Plant Cd 2+ and Zn 2+ status effects on root and shoot heavy metal accumulation in Thlaspi caerulescens (original) (raw)
Related papers
Plant Science, 2003
Thlaspi caerulescens is one of the best-known heavy metal hyperaccumulating plant species. It exhibits the ability to extract metals from soils and accumulates them in shoots at extremely high concentrations, particularly zinc (Zn) and cadmium (Cd). Using T. caerulescens (J. and C. Presl, ecotype Prayon) and a closely related non-accumulator species T. arvense , greenhouse experiments were carried out to study shoot growth (dry matter production) and Zn and Cd uptake from a severely Zn-deficient calcareous soil (DTPA-Zn: 0.09 mg kg (1 soil) supplemented with increasing amounts of Zn (0, 0.05, 0.5, 5, 25 and 75 mg kg (1 soil) and Cd (0 and 25 mg kg (1 soil). Shoot dry matter production of T. caerulescens was severely depressed by Zn deficiency, while in T. arvense , Zn deficiency slightly reduced growth. At the lowest Zn supplies (0 and 0.05 mg Zn kg (1 soil), T. caerulescens showed very severe Zn deficiency symptoms, including decreased leaf size and development of chlorosis and whitish-brown necrosis on the younger leaves. These symptoms were slight in T. arvense . At the highest Zn supply, leaves of T. caerulescens did not show any symptoms, but in T. arvense there were some necrotic patches on the margins of older leaves, probably due to Zn toxicity. With increasing Zn supply from 0 to 75 mg kg (1 soil, shoot dry matter production was increased by 4-fold in T. caerulescens and only 1.3-fold in T. arvense . Supply of Cd resulted in marked decrease in shoot growth of T. arvense , particularly under low Zn supply, but had no effect on the growth of T. caerulescens . At the low soil Zn levels ( B/0.5 mg Zn kg (1 ) shoot Zn concentrations were lower in T. caerulescens compared with T. arvense , and were below 10 mg Zn kg (1 dry weight. However, at the high supplies of Zn (/5 mg Zn kg (1 ), shoot Zn concentrations were considerably higher in T. caerulescens than T. arvense . Increase in Zn supply from 0 to 75 mg kg (1 enhanced shoot Zn concentrations by 84-fold in T. caerulescens and only 8-fold in T. arvense . Shoot Zn concentrations of both species were not affected by Cd supply, while increase in Zn supply did not affect Cd concentrations in shoot of T. caerulescens , but markedly reduced them in T. arvense. The results demonstrate that T. caerulescens is extremely sensitive to Zn deficiency in soils, but tolerant to excessive accumulation of Zn and also Cd in shoot, while T. arvense is tolerant to Zn deficiency but not to accumulation of Zn and Cd in shoot. Hyperaccumulation of Zn in T. caerulescens possibly depends on the existence of high concentrations of plant-available Zn in soils, which suggests that root-based mechanisms associated with increasing metal availability in the rhizosphere (e.g., rhizosphere acidification or release of Zn-mobilizing organic compounds from roots) only play a minor role in metal hyperaccumulation by T. caerulescens . The findings also suggest that the processes causing the metal hyperaccumulation trait in T. caerulescens also cause this plant species to be sensitive to Zn deficiency stress. #
Journal of Hazardous Materials, 2009
Effects of zinc (Zn) and cadmium (Cd) interactions on root morphology and metal translocation in the hyperaccumulating ecotype (HE) and non-hyperaccumulating ecotype (NHE) of S. alfredii were investigated under hydroponic conditions. Specific root lengths (SRL), specific root surface areas (SRA) and specific root volumes (SRV) of the HE increased significantly when plant were treated with 500 M Zn or 100 M Cd + 500 M Zn, whereas these root parameters were significantly decreased for the NHE when plant were treated with 100 M Cd, 500 M Zn or 100 M Cd + 500 M Zn. SRL and SRA of the HE were mainly constituted by roots with diameter between 0.2-0.4 mm (diameter class 3 and 4) which were significantly increased in treatment of 500 M Zn or 100 M Cd + 500 M Zn, whereas in the NHE, metal treatments caused a significant decrease in SRL and SRA of the finest diameter class root (diameter between 0.1-0.3 mm). The HE of S. alfredii could maintain a fine, widely branched root system under contaminated conditions compared with the NHE. Relative root growth, net Cd uptake and translocation rate in the HE were significantly increased by adding 500 M Zn, as compared with the second growth period, where 100 M Cd was supplied alone. Cadmium and Zn concentrations in the shoots of the HE were 12-16 times and 22-27 times higher than those of the NHE under 100 M Cd + 500 M Zn combined treatment. These results indicate strong positive interactions of Zn and Cd occurred in the HE under 100 M Cd + 500 M Zn treatment and Cd uptake and translocation was enhanced by adding 500 M Zn.
