The metal ion transporter IRT1 is necessary for iron homeostasis and efficient photosynthesis in Arabidopsis thaliana.
The mutants irt1-1 and irt1-2 of Arabidopsis thaliana were identified among a collection of T-DNA-tagged lines on the basis of a decrease in the effective quantum yield of photosystem II. The mutations responsible interfere with expression of IRT1, a nuclear gene that encodes the metal ion transporter IRT1. In irt1 mutants, photosensitivity and chlorophyll fluorescence parameters, as well as abundance and composition of the photosynthetic apparatus, are significantly altered. Additional effects of the mutation under greenhouse conditions, including chlorosis and a drastic reduction in growth rate and fertility, are compatible with a deficiency in iron transport. Propagation of irt1 plants on media supplemented with additional quantities of iron salts restores almost all aspects of wild-type behaviour. The irt2-1 mutant, which carries an En insertion in the highly homologous IRT2 gene of Arabidopsis thaliana, was identified by reverse genetics and shows no symptoms of iron deficiency. This, together with the finding that irt1-1 can be complemented by 35S::IRT1 but not by 35S::IRT2, demonstrates that, although the products of the two genes are closely related, only AtIRT1 is required for iron homeostasis under physiological conditions.
Varotto
Claudio
C
Zentrum zur Identifikation von Genfunktionen durch Insertionsmutagenese bei Arabidopsis thaliana (ZIGIA), Max-Planck-Institut für Züchtungsforschung, Carl-von-Linné-Weg 10, 50829 Köln, Germany.
Maiwald
Daniela
D
Pesaresi
Paolo
P
Jahns
Peter
P
Salamini
Francesco
F
Leister
Dario
D
D000483:Alleles; D017360:Arabidopsis / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism*; D004251:DNA Transposable Elements / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D006706:Homeostasis; D017136:Ion Transport / Q000502:physiology; D007501:Iron / Q000378:metabolism*; D045342:Light-Harvesting Protein Complexes; D016254:Mutagenesis, Insertional; D009154:Mutation; D010641:Phenotype; D010788:Photosynthesis / Q000235:genetics / Q000502:physiology*; D045322:Photosynthetic Reaction Center Complex Proteins / Q000235:genetics / Q000378:metabolism; D045332:Photosystem II Protein Complex; D010860:Pigments, Biological / Q000378:metabolism; D018515:Plant Leaves / Q000235:genetics / Q000502:physiology; D010940:Plant Proteins
D029681:Arabidopsis Proteins; D002352:Carrier Proteins; D027682:Cation Transport Proteins; D004251:DNA Transposable Elements; C099651:IRT1 protein, Arabidopsis; C434452:IRT2 protein, Arabidopsis; D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D010860:Pigments, Biological; D010940:Plant Proteins; D007501:Iron