title: Yeast metallothionein in transgenic tobacco promotes copper uptake from contaminated soils.
abstract: Metallothioneins (MTs) are metal-binding proteins that confer heavy metal tolerance and accumulation in yeast. To augment higher plant metal sequestration, the yeast metallothionein (CUP 1) was introduced into tobacco plants. The CUP 1 gene expression and copper and cadmium phytoextraction were determined. To confirm transformation, selfed and kanamycin-resistant third generation plants were subjected to DNA blot and polymerase chain reaction (PCR) analysis. A 4 mM CuSO(4) stress for 7 days resulted in a decline in CUP 1 transcripts versus nonstress conditions. Despite low mRNA levels, CUP 1 transformants accumulated up to seven times more copper in older versus younger leaves during copper stress. Pooled leaves of transgenic plants grown in soils from copper stamp-sands contained two to three times the copper content as that of the control plants. Unlike some previous reports featuring MT overexpression in plants, CUP 1 seedlings did not significantly sequester or demonstrate tolerance to CdCl(2). Using this transgenic approach, yeast CUP 1 expression under nonstressed conditions contributed to copper metal phytoextraction during a subsequent copper challenge. This strategy could be incorporated into plants designed for enhanced phytoremediation of metal contaminants.
authors.affiliation: Biological, Environmental, and Geology Sciences, Department of Natural Sciences, University of Michigan-Dearborn, 4901 Evergreen Rd., Dearborn, Michigan 48128-1491, USA. jcthomas@umd.umich.edu
authors.forename: John C
authors.initials: JC
authors.lastname: Thomas
authors.forename: Elizabeth C
authors.initials: EC
authors.lastname: Davies
authors.forename: Farah K
authors.initials: FK
authors.lastname: Malick
authors.forename: Charles
authors.initials: C
authors.lastname: Endreszl
authors.forename: Chandra R
authors.initials: CR
authors.lastname: Williams
authors.forename: Mohammed
authors.initials: M
authors.lastname: Abbas
authors.forename: Sally
authors.initials: S
authors.lastname: Petrella
authors.forename: Krystal
authors.initials: K
authors.lastname: Swisher
authors.forename: Mike
authors.initials: M
authors.lastname: Perron
authors.forename: Ryan
authors.initials: R
authors.lastname: Edwards
authors.forename: Pam
authors.initials: P
authors.lastname: Osenkowski
authors.forename: Nicolas
authors.initials: N
authors.lastname: Urbanczyk
authors.forename: Wendy N
authors.initials: WN
authors.lastname: Wiesend
authors.forename: Kent S
authors.initials: KS
authors.lastname: Murray
authors.forename: Pam
authors.initials: P
authors.lastname: Ostenkowski
mesh_terms: D000595:Amino Acid Sequence; D001673:Biodegradation, Environmental; D003300:Copper / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D007220:Industrial Waste / Q000517:prevention & control; D008668:Metallothionein / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000378:metabolism*; D015202:Protein Engineering / Q000379:methods*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012037:Refuse Disposal / Q000379:methods; D012989:Soil Pollutants / Q000378:metabolism*; D014026:Nicotiana / Q000235:genetics* / Q000378:metabolism*
chemical_list: D005656:Fungal Proteins; D007220:Industrial Waste; D011994:Recombinant Proteins; D012989:Soil Pollutants; C007121:copper thionein; D003300:Copper; D008668:Metallothionein