Effect of l-glutamine and casein hydrolysate in the development of somatic embryos from cotyledonary leaf explants in okra (Abelmoschus esculentus L. monech)

Okra is an important vegetable crop and very few studies have been carried out for the development and in vitro regeneration of somatic embryos. In this study, we have developed an efficient protocol for somatic embryogenesis from cotyledonary leaf explants of Okra (Abelmoschus esculentus L. Monech). In this investigation, the genotype CoBhH1 of A. esculentus was tested with different amino acids and casein hydrolysate for the optimization culture conditions and development of somatic embryos. The explants were cultured on Murashige and Skoog (MS) medium containing Gamborgs (B5) vitamins, 400 mg/l l-glutamine, 300 mg/l casein hydrolysate, 8 g agar, 1.5 mg/l 2, 4-dichlorophenoxyacetic acid (2, 4-D) and 1 mg/l naphthaleneacetic acid (NAA). Proembryoids were observed after 4 weeks of regular subculturing in the same media. Globular to torpedo shaped somatic embryo development was observed after 8 weeks of culture. Mature embryos were selected by their cotyledonary stage and subcultured on the regeneration medium. Half strength MS medium containing B5 vitamin (half strength), 30 g sucrose, 8 g agar, 1 mg/l BAP and 0.5 mg/l GA3 were used for regeneration and shoot elongation. A total of 17.43 plantlets were obtained from single explant through this protocol. The plantlets were transferred to plastic cups in laboratory condition and finally transferred to the greenhouse with a 100% survival rate. Inter simple sequence repeats (ISSR) analysis was used to check the genetic fidelity of regenerated plants. No polymorphism was detected revealing the genetic integrity of regenerated plantlets. The regenerated plants were morphologically similar to those of the mother plant.