IRON TRIGGERS A RAPID INDUCTION OF ASCORBATE PEROXIDASE GENE-EXPRESSION IN BRASSICA-NAPUS

In plants, only ferritin gene expression has been reported to be iron- dependent, Here it is demonstrated that an iron overload of Brassica n apus seedlings causes a large and rapid accumulation of ascorbate pero xidase transcripts, a plant-specific hydrogen peroxide-scavenging enzy me. This result documents a novel link between iron metabolism and oxi dative stress, The ascorbate peroxidase mRNA abundance was not modifie d by reducing agents like N-acetyl cysteine, glutathione and ascorbate or by pro-oxidants such as hydrogen peroxide or diamide, Furthermore, the iron-induced ascorbate peroxidase mRNA accumulation was not antag onized by N-acetyl cysteine, Abscisic acid had no effect on the ascorb ate peroxidase gene expression, Taken together these results suggest t hat iron-mediated expression of ascorbate peroxidase gene occurs throu gh a signal transduction pathway apparently different from those alrea dy described for plant genes responsive to oxidative stress. (C) 1997 Federation of European Biochemical Societies.