Sterilization procedure and callus regeneration in black turmeric (Curcuma caesia)

Sterilization procedure, media composition, explants selection and control of physical environment are critical for successful cultures and callus induction with surface sterilization being very challenging in most plants. Five different sterilization methods were evaluated to come up with the best for subsequent use to establish an in vitro regeneration method for the induction of callus in Curcuma caesia using excised leaf and rhizome explants. Murashige and Skoog (MS) media supplemented with various concentration of 2,4-Dichlorophenoxy acetic acid (2,4-D)/Indole-3-acetic acid (IAA) (0.5- 5.0mg/L), singly or in combination with Benzyl aminopurine (BAP)/Kinetin (KIN) (0.1-5.0mg/L), 0.3% sucrose and 0.08% agar were used. The result of the sterilization procedures showed 15% NaHClO3 (5min) + 70% Ethanol (30s) + 0.1% HgCl2 (5min) to be the most effective in controlling contamination in C. caesia among all the treatments tested. The response to callus induction was found to depend on the type of explants used and growth regulators combination. Leaf explants gave the highest percentage of callus induction. Highest percentage of callus induction (66.70%) was obtained in the growth regulator combination of 2, 4-D (0.5mg/L) + BAP (0.1mg/L) and least (14.29%) in IAA (2.0mg/L) + BAP (0.5mg/L). Equal and higher concentration of 2, 4-D + BAP of 5.0mg/L each also provided better result (40.00%). No callus was obtained in all the single concentration of 2, 4-D used.