KMID : 0368420070500010001
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Journal of Plant Biology 2007 Volume.50 No. 1 p.1 ~ p.7
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Chloroplast-targeted BrMT1 (Brassica rapa type-1 metallothionein) enhances resistance to cadmium and ros in transgenicatabidopsis plants
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Kim Sun-Ha
Lee Hyun-Sook Song Won-Yong Choi Kwan-Sam Hur Yoon-Kang
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Abstract
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Metallothioneins (MTs) are low-molecular-weight, cysteine-rich proteins that bind to heavy metals. Type-1 MTs function under various abiotic stresses, including exposure to the cadmium ion. We have now isolated theBrassica rapa type-1 metallothioneirt gene (BrMT1)using yeast systems, and have found that it confers resistance to Cd in otherwise Cd-sensitive yeast. Using a constitutive CaMV35S promoter and an RbsS transit peptide, we successfully targeted BrMT1 to the chloroplastsof Arabidopsis. Overexpression in either the chloroplasts or the cytosol effectively detoxified cadmium and H2O2 stresses in transgenicArabidopsis. in particular, the chloropfast-targeted BrMTl was associated with a significant reduction in paraquat-induced chlorosis and the accumulation of H2O2. This is the first report regarding the effects of type-1 MT1 targeted to chloroplasts. Our results suggest that this may be applicable to the development of plants with enhanced tolerance against environmental stresses.
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KEYWORD
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BrMTl, cadmium, DAB staining, H2O2, metallothioneins, ROS
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