Abstract
Linum usitatissimum commonly known as flax or linseed is an important medicinal plant, produces medicinally potent lignans, used in the treatment of several human diseases. Lignans limited production in the natural plants does not meet the increasing market demand. This study was conducted to establish an easy and rapid method for the in vitro micropropagation and production of potent lignans and antioxidant secondary metabolites in linseed. The results indicated that hypocotyl explants under the effects of thidiazuron (TDZ: 0.5 mg/L) + kinetin (Kn: 0.5 mg/L) in the basal growth media, resulted in the optimal shoot organogenesis parameters (shoot induction frequency: 86.87%, number of shoots: 6.3 +/- 0.36 and shoots length: 6.5 +/- 0.54 cm), in 4 weeks. Further, TDZ supplementation in the culture media efficiently activated the antioxidant system in the in vitro raised shoots, wherein maximum production of total phenolic content, TPC (34.33 +/- 0.20 mg of GAE/g DW); total flavonoid content, TFC (8.99 +/- 0.02 mg of QE/g DW); DPPH free radical scavenging activity (92.7 +/- 1.32%); phenylalanine ammonia-lyase activity, PAL (8.99 +/- 0.02 U/g FW); and superoxide dismutase expression, SOD (3.62 +/- 0.01 nM/min/mg FW) were observed in the shoot cultures raised in presence of TDZ: 0.5 mg/L + Kn: 0.5 mg/L. Nonetheless, considerable levels of pharmacologically active lignans such as secoisolariciresinol (SECO: 23.13-37.10 mg/g DW), secoisolariciresinol diglucoside (SDG: 3.32-3.86 mg/g DW) and an hydro secoisolariciresinol diglucoside (ANHSECO: 5.15-7.94 mg/g DW) were accumulated in the regenerated shoots. This protocol can be scaled up for the commercial production of linseed to meet the market demands for lignans.