Résumé
Salt stress is a major environmental challenge for plants, leading to various physiological and biochemical responses. This study investigates the impact of salt stress on lipid peroxidation, phenolic and flavonoid accumulation, free-radical scavenging antioxidant activity, glutathione content, tocopherol levels in three amaranth (Amaranthus caudatus L) genotypes: Red Cascade (Red), Green Cascade (Green), and Pony Tail Mixed (Pony). The results showed that, under salt stress, lipid peroxidation increased, causing cell membrane damage and compromising cell integrity. However, salt stress also triggered the accumulation of phenolic and flavonoid compounds, which possess strong antioxidant properties and play a crucial role in scavenging reactive oxygen species. The total antioxidant activity as measured by DPPH inhibition was significantly enhanced in all genotypes under salt stress, with the Green genotype showing the highest activity. Additionally, salt stress induced an increase in total glutathione levels, maintaining the GSH/GSSG ratio relatively constant in all genotypes. However, tocopherol content decreased significantly under salt stress, with the Green genotype being the most affected. Finally, as membrane compounds are affected by oxidative stress, an analysis of membrane trafficking in root epidermal cells revealed that the Pony genotype had the highest response of the three genotypes. Overall, these findings suggest that salt stress induces complex responses in A. caudatus genotypes, involving oxidative damage, phenolic and flavonoid accumulation, enhanced antioxidant activity, and alterations in tocopherols and enhanced membrane trafficking. Understanding these responses can contribute to the development of salt-tolerant crops and improve agricultural productivity under saline conditions.