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Abstract Detail

Heavy Metals and Phytoremediation

Benatti, Matheus R. [1], Guo, Woei-Jiun [2], Meetam, Metha [3], Goldsbrough, Peter [3].

Reduced Copper Tolerance and Accumulation in Metallothionein-Deficient Arabidopsis Mutants.

Metallothioneins (MTs) are low molecular mass, cysteine-rich peptides found across the animal and plant kingdoms, as well as in some prokaryotes. MTs have the capacity to bind a variety of heavy metals, providing a mechanism for metal ion homeostasis and detoxification in animals and fungi. In plants, the functions of MTs are still unknown. In Arabidopsis thaliana, seven actively expressed MT genes are present, with five being expressed predominantly in vegetative tissues and two expressed only in seeds. We have identified Arabidopsis lines with knock-out insertions in each of the MT genes, and developed plants deficient in all MTs that are highly expressed in vegetative tissues (MT1a, MT2a, MT2b and MT3). We are studying the involvement of MTs in metal ion accumulation during both vegetative and senescence stages. Preliminary results have shown that the quad-MT mutant (mt1a/mt2a/mt2b/mt3) develops normally with no alteration in metal ion accumulation under standard growth conditions. When grown in hydroponics supplemented with 5 µM Cu, the mt1a mutant accumulates approximately 30% less Cu in both roots and shoots than wild type plants. Under the same conditions, Cu accumulation in the quad-MT mutant is reduced by approximately 45% in shoots and 30% in roots, compared to wild type. Furthermore, the quad-MT mutant is hypersensitive to high concentrations of Cu (85 to 100 µM in MS media). These results provide direct evidence that plant MTs play important roles in metal homeostasis and accumulation. We are currently conducting complementation analysis with native MT genes to confirm that the phenotypes observed in MT-deficient plants are caused by the lack of MTs. In addition, grafting experiments between Arabidopsis mutants expressing HA epitope-tagged MTs and wild type plants will be used to test whether MTs can move intercellularly and mediate long-distance metal transport.

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1 - Purdue University, Department of Horticulture and Landscape Architecture, 625 Agriculture Mall Dr., West Lafayette, IN, 47907-2010, USA
2 - Institute of Plant and Microbial Biology, Academia Sinica, Taiwan
3 - Purdue University, Department of Botany and Plant Pathology

Arabidopsis thaliana
heavy metal
metal ion homeostasis
metal ion accumulation
oxidative stress
Cu sensitivity.

Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P05011
Abstract ID:426

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