In vitro somatic embryogenesis from suspension cultures of Carica papaya L.

An efficient protocol for plant regeneration of Carica papaya through indirect somatic embryogenesis was developed. Initially, friable embryogenic calluses (75.12%) were induced on half-strength MS ( Murashige and Skoog, 1962) basal salts and vitamins, 400 mg l−1 of glutamine and 60 g l−1 sucrose supplemented with 2.0 mg l−1 2,4-D (2,4 dichlorophenoxyacetic acid). Maximum frequency (68.35%) of somatic embryo induction was achieved on embryo induction medium containing half MS basal salts and vitamins, 30 g l−1 sucrose and 1.0% activated charcoal. The effects of abscisic acid (ABA), sucrose, and different strengths of MS medium on somatic embryo maturation were also investigated. The highest number of cotyledonary embryos was produced on liquid half-strength MS medium with 10.5 mg l−1 ABA and 10.0 g l−1 sucrose. Somatic embryos at cotyledonary stage were transferred onto MS medium supplemented with 0.4 mg l−1 BAP (6-benzylaminopurine) and 0.02 mg l−1 NAA (α-naphthaleneacetic acid) showed regeneration efficiency of up to 62.32%. Plants with well-developed shoots and roots were subsequently hardened in a potting mixture enriched with vermiculite. This regeneration protocol assures a high frequency of somatic embryogenesis, maturation and regeneration into plants.