Plant regeneration from callus cultures derived from mature zygotic embryos in white pine (Pinus strobus L.)

Plant regeneration via adventitious shoot organogenesis from callus cultures initiated from mature embryos in white pine ( Pinus strobus L.) was achieved in this study. Callus cultures were induced from mature embryos cultured on PS medium supplemented with 2,4-dichlorophenoxyacetic acid, alpha-naphthaleneacetic acid, or indole-3-acetic acid. Adventitious shoot regeneration from callus cultures was induced on medium containing 2 mu M indole-3-butyric acid ( IBA) and 3 - 12 mu M N-6-benzylaminopurine, thidiazuron (TDZ), or 6-(gamma,gamma-dimethylallylamino) purine. Sucrose was the most suitable sugar for adventitious shoot organogenesis in white pine. Shoot organogenesis was improved by treatment at 4 degrees C for 6 weeks. The frequency of adventitious shoot formation increased when 0.1 mM putrescine was added to basal medium supplemented with 6 mu M TDZ and 2 mu M IBA. Putrescine improved adventitious shoot organogenesis by decreasing lipid peroxidation. These findings provide useful information on adventitious shoot organogenesis and may be valuable to genetic transformation in white pine.