Influence of Ontological Age on Adventitious Bud and Shoot Formation of Pawpaw [Asimina triloba (L.) Dunal] Nodal Explants

• Published in: HortScience Vol. 32; no. 3; p. 441
• Main Authors: Finneseth, C.L.H, Layne, Desmond R, Geneve, R.L
• Format: Journal Article
• Language: English
• Published: 01.06.1997
• ISSN: 0018-5345; 2327-9834
• DOI: 10.21273/HORTSCI.32.3.441E

Clonal propagation of pawpaw is currently limited to budding and grafting. A tissue-culture system to rapidly produce clonal material would be valuable for both production and preservation of germplasm. Forced scion wood, shoots from root cuttings, and seedlings were explant sources for ontologically mature, intermediate, and juvenile ages, respectively. Preliminary data indicated that nodal explants had more rapid adventitious shoot formation than shoot tip explants. Disinfestation protocols were developed for each explant source. Nodal explants were cultured on MS medium supplemented with 10 μM BA and 0.1 μM TDZ. Within 3 weeks, 60% of the seedling explants had expanded axillary buds, while no bud expansion was observed for explants of either the intermediate or mature sources. By 6 weeks, seedling axillary shoots had elongated and were suitable for subculture. By 8 weeks, multiple adventitious buds and shoots had formed on all seedling explants. At this same time, axillary shoots began to elongate on intermediate source explants, but mature source explants appeared to be recalcitrant. Explant exudation caused medium darkening, but, by reducing the transfer interval from 4 to 2 weeks, discoloration was minimized. Mature source explants were maintained in culture and after ≈7 months, axillary bud expansion occurred in a small percentage of these explants.