Friable embryogenic callus and somatic embryo formation from cotyledon explants of African marigold (Tagetes erecta L.).

Embryogenic callus and somatic embryos were induced from cotyledonary explants of African marigold (Tagetes erecta L.). Cotyledons were first cultured on MS medium supplemented with 2.0 mg l 2,4-D and 0.2 mg l kinetin. After 5 weeks, calli were transferred to MS medium supplemented with 0.02 mg l thidiazuron where compact embryogenic callus developed. Friable embryogenic callus developed when the compact embryogenic callus was transferred to medium containing 2,4-D and subcultured every 2 weeks. Friable embryogenic callus has been maintained for more than 2 years without losing the capacity to generate embryos. Embryo development was obtained when friable embryogenic callus was transferred to MS medium supplemented with 3 mg l ABA and 60 g l sucrose. The addition of 10-30 mM L-glutamine improved embryo development.