Combination toxicology of metal enriched soils: physiological responses of a Zn- and Cd-resistant ecotype of Silene vulgaris on polymetallic soils.

Plants of an ecotype of Silene vulgaris (Caryophyllaceae) originating from a Cd-Pb-Zn mine at Plombiere (Belgium) were grown on 15 polymetallic soils for a full life-cycle to investigate physiological responses which can help explain previously reported disorders in plants. The degree of regulation of the metal concentration in the young seedlings was a very reliable indicator of the subsequent plant performance. Uptake of Zn could be regulated up to 200 nmol water-soluble Zn

Distribution of cadmium in leaves of cadmium tolerant and sensitive ecotypes of Silene vulgaris.

It has been postulated that vacuolar compartmentation might play an important role in naturally selected cadmium tolerance in Silene vulgaris (Moench.) Garcke (Bladder campion). Additionally, a tendency of heavy metals to accumulate in the epidermis has been reported. Since these factors would affect the distribution of cadmium in leaves, we determined the distribution of cadmium in leaves of cadmium tolerant and sensitive ecotypes of Silene vulgaris at different levels of exposure and at different time intervals. Cadmium concentrations were higher in leaves of sensitive plants than in those of cadmium tolerant ones after identical exposure to cadmium for a period of 8 days. The highest cadmium concentrations were found in the lower epidermis of plants of both ecotypes. The amount of cadmium located at the lower epidermis was highest for sensitive plants, although the stomatal density was lower in the sensitive ecotype than in the tolerant one. A possible explanation for this phenomenon is the weak relationship between transpiration (water flow) and element allocation. Our results support the hypothesis that vacuolar storage of cadmium plays an important role in the mechanism of cadmium tolerance in Silene vulgaris

Differential metal-specific tolerance and accumulation patterns among Thlaspi caerulescens populations originating from different soil types.

• Here, Thlaspi caerulescens populations from contrasting soil types (serpentine, calamine and nonmetalliferous) were characterized with regard to tolerance, uptake and translocation of zinc (Zn), cadmium (Cd) and nickel (Ni) in hydroponic culture. • Results showed that high-level tolerances were apparently metal-specific and confined to the metals that were enriched at toxic levels in the soil at the population site. • With regard to metal accumulation, results suggested that, unlike Zn hyperaccumulation, Cd and Ni hyperaccumulation were not constitutive at the species level in T. caerulescens. • In general, the populations under study exhibited a pronounced uncorrelated and metal-specific variation in uptake, root to shoot translocation, and tolerance of Zn, Cd and Ni. The distinct intraspecific variation of these characters provides excellent opportunities for further genetic and physiological dissection of the hyperaccumulation trait

QTL analysis of cadmium and zinc accumulation in the heavy metal hyperaccumulator Thlaspi caerulescens.

Thlaspi caerulescens (Tc; 2n = 14) is a natural Zn, Cd and Ni hyperaccumulator species belonging to the Brassicaceae family. It shares 88% DNA identity in the coding regions with Arabidopsis thaliana (At) (Rigola et al. 2006). Although the physiology of heavy metal (hyper)accumulation has been intensively studied, the molecular genetics are still largely unexplored. We address this topic by constructing a genetic map based on AFL

Quantitative Relationship between Phytochelatin Accumulation and Growth Inhibition during Prolonged Exposure to Cadmium in Silene vulgaris.

Phytochelatins (PCs) are known to detoxify heavy metals in plants. This study aimed to investigate the possibility of using PCs as a biomarker for chronic Cd toxicity in Silene vulgaris. For this purpose, the effects of Cd on growth rate, related to plant weight, and the PC concentrations were recorded throughout the bigger part of the vegetative phase. The lowest concentrations of Cd used, 1 and 2 μM, inhibited plant growth rates by 30 and 50%, respectively, independent of the weight of the exposed plants. Above an exposure concentration of 2 μM Cd, the toxic effect increased with plant weight. At 3.5 μM Cd, the plant growth rates were inhibited up to 90%. Further increases of the exposure concentration did not produce additional inhibition. Root PC concentrations correlated with growth inhibition only at the lower Cd concentrations, i.e. up to 2 μM Cd. Above this concentration the correlation was lost