Engineering increases in sulfur amino acid contents in flax by overexpressing the yeast Met25 gene

Plant infection is accompanied by an oxidative burst that produces free radicals of various natures. The approach that we exploited in this study was to increase the antioxidative potential of flax by genetic engineering. Overexpressing the yeast Met25 gene coding for O-acetylhomoserine-O-acetylserine (OAH-OAS) sulfhydrylase in flax resulted in a significant increase in cysteine and methionine biosynthesis. This overproduction of sulfur amino acids increases the synthesis of glutathione, a tripeptide containing cysteine. The increase in glutathione content in the transgenic plant increases its antioxidative potential, and thus improves the plant's protection against Fusarium infection.