Evidence against a role of lipid peroxidation in the induction of glyceollin biosynthesis in Glycine max

Glyceollin synthesis induced by hydrogen peroxide was examined in relation to lipid peroxidation in 3-day-old soybean axes (Glycine max (L.) Merr, cv Trésor). Lipid peroxidation was investigated as a possible early step in the signal transduction mechanism leading to phytoalexin synthesis. Treatments with either antioxidant compounds such as 3-tert-butyl-4-hydroxyanisole (BHA), N,N′-diphenyl-1,4-phenylenediamine (DPPD) and tetraethylthiuram disulfide (DSF) or prooxidant compounds such as ascorbic acid (Asc) and 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox) resulted in alterations in the level of endogenous lipid hydroperoxides during the critical phase of induction of the glyceollin biosynthesis. However, these treatments did not affect either glyceollin production or phenylalanine ammonia-lyase (PAL) and chalcone reductase (CHR) mRNA accumulation. This work strongly argues against a causal link between lipid peroxidation and glyceollin synthesis after an H2O2-elicitor treatment.