root of plantlets regenerated in vitro were investigated to establish an efficient regeneration system for apples through adventitious shoot formation. Shoot cultures of Mains prunifolia Borkh. var. ringo Asami strain MO-84 were grown on a Murashige-Skoog medium containing 1.0 mg liter^-1 BAP. Micropropagated plantlets were obtained at the end of 45 weeks of subculture on an MS medium containing 0.1 mg liter^-1 indole-3-butyric acid (IBA). Intact micropropagated plantlets were placed singly on the surface of the modified MS medium supplemented with various concentrations of BAP or TDZ, plus 0.1 mg liter IBA and 0.1 mg•liter^-1 GA₃ at 25°C under 3, 000 lx for 16 hours per day.
1. Optimum morphogenic response for adventitious shoot formation was obtained by using modified MS medium supplemented with 2.193.29 mg•liter^-1 TDZ, 0.1 mg•liter^-1 IBA, and 0.1 mg liter-1 GA₃. Multiple and rosetted adventitious shoots on the root of intact micropropagated plantlets were observed at the concentration of 2.193.29 mg•liter^-1 TDZ, whereas, single adventitious shoot formation was observed at 0.1 -1.10 mg •liter^-1 TDZ or 5.0 mg•liter^-1 BAP.
2. Among several factors in this experiment, cytokinin (BAP, TDZ) was most effective for adventitious shoot formation; casamino acid (1, 000 mg•liter^-1) had an additive effect.