Effect of different plant growth regulators on responses of different explants in Callus induction of Java Tea (Orthosiphon stamineus Benth.)

The present study was carried out to identify the most suitable explants of Orthoszphon starnineus Benth. for callus induction to determine the most appropriate concentration of plant growth regulators combination for the callus induction, and to identify the appropriate medium for somatic embryo formation. Three types of explants (leaf, petiole, and stem nodes) were surface sterilized with the variation of Clorox® concentration for establishment of aseptic culture. Murashige and Skoog (MS) medium with different concentrations of 1-napthalene acetic acid (NAA) and 2,4- dichlorophenoxyacetic acid (2,4-D) were tested to induce the callus. The highest fresh weight callus production was obtained from leaf explants after 4 weeks of culture and 75% of the leaf explants showed callus formation. MS medium supplemented with 0.5 mg 1-1 2,4-D produced 0.42 g of callus fresh weight and was found as the best medium for callus induction from leaf explants. On the other hand, MS medium supplemented with 1.0 mg 1-1 2,4-D + 2.0 ma r1 NAA induced the most calli growth (0.60 g) from leaf explants. The color of the callus produced were creamy white to pale green, greenish, as well as brownish in nature. For study of somatic embryo formation, eight combination concentrations of 6-benzylaminopurine (BAP) and 2,4-D were tested. However, no somatic embryos were induced in all concentrations of BAP (0.0- 1.5 mg 1.1) combined with 0.5 mg 1.1 2,4-D. Further study of somatic embryogenesis of Orthosiphon stamineus Benth. should be carried out to determine the best condition for the production of somatic embryos in this plant.