Isolation of Zn-responsive genes from two accessions of the hyperaccumulator plant <Emphasis Type="Italic">Thlaspi caerulescens</Emphasis> |
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Authors: | V H Hassinen A I Tervahauta P Halimaa M Plessl S Peräniemi H Schat M G M Aarts K Servomaa S O Kärenlampi |
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Institution: | (1) Institute of Applied Biotechnology, University of Kuopio, P.O. Box 1627, 70211 Kuopio, Finland;(2) Institute of Biochemical Plant Pathology, GSF—National Research Center for Environment and Health, Oberschleissheim, Germany;(3) Department of Chemistry, University of Kuopio, Kuopio, Finland;(4) Ecology and Physiology of Plants, Faculty of Earth and Life Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands;(5) Laboratory of Genetics, Wageningen University, Wageningen, The Netherlands;(6) North Savo Regional Environment Centre, Kuopio, Finland |
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Abstract: | Several populations with different metal tolerance, uptake and root-to-shoot transport are known for the metal hyperaccumulator
plant Thlaspi caerulescens. In this study, genes differentially expressed under various Zn exposures were identified from the shoots of two T. caerulescens accessions (calaminous and non-calaminous) using fluorescent differential display RT-PCR. cDNA fragments from 16 Zn-responsive
genes, including those encoding metallothionein (MT) type 2 and type 3, MRP-like transporter, pectin methylesterase (PME)
and Ole e 1-like gene as well as several unknown genes, were eventually isolated. The full-length MT2 and MT3 sequences differ from those previously isolated from other Thlaspi accessions, possibly representing new alleles or isoforms. Besides the differential expression in Zn exposures, the gene
expression was dependent on the accession. Thlaspi homologues of ClpP protease and MRP transporter were induced at high Zn concentrations. MT2 and PME were expressed at higher
levels in the calaminous accession. The MTs and MRP transporter expressed in transgenic yeasts were capable of conferring
Cu and Cd tolerance, whereas the Ole e 1-like gene enhanced toxicity to these metals. The MTs increased yeast intracellular
Cd content. As no significant differences were found between Arabidopsis and Thlaspi MTs, they apparently do not differ in their capacity to bind metals. However, the higher levels of MT2 in the calaminous
accession may contribute to the Zn-adapted phenotype. |
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Keywords: | Cadmium Differential display RT-PCR Metal hyperaccumulation Thlaspi Zinc |
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