High-efficiency Regeneration of Seedlings from Hypocotyl Explants of Tung Tree (Vernicia fordii)

Tung tree [Vernicia fordii (Hemsl.)Airy-Shaw] is one of the most important woody oil plants and provides the sole source of tung oil widely used in the industry.An efficient and reproducible in vitro regeneration method is required for genetic transformation in tung tree.In this study, we reported an effective and reproducible regeneration method for tung tree using hypocotyl explants.The optimum condition for callus induction was observed in woody plant medium (WPM) supplemented with 5.0 mg L -1 6-benzyladenine (BA), 1.0 mg L -1 kinetin (KT) and 0.1 mg L -1 α-naphthaleneacetic acid (NAA), with an induction rate of 100%.High frequency of shoot initiation was achieved in WPM supplemented with 1.0 mg L -1 6-BA, 0.05 mg L -1 NAA and 2.0 mg L -1 gibberellic acid (GA3), with an induction rate of 82.46%.Efficient shoot proliferation was obtained in WPM supplemented with 2.0 mg L -1 KT, 0.05 mg L -1 indole-3-acetic acid (IAA), and 2.0 mg L -1 GA3, with a multiplication index of 6.8.Shoot elongation and strengthening was noted in WPM supplemented with 1.0 mg L -1 NAA and 2.0 mg L -1 GA3.High rooting rate of 97.1% was achieved in 1/2 Murashige and Skoog (1962) (MS) medium supplemented with 0.1 mg L -1 indolebutyric acid (IBA).The well-rooted in vitro regenerated plantlets were successfully transferred to mixed substrates of peat moss: perlite: loess (1:1:1) and their survival rate reached 91.67% under natural environment.The efficient and reproducible in vitro regeneration method is established from hypocotyl explants, which could be applied for agrobacterium-mediated genetics transformation in tung tree.