A putative novel role for plant defensins: a defensin from the zinc hyper‐accumulating plant, Arabidopsis halleri, confers zinc tolerance

• Published in: The Plant journal : for cell and molecular biology Vol. 47; no. 3; pp. 329 - 342
• Main Authors: Mirouze, Marie, Sels, Jan, Richard, Odile, Czernic, Pierre, Loubet, Stéphanie, Jacquier, Amaury, François, Isabelle E.J.A., Cammue, Bruno P.A., Lebrun, Michel, Berthomieu, Pierre, Marquès, Laurence
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.08.2006; Blackwell Science
• Subjects: Adaptation to environment and cultivation conditions; Agronomy. Soil science and plant productions; Amino Acid Sequence; Arabidopsis; Arabidopsis - drug effects; Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis halleri; Arabidopsis Proteins - chemistry; Arabidopsis Proteins - metabolism; Arabidopsis Proteins - physiology; Biological and medical sciences; Botany; Defensins - chemistry; Defensins - metabolism; Defensins - physiology; DNA, Complementary - physiology; Fundamental and applied biological sciences. Psychology; Gene expression; Genetics and breeding of economic plants; metal tolerance; Molecular Sequence Data; Phylogeny; plant defensin; Plants, Genetically Modified - anatomy & histology; Plants, Genetically Modified - metabolism; Plants, Genetically Modified - physiology; RNA, Messenger - metabolism; Saccharomyces cerevisiae; Saccharomyces cerevisiae - genetics; Sequence Alignment; Transgenic plants; Varietal selection. Specialized plant breeding, plant breeding aims; Zinc; Zinc - metabolism; Zinc - pharmacology; Zinc Sulfate - pharmacology; Arabidopsis; Tolerance; plant defensin; metal tolerance; Fungi; Complementary DNA; Gene; Cruciferae; Dicotyledones; Angiospermae; Above ground plant part; Ascomycetes; Spermatophyta; Transgenic plant; Arabidopsis halleri; Saccharomyces cerevisiae; zinc; Thallophyta
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1111/j.1365-313X.2006.02788.x

Summary The metal tolerance of metal hyper‐accumulating plants is a poorly understood mechanism. In order to unravel the molecular basis of zinc (Zn) tolerance in the Zn hyper‐accumulating plant Arabidopsis halleri ssp. halleri, we carried out a functional screening of an A. halleri cDNA library in the yeast Saccharomyces cerevisiae to search for genes conferring Zn tolerance to yeast cells. The screening revealed four A. halleri defensin genes (AhPDFs), which induced Zn but not cadmium (Cd) tolerance in yeast. The expression of AhPDF1.1 under the control of the 35S promoter in A. thaliana made the transgenic plants more tolerant to Zn than wild‐type plants, but did not change the tolerance to Cd, copper (Cu), cobalt (Co), iron (Fe) or sodium (Na). Thus, AhPDF1.1 is able to confer Zn tolerance both to yeast and plants. In A. halleri, defensins are constitutively accumulated at a higher level in shoots than in A. thaliana. A. halleri defensin pools are Zn‐responsive, both at the mRNA and protein levels. In A. thaliana, some but not all defensin genes are induced by ZnCl2 treatment, and these genes are not induced by NaCl treatment. Defensins, found in a very large number of organisms, are known to be involved in the innate immune system but have never been found to play any role in metal physiology. Our results support the proposition that defensins could be involved in Zn tolerance in A. halleri, and that a role for plant defensins in metal physiology should be considered.