# A comparative analysis of the adaptability of salt stress between two flax (Linum usitatissimum L.) genotypes, Flanders and Astella, having contrasting lignan contents

## TL;DR

This study compares how two flax genotypes respond to salt stress, finding that Flanders is more resilient than Astella despite differences in lignan content.

## Contribution

The study identifies key variables influencing salt stress adaptation in flax and suggests microRNAs may play a central role in salinity tolerance.

## Key findings

- Flanders showed better growth and stress mitigation under salt stress compared to Astella.
- Flanders had higher antioxidant levels and lignan-related microRNAs, suggesting better cellular protection.
- Multivariate analysis did not confirm a direct role for lignans in stress adaptation.

## Abstract

A comparative analysis of NaCl-stressed flax genotypes reveals that microRNA828a, microRNA399g, microRNA168a, catalase, shoot length, and shoot dry weight are the most influential salt stress-responsive variables irrespective of the lignan (secoisolariciresinol diglucoside) content declared for the genotypes.

Lignans are powerful antioxidants and plant defence molecules whose roles in mitigating salt stress are rarely studied or understood, particularly in flax (Linum usitatissimum L.). Flax is a rich source of lignans. This study assessed the response to salt stress in two flax genotypes, Flanders and Astella. Astella has a higher content of the lignan secoisolariciresinol diglucoside (SDG) than Flanders. The 3-week-old flax plants were subjected to 100 mM NaCl salt stress for 1 week. Morphological analyses revealed that the growth of Flanders was more suppressed under stress, indicating resource-saving behaviour compared to Astella. Salt stress caused Astella to produce more reactive oxygen species (ROS) and incur more cell damage than Flanders. Flanders exhibited comparatively higher levels of antioxidants, osmoprotection machinery, and lignan-related microRNAs, suggesting its enhanced ROS scavenging and superior cellular protection capabilities than Astella. However, multivariate analysis could not provide evidence for the direct involvement of lignans in stress adaptation. Instead, it was hypothesised that microRNAs play a pleiotropic role in the adaptation to salinity. The results demonstrated Flanders’ superiority to Astella in salt stress mitigation. The findings could be used to improve the salinity tolerance of flax and other crop plants in future research.

The online version contains supplementary material available at 10.1007/s00425-025-04861-4.