Cumin regeneration from seedling derived embryogenic callus in response to amended kinetin
Callus was induced from hypocotyl and primary leaf explants of cumin ( Cuminum cyminum L.) seedlings on a medium with 4 µM 2,4-D alone or plus 2 or 4 µM kinetin. An embryogenic callus developed within 2 weeks after transferring the callus to medium lacking plant growth regulators (PGR). The presence of kinetin in the callus induction medium with 2,4-D enhanced both the callus proliferation and the subsequent differentiation of the embryoids on the PGR-free medium. Plumules with or without simultaneously developed roots were observed 3–4 weeks after subculturing the embryogenic callus on medium containing 0.5 or 1.0 µM kinetin. Subsequently, they were transferred onto half-strength medium supplemented with 1 µM indole-3-butyric acid (IBA) and 2% polyethylene glycol (PEG, 6000) for root induction and/or proliferation, and in vitro hardening of the regenerated plants. The survival rate ex vitro was 70%. No plants developed from the embryogenic callus continuously incubated on medium lacking kinetin. We concluded that kinetin is crucial for plant regeneration from the induced embryoids of cumin.