Molecular diversity and metal accumulation of different Thlaspi praecox populations from Slovenia (original) (raw)
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New Phytologist, 2004
Forty-seven populations of Thlaspi caerulescens in Luxembourg were characterised for population size, soil mineral element composition and other habitat characteristics. Foliar concentrations of eight elements were assessed in 15 populations in the field and in eight populations cultivated in zinc (Zn)-cadmium (Cd)-nickel (Ni)enriched soil. • T. caerulescens favoured stony soil developed on steep, south-facing Emsian shale outcrops. All soil samples were nonmetalliferous. Soil pH ranged from 4.2 to 6.9. Field-growing plants had very high concentrations of heavy metals in the leaves (Zn, 3000 -13 000 mg kg − 1 ; Cd, 11-44 mg kg − 1 ; Ni, 38 -473 mg kg − 1 ). Positive soil-plant correlations existed for Zn and Mn. • In cultivation, significant genetic variation was found for biomass and six of eight mineral elements. For Cd and Zn, variation range among 48 half-sib families was two-fold (Cd, 183-334 mg kg − 1 ; Zn, 8030 -16 295 mg kg − 1 ). Most of the variation occurred among populations, consistent with the selfing mating system of those populations. There was a tight Zn-Cd genetic correlation ( r = +0.83, P < 0.0001).
Noccaea caerulescens (Brassicaceae) is a major pseudometallophyte model for the investigation of the genetics and evolution of metal hyperaccumulation in plants. We studied the population genetics and demographic history of this species to advance the understanding of among-population differences in metal hyperaccumulation and tolerance abilities. Sampling of seven to 30 plants was carried out in 62 sites in Western Europe. Genotyping was carried out using a combination of new chloroplast and nuclear neutral markers. A strong genetic structure was detected, allowing the definition of three genetic subunits. Subunits showed a good geographic coherence. Accordingly , distant metallicolous populations generally belonged to distinct subunits. Approximate Bayesian computation analysis of demographic scenarios among subunits further supported a primary isolation of populations from the southern Massif Central prior to last glacial maximum, whereas northern populations may have derived during postglacial recolonization events. Estimated divergence times among subunits were rather recent in comparison with the species history, but certainly before the establishment of anthropogenic metalliferous sites. Our results suggest that the large-scale genetic structure of N. caerulescens populations pre-existed to the local adaptation to metalliferous sites. The population structure of quantitative variation for metal-related adaptive traits must have established independently in isolated gene pools. However, features of the most divergent genetic unit (e.g. extreme levels of Cd accumulation observed in previous studies) question the putative relationships between adaptive evolution of metal-related traits and subunits isolation. Finally, admixture signals among distant metallicolous populations suggest a putative role of human activities in facilitating long-distance genetic exchanges.
Plant Cell and Environment, 2008
A detailed localization of elements in leaf tissues of the field-collected Cd/Zn hyperaccumulator Thlaspi praecox (Brassicaceae) growing at a highly metal-polluted site was determined by micro-proton-induced X-ray emission (micro-PIXE) in order to reveal and compare nutrient and non-essential element accumulation patterns in the case of multiple metal accumulation within particular leaf tissues, including the detailed distribution between apoplast and symplast regions. On the larger scans, the highest concentrations of metals were observed in the epidermis, S and Ca in the palisade mesophyll, Cl in the spongy mesophyll and vascular bundles, and P and K in the vascular bundles. On the more detailed scans, the highest Cd, Pb, Cl and K concentrations were observed in vascular bundle collenchyma. The relative element distribution (%) was calculated based on concentrations of elements in particular leaf tissues and their relative weight portions, indicating that most of the accumulated Zn was located in epidermises, while the majority of Cd and Pb was distributed within the mesophyll. Detailed scans of epidermal/mesophyll tissues revealed that Zn was mainly accumulated and detoxified in the symplast of large vacuolated epidermal cells, Cd in the mesophyll symplast, and Pb in the mesophyll symplast and apoplast.
International Journal of …, 2008
Thlaspi caerulescens is an important component of specific vegetation on mine wastes in Central Slovakia including those containing high soil concentrations of Zn, Pb and Cd in Banská Štiavnica and Cu in Špania Dolina. The population density of T. caerulescens varied in both metalliferous and non-metalliferous soils. Selective distribution of metals was observed in T. caerulescens: Cu and Pb remained in the roots while Zn and Cd were hyperaccumulated in leaves. In the leaves of plants growing on metalliferous soils maximum concentrations were 19410 mg/kg Zn and 80 mg/kg Cd dry matter and on non-metalliferous soils 16670 mg/kg Zn and 127 mg/kg Cd dry matter. Hyperaccumulation and selective uptake were also confirmed by leaf/soil bioconcentration factors with a maximum of 317 for Cd and 370 for Zn, versus 0.07 for Pb and 0.46 for Cu obtained from non-metalliferous habitats.
