Role of Nicotianamine in the Intracellular Delivery of Metals and Plant Reproductive Development

• Published in: The Plant cell Vol. 15; no. 6; pp. 1263 - 1280
• Main Authors: Takahashi, Michiko, Terada, Yasuko, Nakai, Izumi, Nakanishi, Hiromi, Yoshimura, Etsuro, Mori, Satoshi, Nishizawa, Naoko K.
• Format: Journal Article
• Language: English
• Published: England American Society of Plant Biologists 01.06.2003
• Subjects: Alkyl and Aryl Transferases - genetics; Alkyl and Aryl Transferases - metabolism; Amino Acid Sequence; Anthers; Azetidinecarboxylic Acid - analogs & derivatives; Azetidinecarboxylic Acid - metabolism; Biological Transport; Calyx; Citrates; Fertility; Flowers - growth & development; Flowers - metabolism; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant; Graftage; Hordeum - genetics; Hordeum - growth & development; Hordeum - metabolism; Hypochromic anemia; Iron - metabolism; Iron Radioisotopes; Leaves; Metals; Metals - metabolism; Molecular Sequence Data; Nicotiana - genetics; Nicotiana - growth & development; Nicotiana - metabolism; Petals; Plant Leaves - growth & development; Plant Leaves - metabolism; Plant Proteins - genetics; Plant Proteins - metabolism; Plants; Plants, Genetically Modified; Pollen; Seeds; Tobacco; Transaminases - genetics; Transaminases - metabolism; Zinc - metabolism
• ISSN: 1040-4651; 1532-298X
• DOI: 10.1105/tpc.010256

Nicotianamine (NA), a chelator of metals, is ubiquitously present in higher plants. Nicotianamine aminotransferase (NAAT) catalyzes the amino group transfer of NA in the biosynthetic pathway of phytosiderophores and is essential for iron acquisition in graminaceous plants. The gene that encodes NAAT from barley was introduced into the nongraminaceous plant tobacco, which produces NA but not phytosiderophores. Transgenic tobacco plants (naat tobacco) that constitutively expressed the NAAT gene had young leaves with interveinal chlorosis and flowers that were abnormally shaped and sterile. Endogenous NA was consumed as a result of NAAT overproduction in naat tobacco. The resulting NA shortage caused disorders in internal metal transport, leading to these abnormal phenotypes. In addition to its role in long-distance metal transport, NA may be involved in the regulation of metal transfer within the cells. These results suggest that a shortage of NA impaired the functions of metal-requiring proteins, including transcription factors.