PMID:19304929

Citation	Klatte, M, Schuler, M, Wirtz, M, Fink-Straube, C, Hell, R and Bauer, P (2009) The analysis of Arabidopsis nicotianamine synthase mutants reveals functions for nicotianamine in seed iron loading and iron deficiency responses. Plant Physiol. 150:257-71
Abstract	Nicotianamine chelates and transports micronutrient metal ions in plants. It has been speculated that nicotianamine is involved in seed loading with micronutrients. A tomato (Solanum lycopersicum) mutant (chloronerva) and a tobacco (Nicotiana tabacum) transgenic line have been utilized to analyze the effects of nicotianamine loss. These mutants showed early leaf chlorosis and had sterile flowers. Arabidopsis (Arabidopsis thaliana) has four NICOTIANAMINE SYNTHASE (NAS) genes. We constructed two quadruple nas mutants: one had full loss of NAS function, was sterile, and showed a chloronerva-like phenotype (nas4x-2); another mutant, with intermediate phenotype (nas4x-1), developed chlorotic leaves, which became severe upon transition from the vegetative to the reproductive phase and upon iron (Fe) deficiency. Residual nicotianamine levels were sufficient to sustain the life cycle. Therefore, the nas4x-1 mutant enabled us to study late nicotianamine functions. This mutant had no detectable nicotianamine in rosette leaves of the reproductive stage but low nicotianamine levels in vegetative rosette leaves and seeds. Fe accumulated in the rosette leaves, while less Fe was present in flowers and seeds. Leaves, roots, and flowers showed symptoms of Fe deficiency, whereas leaves also showed signs of sufficient Fe supply, as revealed by molecular-physiological analysis. The mutant was not able to fully mobilize Fe to sustain Fe supply of flowers and seeds in the normal way. Thus, nicotianamine is needed for correct supply of seeds with Fe. These results are fundamental for plant manipulation approaches to modify Fe homeostasis regulation through alterations of NAS genes.
Links	PubMed PMC2675739 Online version:10.1104/pp.109.136374
Keywords	Alkyl and Aryl Transferases/genetics; Arabidopsis/enzymology; Arabidopsis/genetics; Arabidopsis/metabolism; Arabidopsis Proteins/metabolism; Azetidinecarboxylic Acid/analogs & derivatives; Azetidinecarboxylic Acid/metabolism; Basic Helix-Loop-Helix Transcription Factors/metabolism; Copper/metabolism; Copper/toxicity; Flowers/enzymology; Flowers/genetics; Flowers/metabolism; Homeostasis; Iron/metabolism; Iron/toxicity; Phenotype; Plant Leaves/enzymology; Plant Leaves/genetics; Plant Leaves/metabolism; Reproduction/genetics; Seeds/enzymology; Seeds/genetics; Seeds/metabolism; Stress, Physiological; Zinc/metabolism; Zinc/toxicity
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
ARATH:NAS4	enables	GO:0030410: nicotianamine synthase activity	ECO:0000316: genetic interaction evidence used in manual assertion	AGI_LocusCode:At1g09240 AGI_LocusCode:At5g04950 AGI_LocusCode:At5g56080	F		Seeded From UniProt	complete
ARATH:NAS4	acts_upstream_of_or_within	GO:0030418: nicotianamine biosynthetic process	ECO:0000316: genetic interaction evidence used in manual assertion	AGI_LocusCode:At1g09240 AGI_LocusCode:At5g04950 AGI_LocusCode:At5g56080	P		Seeded From UniProt	complete

References

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