In Vitro Propagation of Camellia oleifera Abel. Using Hypocotyl, Cotyledonary Node, and Radicle Explants

Camellia oleifera Abel. is one of four major woody oil plants in the world. The objective of the current study was to evaluate the effect of different plant growth regulators (PGRs) and concentrations on direct organogenesis using cotyledonary nodes, hypocotyls, and radicle explants. High induction frequency of adventitious shoots were obtained from cotyledonary nodes, hypocotyls, and radicle explants (85.2%, 73.6%, and 41.0%, respectively) when cultured on half-strength Murashige and Skoog (1/2 MS) medium containing 2.0 mg.L-1 6-benzylaminopurine (BA) and 0.1 mg.L-1 indole-3-acetic acid (IAA). Microshoots from cotyledonary nodes, hypocotyls, and radicle explants were then transferred to 1/2 MS medium containing 2.0 mg.L-1 BA and 0.05 mg.L-1 indole-3-butyric acid (IBA) for shoot multiplication, resulting in 6.9 shoots per explant. The shoots were transferred to Woody Plant Medium (WPM) supplemented with various a-naphthalene acetic acid (NAA) and gibberellic acid (GA(3)) for shoot elongation. The mean length of shoots and the number of leaves per shoot were 3.7 and 6.6 cm, respectively, in WPM supplemented with 0.5 mg.L-1 NAA and 3.0 mg.L-1 GA3. The highest rooting of shoots (90.2%) or the number of roots per shoot (7.2) was obtained when elongated microshoots were transferred to 1/2 MS medium supplemented with 3.5% perlite, 1.0 mg.L-1 IBA and 2.0 mg.L-1 NAA. The rooted plantlets were successfully acclimatized in the greenhouse with a survival rate of 90.0%. The in vitro plant regeneration procedure described in this study is beneficial for mass propagation and improvement of C. oleifera through genetic engineering.