Document Type: Research Paper
Department of Horticultural Sciences, Gorgan University of Agricultural Sciences and Natural Resources, P.O.Box 49138-15739, Gorgan, I.R. Iran.
Evening primrose (Oenothera biennis L.) is a wild flower with high and valuable oil content. High seed
shattering, indeterminate inflorescence and heterogeneous germination limit the commercial cultivation of
this 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 and
somatic embryogenesis accelerate the breeding process. In the present study, callus formation was
accomplished in MS (Murashik and Skoog) medium, but no embryogenesis was observed in the presence
or 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 callus
production 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 design
experiment with 4 replications. For embryogenesis, mhypocotyls (1cm long) were cultured in B5 liquid medium
at the induction phase. After 3 weeks, induced organs were sub-cultured to realization phase and the
number of embryos (different stages of embryogenesis) was counted 4 weeks later. The results indicated
that 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 of
embryos after the realization phase revealed largenuclei and abundance of starch grains indicating the
presence of embryonic cells in evening primrose hypocotyls.