Propagation of Vatica diospyroides Symington: An Endangered Medicinal Dipterocarp of Peninsular Thailand by Cultures of Embryonic Axes and Leaf-derived Calli

Embryonic axes and young leaves of Vatica diospyroides Symington were excised sterilely and then cultured on MS medium supplemented with 0-20 mg L-1 of a growth regulator and 0-0.3% Activated Charcoal (AC). The growth regulators tested were 2, 4-Dichlorophenoxyacetic acid (2,4-D), α-Naphthaleneacetic acid (NAA) and 3, 6-Dichloro-2-methoxybensoic acid (Dicamba). Vigorous shoot development was observed with 0-20 mg L-1 of each plant growth regulator and 0.1-0.15% AC. Shoot-derived calli were obtained 6 months after culturing embryonic axes on MS medium, with 15 mg L-1 dicamba and 0.1% AC. Interestingly, after culturing young leaves for 2 months, the highest weight of compact calli (0.40 g) was achieved with a medium containing 20 mg L-1 dicamba and 0.1% AC, in darkness. These were successfully multiplied by renewing and culturing in the same medium and transfer to shooting induction in MS medium supplemented with 0-20 mg L-1 6-benzyladenine (BA). Unfortunately, shoot induction from calli was unsuccessful and despite initiated roots being induced. A successful in vitro propagation protocol of V. diospyroides should be thus investigated more extensively.