Lignans Associated Differences in Salt Stress Responses of Flax (Linum usitatissimum L.) Genotypes In Vitro

The objective of this study was to investigate the association between lignan content and stress responses in flax genotypes with contrasting lignan levels. For this purpose, two flax (Linum usitatissimum L.) genotypes, Agram and CDC Bethune, were selected based on their differing lignan profiles. We quantified secoisolariciresinol diglucoside, pinoresinol, pinoresinol diglucoside, matairesinol, and lariciresinol in both control and salt-stressed plants. In parallel, antioxidant activity, flavonoid, polyphenols, and phenolic acid content were determined to assess the overall antioxidant potential and phenolic response under saline conditions. The Agram genotype appears to activate defense mechanisms that enhance antioxidant capacity, which is largely mediated by polyphenolic compounds and distinct patterns of microRNA regulation. By contrast, the CDC Bethune genotype primarily responds to salinity stress by inducing lignan biosynthesis. Differential lignan modulation, contrasting antioxidants and miRNA profiles, shows substantial intergenotypic differences in how flax activates distinct defense pathways.