Callus induction and plantlet regeneration from mature embryos of indica rice (Oryza sativa L.) cultivar Kra Dang Ngah.

Hom Kra Dang Ngah is a kind of favorable indica rice in southern Thailand. It was selected for the present study because it is local variety and no regeneration system has been reported earlier. In order to improve its quality by the genetic transformation, the establishment of the suitable plantlet regeneration system is prerequisite. In this way, mature embryos from seeds were used to induce callus and establish the high efficiency plantlet regeneration system. The optimum medium was obtained by manipulating different concentrations various plant growth regulators (PGR). Experimental results showed that addition of 2 mg/L 2,4dichlorophenoxyacetic acid (2,4-D) in combination with 1.0 mg/L of α- naphthalene acetic acid ( NAA), 1.0 mg/L of 6-benzyladenine (6-BA) and 0.5 mg/L of kinetin (Kn) to callus induction medium which was MS medium gave the most suitable for embryogenic callus induction at 56.3 %. The calluses derived from seeds were well proliferated on MS medium supplemented with 1.0 mg/L 2, 4-D, 0.5mg/L indole-3-acetic acid (IAA), 0.25 mg/L 6-BA, 0.25 mg/L Kn without browning. It also indicated the highest capability of planlet regeneration. At the same time, 1.5 mg/L thidiazuron (TDZ) in combination with 1.0mg/L 2.4-D showed the most efficient in plantlet regeneration.