Opportunities and feasibilities for biotechnological improvement of Zn, Cd or Ni tolerance and accumulation in plants
Hassan, Z. ; Aarts, M.G.M. - \ 2011
Environmental and Experimental Botany 72 (2011)1. - ISSN 0098-8472 - p. 53 - 63.
hyperaccumulator thlaspi-caerulescens - heavy-metal hyperaccumulation - cadmium-binding peptides - zinc-transporter genes - arabidopsis-thaliana - nicotianamine synthase - cellular compartmentation - subcellular-localization - phytochelatin synthase - expression d
Metals contaminate the soil when present in high concentrations causing soil and ultimately environmental pollution. “Phytoremediation” is the use of plants to remove pollutants from contaminated environments. Plants tightly regulate their internal metal concentrations in a process called “metal homeostasis”. Some species have evolved extreme tolerance and accumulation of Zn, Cd and Ni as a way to adapt to exposure to these metals. Such traits are beneficial for phytoremediation, however, most natural metal hyperaccumulator species are not adapted to agriculture and have low yields. A wealth of knowledge has been generated regarding metal homeostasis in plants, including hyperaccumulators, which can be used in phytoremediation of Zn, Cd and Ni. In this review, we describe the current state of Zn, Cd and Ni physiology in plants and the underlying molecular mechanisms. The ways to efficiently utilize this information in designing high biomass metal accumulator plants are discussed. The potential and application of genetic modification has extended our understanding about the mechanisms in plants dealing with the metal environment and has paved the way to achieve the goal of understanding metal physiology and to apply the knowledge for the containment and clean up of metal contaminated soils
Isolation of Zn-responsive genes from two accessions of the hyperaccumulator plant Thlaspi caerulescens
Hassinen, V.H. ; Tervahauta, A.I. ; Halimaa, P. ; Plessl, M. ; Peraniemi, S. ; Schat, H. ; Aarts, M.G.M. ; Servomaa, K. ; Karenlampi, S.O. - \ 2007
Planta 225 (2007)4. - ISSN 0032-0935 - p. 977 - 989.
zinc-transporter genes - heavy-metal tolerance - arabidopsis-thaliana - differential display - abc-transporter - accumulation - expression - metallothionein - identification - homeostasis
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.
Thlaspi caerulescens, an attractive model species to study heavy metal hyperaccumulation in plants.
Gonçalves Leite de Assunção, A. ; Schat, H. ; Aarts, M.G.M. - \ 2003
New Phytologist 159 (2003). - ISSN 0028-646X - p. 351 - 360.
zinc-transporter genes - arabidopsis-halleri - cadmium uptake - nickel hyperaccumulation - contaminated soils - nonmetallicolous populations - cellular compartmentation - metallicolous populations - molecular physiology - zn hyperaccumulator
Studying heavy metal hyperaccumulation is becoming more and more interesting for ecological, evolutionary, nutritional, and environmental reasons. One model species, especially in the era of high throughput genomics, transcriptomics, proteomics and metabolomics technologies, would be very advantageous. Although there are several hyperaccumulator species known, there is no single model species yet. The Zn, Cd and Ni hyperaccumulator species Thlaspi caerulescens has been studied to a great extent, especially for Zn and Cd hyperaccumulation and tolerance. Its physiological, morphological and genetic characteristics, and its close relationship to Arabidopsis thaliana, the general plant reference species, make it an excellent candidate to be the plant heavy metal hyperaccumulation model species