XVI International Botanical Congess

Glutathione (GSH) has multiple functions. Its synthesis is catalyzed by g-glutamylcysteine synthetase (GSHI) and glutathione synthetase (GSHII). We isolated GSH1 and GSH2 cDNAs from Arabidopsis by complementation of GSH-deficient yeast mutants. Gene-disrupted strains (gsh1::HIS3 and gsh2::HIS3), will allow overexpression of corresponding plant cDNAs. Interactions between dichloroacetamide herbicide safeners and heavy metal stress in maize were studied as to their effects on GSH metabolism. The safeners caused protection against Cd toxicity, due to overproduction of GSH and of GSH-derived phytochelatins, involved in the sequestration of Cd. Arabidopsis cells were stepwise selected for resistancy towards buthionine sulfoximine (BSO), a specific inhibitor of GSHI. BSO tolerance in the selected cell lines was correlated with an increased level of GSH.