Optimization of embryogenic callus induction and indirect regeneration in saffron (Crocus sativus L.)

Saffron is a sterile triploid plant which is propagated by a daughter corms from the mother corm, thus improving its agronomic characteristics has been limited using conventional plant breeding. Tissue culture technology is a useful tool to improve crop characteristics. The purpose of this research is to find the appropriate protocol for the induction of callus in parts of saffron corms. A factorial experiment was carried out with plant growth regulators 2,4-D and BAP, at three levels (1, 2 and 3 mg/L) each, with 5 replications in a completely randomized design. The control samples had no any kind of growth regulator. These results indicate that MS culture medium supplemented with 2 mg/L 2,4-D and 2 mg/L BAP was the best culture medium for callus growth and formation. The purpose of this study was to achieve a suitable protocol for inducing embryogenic callus and indirect regeneration in saffron. To achieve this, an experiment was conducted in a completely randomized design with four replications using two growth regulators of 2,4-D, 0.5 mg/L, and BAP at three levels of 3, 4 and 5 mg/L. Observations showed that there were no significant differences between treatments. Then, these calluses were sub-cultured into two different levels of MS medium (half-strength MS and complete MS) without ABA with 3% and 6% sucrose, and with 1 mg/L ABA. The factorial experiment was conducted in a completely randomized design with 6 replications to examine embryo development. The results showed that the best medium for embryo development was complete MS medium containing 1 mg/L ABA. Finally, in order to growth and differentiation, these calluses were transferred to a MS medium with 6% sucrose. The observations indicated that calluses in full MS medium containing 1 mg/L ABA, showed the best reaction to regeneration.