Glutathione causes a massive and selective induction of plant defense genes

The reduced form of glutathione (GSH), when supplied to suspension cultured cells of bean (Phaseolus vulgaris L.) at concentrations in the range 0.01 to 1.0 millimolar, stimulates transcription of defense genes including those that encode cell wall hydroxyproline-rich glycoproteins and the phenylpropanoid biosynthetic enzymes phenylalanine ammonialyase (PAL) and chalcone synthase (CHS) involved in lignin (PAL) and phytoalexin (PAL, CHS) production. Transcriptional activation of these genes leads to marked accumulation of the corresponding transcripts, contributing to a massive change in the overall pattern of protein synthesis which closely resembles that previously observed in response to fungal elicitor. GSH causes a marked increase in extractable PAL activity, whereas the oxidized form of glutathione, constituent amino acids, or other reducing agents are inactive. Possible roles of GSH in signaling biological stress are discussed.