Linum lewisii Adventitious and Hairy-Roots Cultures as Lignan Plant Factories

Plants synthesize specific secondary metabolites for survival, reproduction, environmental
resilience, and defense. Among them, lignans are a class of polyphenols with several bioactive
properties: chemopreventive, anti-inflammatory, antiviral, and antioxidant. These compounds are
often extracted from field-grown plants with very low yields. To overcome these constraints, in vitro
tissue cultures provide a tool to optimize large-scale production. Moreover, the use of elicitation
to increase secondary metabolite production is gaining importance. The aim of this work was to
develop adventitious (ARL) and hairy roots (HRL) from Linum lewisi, a species able to synthesize
arylnaphthalene lignans such as justicidin B. The ARL and HRL were obtained for the first time
and characterized for their phenol content, antioxidant activity, and the production of justicidin B
after treatments with several elicitors and precursor feeding. Through NMR spectroscopy, other four
lignans were highlighted and identified in the roots extracts. A pilot-scale bioreactor was adopted to
assess the suitability of the developed root cultures for future large-scale production. The ARL and
HRL cultures showed a justicidin B production higher than other Linum species cultures described up
to now (75.8 mg/L and 82.2 g/L), and the production more than doubled after elicitation with MeJA.