Yeast metallothionein in transgenic tobacco promotes copper uptake from contaminated soils

• Published in: Biotechnology progress 2003, Vol.19 (2), p.273-280
• Main Authors: Thomas, J.C, Davies, E.C, Malick, F.K, Endreszl, C, Williams, C.R, Abbas, M, Petrella, S, Swisher, K, Perron, M, Edwards, R
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Biodegradation, Environmental; Biological and medical sciences; copper; Copper - metabolism; CUP1 gene; Fundamental and applied biological sciences. Psychology; Fungal Proteins - genetics; Fungal Proteins - metabolism; Gene Expression Regulation, Plant; Industrial Waste - prevention & control; metallothionein; Metallothionein - genetics; Metallothionein - metabolism; Molecular Sequence Data; Nicotiana - genetics; Nicotiana - metabolism; Nicotiana tabacum; phytoremediation; Plant Leaves - genetics; Plant Leaves - metabolism; Plants, Genetically Modified - metabolism; polluted soils; Protein Engineering - methods; Recombinant Proteins - genetics; Recombinant Proteins - metabolism; Refuse Disposal - methods; Soil Pollutants - metabolism; soil pollution; transgenic plants
• ISSN: 8756-7938; 1520-6033
• DOI: 10.1021/bp025623q

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 CuSO4 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 CdCl2. 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.