A gene encoding multidrug resistance (MDR)-like protein is induced by aluminum and inhibitors of calcium flux in wheat [Triticum aestivum]

• Published in: Plant and cell physiology 2002-02, Vol.43 (2), p.177-185
• Main Authors: Sasaki, T. (Bio-oriented Technology Research Advancement Inst., Omiya, Saitama (Japan)), Ezaki, B, Matsumoto, H
• Format: Article
• Language: English
• Subjects: ABC protein; ALUMINIUM; aluminum; Aluminum - pharmacology; Amino Acid Sequence; ATP Binding Cassette Transporter, Subfamily B - genetics; ATP-binding cassette protein; ATP-Binding Cassette Transporters - genetics; Base Sequence; BINDING PROTEINS; Calcium - pharmacology; Calcium Channel Blockers - pharmacology; DNA, Complementary - genetics; DNA, Complementary - isolation & purification; EGTA; ethylene glycol-bis(β-aminoethyl ether)-N; GENE EXPRESSION; Gene Expression Regulation - drug effects; Key words: ABC protein — Aluminum stress — Calcium homeostasis — MDR — Wheat (Triticum aestivum L.); lanthanum; MDR; MOLECULAR CLONING; Molecular Sequence Data; multidrug resistance; N′-tetraacetic acid; Plant Roots - drug effects; Plant Roots - genetics; RACE; rapid amplification of cDNA ends; reverse transcription-PCR; RT-PCR; ruthenium red; Sequence Homology, Amino Acid; STRESS; TaMDR1 gene; Triticum - drug effects; Triticum - genetics; TRITICUM AESTIVUM
• ISSN: 0032-0781; 1471-9053
• DOI: 10.1093/pcp/pcf025

A cDNA clone exclusively induced by aluminum (Al) was isolated from root apices of wheat (Triticum aestivum L.) by the differential display method. The predicted amino acid sequence exhibited homology to the multidrug resistance (MDR) proteins that is known as a member of the ATP-binding cassette (ABC) protein superfamily. Thus this gene was named TaMDR1 (Triticum aestivum MDR). TaMDR1 was induced as a function of Al concentration in the range from 5 to 50 microM, which is in the range of Al content in natural acid soil environment. The concentration required for the induction was lower in the Al-sensitive cultivar than in the Al-tolerant cultivar, indicating that the accumulation of TaMDR1 mRNA was associated with the events caused by Al toxicity rather than Al tolerance. TaMDR1 was significantly induced by the exposure to lanthanum, gadolinium and ruthenium red, which are known as inhibitors of calcium channels. Furthermore, decreasing of calcium ion in growth medium caused stimulation of the gene expression. These results suggested that the induction of TaMDR1 is caused by the breaking of calcium homeostasis which occurred at early stage of Al toxicity.