Development of a high-frequency adventitious shoot regeneration using cotyledon explants of an important oilseed crop Sesamum indicum L.

Sesame (Sesamum indicum L.; 2n = 26) is an ancient oil-yielding crop known for its valuable nutrients such as essential fatty acids, proteins, and medicinally important lignans. Recalcitrant nature of sesame limits the use of modern biotechnology for its genetic improvement. For the development of an efficient in vitro regeneration protocol, the cotyledon (de-embryonated) explants were used for the development of adventitious shoots. In the present study, Murashige and Skoog (MS) medium with 25 μM BAP (6-benzylaminopurine) and 2 μM IAA (indole-3-acetic acid) showed high regeneration frequency in both GT-3 (33.3 ± 1.1%) and GT-4 (30 ± 0.0%) varieties within 6 wk of culture. Addition of 20 μM thidiazuron (TDZ) showed further improvement in regeneration frequency in both GT-3 (63.3 ± 1.1%) and GT-4 (26.7 ± 1.1%) varieties. In another experiment, 0-d-old cotyledons inoculated on MS medium supplemented with 4 μM abscisic acid (ABA) showed the highest shoot regeneration in GT-3 (83.3 ± 3.3%) and GT-4 (70.0 ± 0.1%) varieties after 6 wk. The regenerated shoots transferred on MS medium with 5 μM BAP and 2 μM IAA or 1 μM GA3 (gibberellic acid) showed good elongation. Maximum root induction frequency (70.0 ± 2.3%) was achieved on MS medium with 2 μM α-naphthalene acetic acid (NAA) after 4 wk. The sesame plants in green house showed normal vegetative growth and flowering. The regeneration protocol can be used for the transformation of sesame crop for genetic improvement.