Protocols for callus and somatic embryo initiation for Hibiscus sabdariffa L. (Malvaceae): Influence of explant type, sugar, and plant growth regulators

A significant work about callus induction and somatic embryogenesis was realized for Hibiscus sabdariffa. Two genotypes (Hibiscus sabdariffa var. sabdariffa and Hibiscus sabdariffa var. altissima), 2 sugars (sucrose and glucose) and three concentrations (1 %, 2%, 3%) of each sugar, 3 explant types (root, hypocotyl, cotyledon) were used for tissue culture. Fourteen combinations of plant growth regulators (PGRs) in MS medium and five combinations of PGR in Driver and Kuniyuki (DKW) medium were tested on hypocotyl and cotyledon for callus and somatic embryo formation. The PGR combinations used with MS medium were naphthaleneacetic acid/kinetin (NAA/KIN), 2,4-dichlorophenoxyacetic acid/kinetin (2,4-D/KIN), and naphthaleneacetic acid/6-benzylaminopurine (NAA/BA) and those used with DKW medium were 2,4-dichlorophenoxyacetic acid/thidiazuron (2,4-D/TDZ). Callus formation was initiated on both genotypes with all concentrations of both sugars and PGRs and in all explant types. The best results for callus induction were achieved with 3% sucrose and the hypocotyl and cotyledon explants. Somatic embryos were obtained with DKW medium supplemented with 4 mg/l 2,4-D + 1 mg/l TDZ and 1 mg/l 2,4-D + 0,5 mg/l TDZ.