In Vitro Indirect Somatic Embryogenesis and Secondary Metabolites Production in the Saffron: Emphasis on Ultrasound and Plant Growth Regulators

Abstract

In the present study, the effects of ultrasound and plant growth regulators on in vitro callogenesis and secondary metabolites production in saffron calli were investigated. Accordingly, the saffron corms surface sterilized, sonicated and cultured on different concentrations of plant growth regulators (0.5, 1, 2 and 4 mg L-1 2,4-D or NAA in combination with 0.5 and 1 mg L-1 Kin or BAP). The percentage of callus induction, callus yield (fresh weight) and embryogenic callus formation were recorded and secondary metabolites of calli were measured by UV/VIS spectrophotometer three months after culture. The results indicated that sonication of the saffron corm explants significantly increased the in vitro callus induction and growth. So, the highest callus induction (100%) and yield (4.68 g) was achieved with sonicated explants cultured on MS medium supplemented with 2 mg L-1 1-naphthaleneacetic acid (NAA) and 0.5 mg L-1 kinetin (Kin). Somatic embryogenesis was significantly influenced by plant growth regulator regimes and the MS medium supplemented with 0.5 mg L-1 2,4-dichlorophenoxyacetic acid (2,4-D) plus 0.5 mg L-1 6-benzylaminopurine (BAP) and 0.5 mg L-1 NAA plus 0.5 mg L-1 Kin exhibited the highest percentage (75 and 72, respectively) of somatic embryogenesis. Secondary metabolite content of the callus cells was significantly different among the plant growth regulator regimes and the highest production of picrocrocin and safranal were occurred on the medium containing 0.5 mg L-1 2,4-D plus 0.5 mg L-1 BAP and 1 mg L-1 NAA plus 1 mg L-1 BAP.