An efficient method for production of Tunisian melon (Cucumis melo L. cultivars Maazoun and Beji) by somatic embryogenesis

Somatic embryogenesis in two Cucumis melo L. cultivars, Maazoun and Beji, mainly cultivated in the Center and the North of Tunisia was induced from in vitro cultures derived from cotyledons, hypocotyls and zygotic embryos. The initiation of embryos was influenced by the hormonal composition of the media, the source of explant and the genotype. The three explants were cultured on the basal Murashige and Skoog (MS) media (1962) with 2,4-dichlorophenoxyacetic acid, 2,4-D (0.25 to 1 mgL-1) and6-benzylaminopurine (BAP; 0.10 to 0.50 mgL-1), produced calluses with somatic embryos after two weeks of culture. For Beji cv., the highest percentage (62.50%) of embryogenesis was observed for cotyledons. The average embryo number per callus was 10.40. Embryogenesis induction for zygotic embryos reached 33.50% with 29 embryos per callus. However, the embryogenesis ability of hypocotyls did not exceed 12.50% (2.50 embryos per callus). Somatic embryogenesis for Maazoun cv. explants was less efficient. Embryos formation was observed only for cotyledons (29%) and zygotic embryos (25%). Cotyledonary staged embryos, when transferred to hormone free MS medium, germinated. The maximum germination rates were 51.50 and 44.50%, respectively for Maazoun and Beji cv. The highest percentage (36.50%) of survival plants was noted for Beji cv. Regenerants were morphologically similar to their parents issued from seeds.   Key words: Cucumis melo L. cultivars, Maazoun, Beji, tissue culture, somatic embryogenesis; plant regeneration.