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 napus seedlings causes a large and rapid accumulation of ascorbate peroxidase transcripts, a plant-specific hydrogen peroxide-scavenging enzyme. This result documents a novel link between iron metabolism and oxidative stress. The ascorbate peroxidase mRNA abundance was not modified 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 antagonized by N-acetyl cysteine. Abscisic acid had no effect on the ascorbate peroxidase gene expression. Taken together these results suggest that iron-mediated expression of ascorbate peroxidase gene occurs through a signal transduction pathway apparently different from those already described for plant genes responsive to oxidative stress.
Vansuyt
G
G
Biochimie et Physiologie Moléculaire des Plantes, CNRS URA 2133, ENSAM-INRA, Montpellier, France.
Lopez
F
F
Inzé
D
D
Briat
J F
JF
Fourcroy
P
P
D000040:Abscisic Acid / Q000494:pharmacology; D060387:Ascorbate Peroxidases; D001937:Brassica / Q000201:enzymology / Q000235:genetics*; D019343:Citric Acid; D018548:Cotyledon; D004790:Enzyme Induction; D005296:Ferrous Compounds / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D007501:Iron / Q000494:pharmacology*; D018384:Oxidative Stress; D010544:Peroxidases / Q000096:biosynthesis / Q000235:genetics*; D012333:RNA, Messenger / Q000378:metabolism
D005296:Ferrous Compounds; D012333:RNA, Messenger; D019343:Citric Acid; C016600:ferrous citrate; D000040:Abscisic Acid; D007501:Iron; D010544:Peroxidases; D060387:Ascorbate Peroxidases