Efficient plant regeneration via shoot organogenesis from explants of in vitro seedlings of a recalcitrant woody species of teak (Tectona grandis L.F.)
2015
In this study, adventitious shoot regeneration and rooting of shoots is reported from teak (Tectona grandis) seedlings. A factorial experiment was conducted with 4 explants (cotyledon, leaf, node, internode), 2 culture conditions (light, dark), 2 basal media (MS, WPM), 5 levels each of Dicamba, 2, 4-Dichlorophenoxyacetic acid, α-naphthaleneacetic acid, Picloram (1, 4, 9, 13, 20 µM) and Thidiazuron (0.001, 0.1, 1, 4, 10 µM) for callus induction from explants derived from 4-week-old-seedlings grown on MS agar-solidified medium along with 0.1% activated charcoal without sucrose. Callus induction varying in frequency was observed from all explant types at all TDZ levels on MS medium. However, 100% callus induction was obtained with 1 or 4 µM TDZ from nodal explants in dark after 7 weeks of initial culture. All NAA concentrations induced callus from nodal explants whereas 1 or 4 µM 2, 4-D was only effective for cotyledons. The calluses were then shifted to MS medium containing N6-benzyleadenine (BA), Kinetin or TDZ (0.5, 1, 4, 6 or 8 µM) in combination with indole-3-acetic acid, indole-3-butyric acid or NAA (0.5 µM) resulting in 45 combinations for shoot regeneration. Adventitious shoot regeneration (100%) with 42.25 shoots was obtained on MS medium supplemented with 8 µM TDZ after 17 weeks of culture. The regenerating shoots were elongated (5.14 cm shoot length) on MS medium supplemented with BA (8 µM) + IBA (1 µM) for 30 days. Such shoots were then rooted on half-strength MS medium with IBA + NAA (6+6, 8+8 or 10+10 µM). Rooting frequency of elongated shoots was 75.45% treated with 8+8 µM IBA and NAA with 1.65 mean number and 3.2 cm length after 35 days. The plantlets were successfully acclimatized with 55% survival in soil.
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