ISHS Acta Horticulturae 812: III International Symposium on Acclimatization and Establishment of Micropropagated Plants
MICROPROPAGATION OF TWO ELITE BIRCH SPECIES THROUGH SHOOT PROLIFERATION AND REGENERATION |
| Authors: | V.A. Magnusson, C.M. Castillo, W. Dai |
| Keywords: | Betula platyphylla, Betula papyrifera, organogenesis |
| Abstract:
Two birch species, Betula platyphylla ‘VerDale’ and Betula papyrifera ‘Varen’, were micropropagated through shoot proliferation from existing buds and regeneration from in vitro tissues. Shoots were proliferated in either MS (Murashige and Skoog) or WPM (Woody Plant Medium) media supplemented with different cytokinins. Overall, benzyladenine (BA) at 10-20 and thidiazuron (TDZ) at 4-8 μM in WPM medium proliferated more shoots than other treatments (with an average of 4.3 for ‘Varen’ and 4.0 for ‘VerDale’ shoots per explant proliferated). In vitro shoots were regenerated from both cultivars when leaf or petiole explants were cultured in WPM media containing cytokinins. Betula papyrifera ‘Varen’ was easier to be regenerated than B. platyphylla ‘VerDale’. No shoots were produced and the original explants were dead after 6-8 weeks culture if no cytokinins were present. Among the three cytokinins (BA, zeatin, and TDZ), zeatin was most effective in shoot regeneration. Dark treatment for two or four weeks significantly increased the regeneration rate for both species. With a four-week dark treatment, an average of 18.5% leaf and 12.5% petiole explants produced shoots in the medium containing 40-100 μM zeatin, whereas only 2.7% of leaf and 2.5% of petiole explants regenerated shoots in the same medium without dark treatment. In vitro shoots were easily rooted in half-strength MS medium with 1-10 μM indole-3-butyric acid (IBA) or naphthalene acetic acid (NAA). Rooted plants were transferred to potting mix and grown in the green house. | |
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