Plant regeneration protocols for adventitious shoot organogenesis from apple (Malus domestica ‘Fuji’) leaf explants were developed in the present study. The effects of dark incubation periods in the early stages of culture, pre-treatment methods, the number of explants per culture container, the types of culture containers, and orientation of the explants on culture media were evaluated to determine the optimal shoot regeneration conditions for ‘Fuji’ apple leaf explants. Light incubation of explants produced almost no response, on the other hand, dark incubation of explants for 4 weeks at initial culture periods enhanced shoot regeneration frequency. Comparing the number of explants per container, the higher percentage of shoot regeneration was obtained with 9 explants per container than 4 explants. As a pretreatment before culturing, dipping in liquid regeneration medium containing 40 g/L of sorbitol for 2 hours showed the highest shoot formation rate, and the time of shoot formation period was found to be accelerated. The shoot regeneration percent and number of shoot per regenerating explants reached up to 87.5% and 4.7, respectively. The regenerated shoots were elongated and rooted on rooting medium, consisted of 1/4 MS medium with 0.2mg/L IBA. The plantlets were acclimatized successfully and the regenerated plants showed normal phenotypes.

Keywords: Apple, Culture method, Dark incubation, Shoot organogenesis