A Study on Evening-Primrose (Oenothera biennis L.) Callus Regeneration and Somatic Embryogenesis

Evening primrose (Oenothera biennis L.) is a wild flower with high and valuable oil content. High seedshattering, indeterminate inflorescence and heterogeneous germination limit the commercial cultivation ofthis plant. Besides agronomical research, breeding programs can also remedy the above mentioned problems.Since traditional breeding methods take a long time, using techniques such as tissue culture andsomatic embryogenesis accelerate the breeding process. In the present study, callus formation wasaccomplished in MS (Murashik and Skoog) medium, but no embryogenesis was observed in the presenceor absence of plant hormones like 2,4-D (2,4-dichlorophenoxy) acetic acid. In contrast, B5 (Gamborg) medium containing 2,4-D induced embryogenesis. Different parts of plants exhibited good callusproduction potency and the hypocotyl was found as the best plant explants. In B5 medium, various concentrations of 2,4-D (0,2.26 μM, 4.52 μM, and 9.04 μM) were applied as a complete randomized designexperiment with 4 replications. For embryogenesis, mhypocotyls (1cm long) were cultured in B5 liquid mediumat the induction phase. After 3 weeks, induced organs were sub-cultured to realization phase and thenumber of embryos (different stages of embryogenesis) was counted 4 weeks later. The results indicatedthat variation in hormone concentrations caused significant differences with respect to somatic embryogenesis.Embryo development were not observed in hormone-free media. The highest numbers of globular,heart, torpedo, cotyledonary, and total embryo was recorded at 9.04 μM of 2, 4-D. Histological studies ofembryos after the realization phase revealed largenuclei and abundance of starch grains indicating thepresence of embryonic cells in evening primrose hypocotyls.