Differential expression and regulation of iron-regulated metal transporters in Arabidopsis halleri and Arabidopsis thaliana - the role in zinc tolerance

• Published in: The New phytologist Vol. 190; no. 1; pp. 125 - 137
• Main Authors: Shanmugam, Varanavasiappan, Lo, Jing-Chi, Wu, Chia-Lin, Wang, Shan-Li, Lai, Chong-Cheong, Connolly, Erin L, Huang, Jing-Ling, Yeh, Kuo-Chen
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01-04-2011; John Wiley & Sons; Wiley Subscription Services, Inc
• Subjects: Accumulation; Adaptation, Physiological - drug effects; Adaptation, Physiological - genetics; Antibodies; Arabidopsis - drug effects; Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis halleri; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; Basic Helix-Loop-Helix Transcription Factors - genetics; Basic Helix-Loop-Helix Transcription Factors - metabolism; Cation Transport Proteins - genetics; Cation Transport Proteins - metabolism; FMN Reductase - genetics; FMN Reductase - metabolism; Gene Expression Profiling; Gene expression regulation; Gene Expression Regulation, Plant - drug effects; Genes; Genes, Plant; Heavy metals; Homeostasis; hyperaccumulator; Hyperaccumulators; Iron; Iron - pharmacology; Iron deficiency; iron homeostasis; IRT1; Membrane Transport Proteins - drug effects; Membrane Transport Proteins - genetics; Phenotypes; Plant Proteins - genetics; Plant Proteins - metabolism; Plant Roots - drug effects; Plant Roots - genetics; Plant Roots - metabolism; Plant Shoots - drug effects; Plant Shoots - genetics; Plant Shoots - metabolism; Plants; Pollution tolerance; Reductases; Reverse Transcriptase Polymerase Chain Reaction; Shoots; Stress, Physiological - drug effects; Stress, Physiological - genetics; Toxicity; Uptake; Yeasts; Zinc; Zinc - toxicity; zinc tolerance; Arabidopsis halleri; hyperaccumulator; IRT1; iron homeostasis; zinc tolerance
• ISSN: 0028-646X; 1469-8137
• DOI: 10.1111/j.1469-8137.2010.03606.x

• To avoid zinc (Zn) toxicity, plants have developed a Zn homeostasis mechanism to cope with Zn excess in the surrounding soil. In this report, we uncovered the difference of a cross-homeostasis system between iron (Fe) and Zn in dealing with Zn excess in the Zn hyperaccumulator Arabidopsis halleri ssp. gemmifera and nonhyperaccumulator Arabidopsis thaliana. • Arabidopsis halleri shows low expression of the Fe acquisition and deficiency response-related genes IRT1 and IRT2 compared with A. thaliana. In A. thaliana, lowering the expression of IRT1 and IRT2 through the addition of excess Fe to the medium increases Zn tolerance. • Excess Zn induces significant Fe deficiency in A. thaliana and reduces Fe accumulation in shoots. By contrast, the accumulation of Fe in shoots of A. halleri was stable under various Zn treatments. Root ferric chelate reductase (FRO) activity and expression of FIT are low in A. halleri compared with A. thaliana. Overexpressing a ZIP family member IRT3 in irt1-1, rescues the Fe-deficient phenotype. • A fine-tuned Fe homeostasis mechanism in A. halleri maintains optimum Fe level by Zn-regulated ZIP transporters and prevents high Zn uptake through Fe-regulated metal transporters, and in part be responsible for Zn tolerance.