Effects of different concentrations of growth regulators and explants type on callus induction, embryogenesis and shoot regeneration of Origanum vulgare ssp. Gracile

Origanum vulgar ssp. gracile is one of medicinal plants belonging to Lamiaceae family. Carvacrol was detected as a dominant component of essential oils of the species. Effects of different concentrations of 2,4-Dichlorophenoxy Acetic Acid (2,4-D) in combination with benzyl adenine (BAP) were investigated on callus induction of various explants (Cotyledon, Hypocotyl, Node, Shoot Tip and leaf) of the species.Interaction between culture media and explant types was significant at 1% Level of probability. The highest percentage of callus induction (100%) was obtained on MS medium supplemented with 1 and 3 mg l−1 2,4-D on node explants. Maximum callus induction (93.3%) was observed on MS medium supplemented with 3 mg l−1 2,4-D. No callus induction (0%) was observed on control and MS medium supplemented with 0.1 mg l−1 BA on leaf explants. Higher percentage of embryogenic callus production was obtained on MS medium supplemented with 1 mg l−1 2,4-D in combination with 0.1 mg l−1 BAP on shoot tip explants. Percentage of embryogenic induction was the lowest on hormone free MS medium and media containing 0.1 mg l−1 BAP in all explants and MS media supplemented with 5 mg l−1 2,4-D on hypocotyl explant. By increasing 2,4-D concentration, embryogenesis was decreased and maximum embryogenesis percentage was obtained by shoot tip and node explants. Effects of BAP on shoot regeneration from explants, the highest shoot regeneration (100%) on nodes and shoot tip explants on hormone free media and MS media fortified with 1 mg l−1 BAP were obtained.