Adventitious shoot regeneration and rooting of Prunus serotina in vitro cultures

A complete regeneration protocol was developed for Prunus serotina Ehrh., an important hardwood species for timber and sawlog production in the central and eastern United States. Nodal sections were cultured on Murashige and Skoog (MS) medium supplemented with 4.44 micromolar 6-benzylaminopurine (BA), 0.49 micromolar indole-3-butyric acid (IBA), and 0.29 micromolar gibberellic acid (GA3). In vitro leaf explants of three genotypes were placed on woody plant medium (WPM) supplemented with 0, 2.27, 4.54, or 6.81 micromolar thidiazuron (TDZ) in combination with 0, 0.54, 1.07, or 5.37 micromolar naphthaleneacetic acid (NAA), and on WPM supplemented with 0, 4.44, 8.88, or 13.32 micromolar BA in combination with 0, 0.54, 1.07, or 5.37 micromolar NAA. Cultures were maintained either in continuous darkness for 5 weeks, or in the dark for 3 weeks and then transferred to a 16-hour photoperiod. TDZ and the genotype had a significant effect on the number of shoots regenerated. The maximum mean number of shoots regenerated per explant (5.05 +/- 1.14) was obtained with 2.27 micromolar TDZ plus 0.54 micromolar NAA with the 3-week dark period then light treatment. The highest percent shoot regeneration (38.3) and mean number of shoots (4.13 +/- 0.97) was obtained with 6.81 micromolar TDZ plus 1.07 micromolar NAA. The highest rooting (27%) of adventitious shoots and number of roots per shoot (2.3 +/- 0.2) was obtained with 2.5 micromolar IBA when shoots were maintained for 7 days in the dark on rooting medium before transfer to a 16-hour photoperiod. The highest rooting (70%) of nodal explant-derived stock cultures and number of roots per shoot (2.7 +/- 0.9) was also obtained with 2.5 micromolar IBA, but when shoots were maintained for 4 days in the dark before transfer to a 16-hour photoperiod. In total, 86% of the plantlets survived acclimatization to the greenhouse and 100% survival after overwintering in cold-storage.