Effects of 2,4 dichlorophenoxy acetic acid (2,4-D) on callus development of six Ocimum species

Since the demand in pharmaceutical industries for plant based raw materials is ever increasing. The present study is a stepping stone for in vitro callusdevelopment of six Ocimum species. Callus cultures were initiated from shoot tip and leaf explants for all species of Ocimum viz. O. basilicum, O. sanctum, O. canum, O. kilimandcharicum, O. minimum and O. americanum on Murashige and Skoog (1962) medium containing basic salts and 30 g/l sucrose supplemented with different concentrations (0.5, 1.0, 1.5 and 2.0 mg/l) of 2, 4-dichlorophenoxy acetic acid (2,4-D). Callus induction was observed in all supplemented medium for both explants but callogenesis frequency varied. Higher frequency of callus induction was recorded using shoot tip as explant than leaf explant in maximum Ocimum species. Compact callus was observed in O. kilimands charicum and O. sanctum while others formed friable callus. This method is useful for providing sufficiently large amounts of undifferentiated tissue and cells for genetic transformation studies and for suspension culture to produce larger amount of secondary metabolites.