Enhancement of somatic embryogenesis and production of developmentally arrested embryos in Nigrella sativa L.

Somatic embryogenesis of Nigella sativa was investigated with the objective of inducing and isolating somatic embryos for biosynthetic studies. Callus cultures were initiated from leaf, stem, and root explants of axenic seedlings on MSB5 basal medium supplemented with kinetin (0.46 mum) and 2,4-D) (4.5 or 13.5 mum) or NAA (5.4 or 16.2 mum) in the dark. Cultures initiated and subcultured on medium containing NAA produced friable callus with numerous roots regardless of explant type. Cultures initiated, subcultured, or both, on medium with low 2,4-D concentration produced shiny embryogenic masses. These cultures differentiated into somatic embryos on medium containing NAA. The embryos developed into leafy structures on basal medium devoid of growth regulators. When the ernbryogenic callus was transferred to liquid medium containing NAA, numerous embryos and clusters of embryos were released into the liquid medium but, in contrast to solid medium, development remained arrested at the early embryonic stages. The developmentally arrested embryos were tested for production of active constituents of N. sativa oil. Chemical names used: 2,4-dichlorophenoxyacetic acid (2,4-D); alpha-naph-thaleneacetic acid (NAA); kinetin (K).