Adventitious shoot regeneration from leaf thin cell layers in apple

The present investigation was conducted to study organogenesis of a conventionally easy-to-regenerate (‘Royal Gala’) and a difficult-to-regenerate (‘Freedom’) apple cultivar using leaf transverse thin cell layers (tTCLs). The position of the leaf source, explant type and light regime applied to tTCLs were investigated as was their influence on the organogenic outcome. Light during the onset of regeneration delayed morphogenesis or, in ‘Freedom’, completely inhibited organogenesis on leaf tTCLs. Genotype and initial position of the leaf also influenced percentage regeneration and number of regenerated shoots per explant. This study demonstrates the successful application of leaf tTCLs for adventitious shoot regeneration in apple, even though further studies are needed to increase the number of shoots more than control explants. Shoot regeneration from apple leaf tTCLs serves as an alternative protocol for studying fundamental and applied aspects of regeneration.