Sweet cherry (Prunus avium L.) 'Giorgia', adventitious regeneration from leaves of microplants

With the aim of exploiting the regenerative capability of sweet cherry (Prunus avium L.) 'Giorgia', experiments were carried out using suitable plant tissue cultures established in vitro. Relatively high percentages of adventitious shoot regeneration were consistently obtained from in vitro leaves, wounded by three cuts transversely to the midrib, excised from 3-week-old proliferating shoots. The regeneration capacity was influenced by the mineral salts and the plant growth regulator (PGR) composition of the regeneration medium: Woody Plant Medium (WPM) gave the best results and 22.7 mu M of 1-Phenyl-3-(1,2,3-thiazol-5-yl)urea (thidiazuron, TDZ) induced most adventitious regeneration. The pre-culture of the donor shoots on MS medium with phloroglucinol (PG)-added improved the regeneration rate. Histological studies demonstrated the origin of the adventitious shoots from callus formed by epidermal and sub-epidermal cells as well as by the inner cells of the vascular bundles.