Histological Studies of Somatic Embryogenesis in Eruca sativa Mill

Somatic embryos were induced from cotyledon explants cultured on Murashige and Skoog(MS)medium supplemented with 1.0 mg·L-1 2,4-D after two weeks of culture.Embryogenic callus proliferated profusely on MS medium containing 0.2 mg·L-1 2,4-D.Somatic embryos matured on N6 medium and developed into plantlets by culturing the mature somatic embryos on 1/2MS medium containing 0.1 mg·L-1indole-3-butyric acid.Section and microscopic observation of different developmental stages revealed that somatic embryogenesis was similar to that of the zygotic embryo.It originated from a single embryogenic cell,which had bigger nuclei,thick cytoplasm,clear nucleoli and denser order.The embryogenic cell first divided into two-celled stage proembryo,then three-or four-celled stage proembryo.Three-or four-celled stage proembryo developed into multicellular proembryo,then developed into mature somatic embryo.