Fe homeostasis in plant cells: Does nicotianamine play multiple roles in the regulation of cytoplasmic Fe concentration?

• Published in: Planta 2001-10, Vol.213 (6), p.967-976
• Main Authors: Pich, Axel, Manteuffel, Renate, Hillmer, Stefan, Scholz, Günter, Schmidt, Wolfgang
• Format: Article
• Language: English
• Subjects: Absorption. Translocation of ions and substances. Permeability; Adaptation, Physiological; Agronomy. Soil science and plant productions; Azetidinecarboxylic Acid - analogs & derivatives; Azetidinecarboxylic Acid - metabolism; Biological and medical sciences; Copper - metabolism; Cytoplasm; Economic plant physiology; Ferritins; Fundamental and applied biological sciences. Psychology; Gelatinases - antagonists & inhibitors; Homeostasis; Immunohistochemistry; Iron; Iron - metabolism; Iron - pharmacology; Leaves; Manganese - metabolism; Mutation; Nutrient solutions; Nutrition. Photosynthesis. Respiration. Metabolism; Peas; Pisum sativum - cytology; Pisum sativum - genetics; Pisum sativum - physiology; Plant cells; Plant Leaves - chemistry; Plant Leaves - drug effects; Plant Leaves - growth & development; Plant physiology and development; Plant roots; Plant Roots - chemistry; Plant Roots - drug effects; Plant Roots - growth & development; Plants; Solanum lycopersicum - cytology; Solanum lycopersicum - genetics; Solanum lycopersicum - physiology; Vacuoles; Vacuoles - metabolism; Water and solutes. Absorption, translocation and permeability; Zinc - metabolism
• ISSN: 0032-0935; 1432-2048
• DOI: 10.1007/s004250100573

The cellular and intracellular localization of the non-proteogenic amino acid nicotianamine (NA) in leaves and root elongation zones was immunochemically investigated in pea (Pisum sativum L.) and tomato (Lycopersicon esculentum Mill.) plants grown under various iron regimes and in three mutants defective in the regulation of iron uptake. Strongest immunostaining was observed in the over-accumulating pea mutants brz and dgl, and in iron-loaded wild-type plants. Fe concentration and NA level paralleled staining intensity, indicating that NA synthesis is induced by high iron availability. While label was mainly present in the cytoplasm under normal (10 μM) Fe supply and under Fe deprivation, most of the labeling was present in the vacuole in iron-loaded plants. This pattern resembled the distribution of NA in Fe over-accumulating mutants, indicating the possible importance of vacuolar sequestration in the detoxification of excess Fe. Based on the dependence of the cellular distribution of NA on the iron nutritional status of the plant, a possible role of NA in buffering free Fe in root and leaf cells was inferred. We show here for the first time that the NA concentration is increased in response to iron overload, indicating that, besides other classes of intracellular metal-binding ligands, NA may play an essential role in iron tolerance.