Effects of different combinations and concentrations of growth regulators and photoperiod on somatic embryogenesis of cucumis melo var. flexuosus

The present study describes the effects of medium, explant type and photoperiod on somatic embryogenesis of snake melon (Cucumis melo var. flexuosus). Two different types of explant (cotyledon and hypocotyls) obtained from 3 days old snake melon seedlings and culture conditions were investigated for somatic embryogenesis. Explants were cultured on Murashige and Skoog (1962) (MS) medium supplemented with 23 different combinations of auxins (2,4-dichlorophenoxyacetic acid, 2,4-D; a-naphthalene acetic acid, NAA) and cytokinin (6- benzylaminopurine, BAP; N6-[2-isopentyl]adenine, 2iP) either alone or in combination with each other. Embryogenic calluses were obtained from cotyledon explant on MS media supplemented with NAA and 2,4-D alone and combinations with cytokinin. Our findings showed that NAA and 2,4-D did not act synergistically with BAP or 2iP. Callus formation was the same whether BAP or 2iP was added into the media or not. The highest embryo formation was achieved from cotyledon explant which was 20.00c7.94 somatic embryos per petri dish on medium supplemented with 4 mg/l 2,4-D and 0.5 mg/l BAP. The cotyledon and hypocotyls explants cultured on the media with 2 mg/l 2,4-D with 0.5 mg/l BAP showed embryogenic callus formation and number of somatic embryos were 17.33c5.51 and 16.33c3.06 per petri dish, respectively. Auxin was found critical for formation of somatic embryo and at the same time, the two tested cytokinins at any concentration acted synergistically with auxin.