Plant, Cell and Environment, 2003
hyperaccumulates Zn to > 1.0% of shoot dry biomass in its natural habitats, and can hyperaccumulate Ni to > 0.1% when growing on serpentine soils. Populations from the Ganges region of southern France also have a remarkable ability to accumulate Cd in their shoots to concentrations well in excess of 0.01% without apparent toxicity symptoms. Because hyperaccumulation of Cd appears to be highly variable in this species, the relationship between Cd tolerance and metal accumulation was investigated for seven contrasting populations of T. caerulescens grown under controlled conditions in solution culture. The populations varied considerably in average plant biomass (3.1fold), shoot : root ratio (2.2-fold), Cd hyperaccumulation (3.5-fold), shoot : root Cd-concentration ratio (3.1-fold), and shoot Cd : Zn ratio (2.6-fold), but the degree of hyperaccumulation of Cd and Zn were strongly correlated. Two populations from the Ganges region were distinct in exhibiting high degrees of both Cd tolerance and hyperaccumulation (one requiring 3 m m m m M Cd for optimal growth), whereas across the other five populations there was an inverse relationship between Cd tolerance and hyperaccumulation, as has been noted previously for Zn. Metal hyperaccumulation was negatively correlated with shoot : root ratio, which could account quantitatively for the differences between populations in shoot Zn (but not Cd) concentrations. On exposure to 30 m m m m M Cd, the two Ganges populations showed marked reductions in shoot Zn and Fe concentrations, although Cd accumulation was not inhibited by elevated Zn; in the other five populations, 30 m m m m M Cd had little or no effect on Zn or Fe accumulation but markedly reduced shoot Ca concentration. These results support a proposal that Cd is taken up predominantly via a high-affinity uptake system for Fe in the Ganges populations, but via a lower-affinity pathway for Ca in other populations. Total shoot Cd accumulated per plant was much more closely related to population Cd tolerance than Cd hyperaccumulation, indicating that metal tolerance may be the more important selection criterion in developing lines with greatest phytoremediation potential.
Plant physiology, 2015
Noccaea caerulescens (Thlaspi caerulescens), an extremophile heavy metal hyperaccumulator model plant in the Brassicaceae family, is a morphologically and phenotypically diverse species exhibiting metal tolerance and leaf accumulation of zinc, cadmium and nickel. Here we provide a detailed genome structure of the ~267-Mb N. caerulescens genome, which has descended from seven chromosomes of the ancestral Proto-Calepineae Karyotype (PCK, n = 7) through an unusually high number of pericentric inversions. Genome analysis in two other related species, N. jankae and Raparia bulbosa, showed that all three species - and thus probably entire Coluteocarpeae tribe - have descended from the PCK. All three analyzed species share the chromosome structure of six out of seven chromosomes and an unusually high metal accumulation in leaves, which remains moderate in N. jankae and R. bulbosa, and is extreme in N. caerulescens. Among these species, N. caerulescens has the most derived karyotype with sp...
Thlaspi caerulescens, an attractive model species to study heavy metal hyperaccumulation in plants
New Phytologist, 2003
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.
Genetics and Genomics of the Heavy Metal Hyperaccumulator Model Species Thlaspi caerulescens
In the last decade heavy metal hyperaccumulator plants have been increasingly studied, mainly because of their potential use in phytore-mediation. Thlaspi caerulescens is an attractive model hyperaccumulator plant, because it accommodates a high of intra-specific variation in the degrees and metal-specificity patterns of tolerance and accumulation. In this review we give an overview of recent progress made in the genetics and genomics of heavy metal hyperaccumulation in this species. QTL analysis for zinc and cadmium accumulation in segregating inter-accession crosses demonstrated that these traits are controlled by multiple genes and that there are accession-specific accumulation mechanisms with distinct metal-affinity patterns. Cross-species transcriptome analyses have revealed a large number of genes with differential expression between hyperaccumulators and non-hyperaccumulators. Many of those genes are known to be involved in metal homeostasis, and an even larger number might play a role in this process. However, most of the differentially expressed genes have probably no role in metal homeostasis, owing to the fact that species with different life history and ecology are compared. To confirm the role of candidate genes, mutant research is necessary, but not yet done in hyperaccumulators. In the absence of physical maps and full genome sequences of hyperaccumulators, comparative genomics are indispensable. Co-linearity and micro-synteny analysis should enable the identification of the genes responsible for QTL for accumulation traits in intra-and inter-specific crosses.
Cadmium Hyperaccumulation and Reproductive Traits in Natural Thlaspi caerulescens Populations
Plant Biology, 2006
During the last decade, the metal hyperaccumulating plants have attracted considerable attention because of their potential use in decontamination of heavy metal contaminated soils. However, in most species, little is known regarding the function, the ecological and the evolutionary significances of hyperaccumulation. In our study, we investigated the parameters influencing the Cd concentration in plants as well as the biological implications of Cd hyperaccumulation in nine natural populations of Thlaspi caerulescens. First, we showed that Cd concentration in the plant was positively correlated with plant Zn, Fe, and Cu concentrations. This suggested that the physiological and/or molecular mechanisms for uptake, transport and/or accumulation of these four heavy metals interact with each other. Second, we specified a measure of Cd hyperaccumulation capacity by populations and showed that T. caerulescens plants originating from populations with high Cd hyperaccumulation capacity had better growth, by developing more and bigger leaves, taller stems, and produced more fruits and heavier seeds. These results suggest a tolerance/disposal role of Cd hyperaccumulation in this species.