In vitro cultures of Linum usitatissimum L.: Synergistic effects of mineral nutrients and photoperiod regimes on growth and biosynthesis of lignans and neolignans.

The multipurpose plant species Linum usitatissimum famous for producing linen fibre and containing valuable pharmacologically active polyphenols, has rarely been tested for it's in vitro biosynthesis potential of lignans and neolignans. The current study aims at the synergistic effects of mineral nutrients variation and different photoperiod treatments on growth kinetics and biomass accumulation in in vitro cultures of Linum usitatissimum. Both nutrient quality and quantity affected growth patterns, as cultures established on Gamborg B5 medium had comparatively long exponential phase compared to Murashige and Skoog medium, while growth was slow but steady until last phases of the culture on Schenk and Hildebrandt medium. Similarly, we observed that boron deficiency and nitrogen limitation in culture medium (Gamborg B5 medium) enhanced callus biomass (fresh weight 413 g/l and dry weight 20.7 g/l), phenolics production (667.60 mg/l), and lignan content (secoisolariciresinol diglucoside 6.33 and lariciresinol diglucoside 5.22 mg/g dry weight respectively) at 16/8 h light and dark-week 4, while that of neolignans (dehydrodiconiferyl alcohol glucoside 44.42 and guaiacylglycerol-β-coniferyl alcohol ether glucoside 9.26 mg/g dry weight, respectively) in continuous dark after 4th week of culture. Conversely, maximum flavonoids production occurred at both Murashige and Skoog, Schenk and Hildebrandt media (both media types contain comparatively higher boron and nitrogen content) in the presence of continuous light. Generally, continuous dark had no significant role in any growth associated parameter. This study opens new dimension for optimizing growing conditions and evaluating underlying mechanisms in biosynthesis of lignans and neolignans in in vitro cultures of Linum usitatissimum.