Linoleic acid alleviates aluminum toxicity by modulating fatty acid composition and redox homeostasis in wheat (Triticum aestivum) seedlings.

Lipids, as key components of biological membranes, play vital roles in sensing and initiating plant responses to various abiotic stresses. Here, the alteration of membrane fatty acids in wheat roots under Al stress was investigated using two genotypes differing in Al tolerance, and the role of linoleic acid in Al tolerance was comprehensively explored. Significant differences in the fatty acid profiles were observed, with increased linoleic acid accumulation in the Al-tolerant genotype. Supplementation with linoleic acid enhanced fatty acid synthesis, reduced membrane lipid saturation, improved membrane fluidity, and alleviated root growth inhibition. Wheat seedlings treated with linoleic acid exhibited a reduction in lipid peroxidation, as evidenced by decreased levels of malondialdehyde and lipid hydroperoxides. Furthermore, the application of linoleic acid increased the total contents and reduced forms of ascorbic acid (AsA) and glutathione (GSH), thereby restoring the cellular redox balance in wheat roots under Al stress. The elevated levels of AsA and GSH maintained by linoleic acid, can be attributed to the high efficiency of the AsA-GSH cycle, as linoleic acid enhanced the activities of the antioxidant enzymes involved. These results suggest that linoleic acid enhances wheat Al tolerance by maintaining both fatty acid synthesis and the levels of unsaturated fatty acids, as well as protecting membrane lipids from peroxidation by reactive oxygen species through the regulation of the AsA-GSH cycle.