XVI International Botanical Congess

As the major soluble thiol in most cells, the tripeptide glutathione (GSH) is a redox buffer and underpins numerous defensive pathways. Many threats are associated with accelerated synthesis and/or increased concentrations of GSH. To identify factors controlling GSH synthesis and to generate plants containing more GSH, poplar was transformed to overexpress the synthetic enzymes in the chloroplast or cytosol. Overexpression in either location of the first enzyme of GSH synthesis markedly increased GSH contents without affecting glutathione redox state, morphology or growth rates. Maximal GSH production required glycine formation in the photorespiratory pathway. As well as furthering our understanding of how GSH synthesis is regulated, the results show that this pathway may be successfully manipulated by the food and pharmaceutical industries.