Functional Plant Biology, 2006
In order to fully understand the hyperaccumulation process and to increase the potential of plants for phytoextraction purposes, there is a need for more investigation of hyperaccumulating species or populations. Five Swiss populations of Thlaspi caerulescens J. & C. Presl originating from non-metalliferous but naturally Cd-rich soils (1.1–9.2 mg Cd kg–1) were compared with Ganges and Prayon populations and a non-accumulating species, Thlaspi perfoliatum (L.) F.K. Meyer, for their tolerance (shoot and root dry weight and root length) and Cd hyperaccumulation in hydroponics (0, 1, 5, 10, 20 and 50 μm Cd). In the field, the Swiss populations accumulated Zn and clearly hyperaccumulated Cd (up to 505 mg Cd kg–1 dry weight). The general response was significantly different between populations but in general an increasing Cd concentration in solution led to a decrease in dry weight production and an increase in Cd concentration in shoots. The shoot dry weight was a more discriminating par...
Zinc and cadmium uptake by hyperaccumulator Thlaspi caerulescens grown in nutrient solution
Phytoremediation of heavy-metal-contaminated soils can be an inexpensive means to remove hazardous metals from soil. Two metallophytes, Thlaspi caerulescens (J. & C. Presl, a Zn and Cd hyperaccumulator) from Prayon, Belgium, and a Zn-tolerant ecotype of bladder campion [Silene vulgaris (Moench.) Garcke L.] from Palmerton, PA, were compared with tomato [Lycopersicon lycopersicum (L.) Karsten, metal intolerant] in nutrient solution to characterize Zn and Cd uptake and tolerance. Zinc and Cd were added to solutions at a 50:1 molar ratio to simulate concentrations often found on contaminated sites. Seven treatment concentrations were used, ranging (in half-log increments) from 3.16 \aM Zn + 0.063 uM Cd to 10000 uM Zn + 200 uMCd. Thlaspi caerulescens showed much greater tolerance to Zn/Cd treatments than the other species, with toxicity stress only apparent at the 10000 uM Zn/200 uM Cd treatment. In this treatment, shoot concentrations of Zn and Cd were 33600 and 1140 nig kg~', respectively.
Plant and Soil, 2004
Sedum alfredii Hance has been identified as a new zinc (Zn) hyperaccumulating plant species. In this study, the effects of cadmium (Cd) supply levels (control, 12.5, 25, 50, 100, 200, 400, 800 µmol Cd L −1) on the growth and cadmium accumulation and Zn supply on Cd accumulation in S. alfredii Hance were studied. The results showed that no reduction in shoot and root dry matter yields were noted when the plants were grown at Cd supply levels up to 200 µmol L −1 in nutrient solution. Slight stimulation on shoot growth was noted at relatively low Cd levels (25 to 100 µmol L −1). Cadmium concentrations in leaves and stems increased with increasing Cd supply levels, and reached a maximum of approximately 9000 and 6500 mg kg −1 (DW) at 400 µmol Cd L −1 , respectively. Root Cd concentration increased sharply only at relatively high Cd levels. Cadmium distribution in different parts of the plant was in the order: leaf > stem root. The amount of Cd accumulated in the shoots reached 2.9 and 3.2 mg plant −1 at external Cd levels of 200 and 400 µmol L −1 , respectively. The shoot/root Cd ratios were greater than 2 and more than 95% of the total Cd taken up by S. alfredii was translocated to the shoots at the external Cd levels ≤200 µmol L −1. The concentrations of P, Ca, Mg, B, Fe, Mn, Cu, and in the shoots and roots were influenced differentially by Cd treatments. High Zn supply (500 µmol L −1) enhanced Cd concentrations in the leaves and stems at the Cd levels ≤100 µmol L −1 , and root Cd concentration at the Cd levels ≤50 µmol L −1. These results indicate that S. alfredii has an extraordinary ability to tolerate and hyperaccumulate Cd and this is the first report of the new Cd hyperaccumulator S. alfredii Hance. The finding of Cd/Zn hyperaccumulation in S. alfredii Hance provides an important plant material for understanding the mechanisms of Cd/Zn co-hyperaccumulation and for phytoremediation of the heavy metal contaminated soils.
Zinc and cadmium uptake by hyperaccumulator Thlaspi caerulescens and metal …
Environmental Science & …, 1995
Phytoremediation of heavy-metal-contaminated soils can be an inexpensive means to remove hazardous metals from soil. Two metallophytes, Thlaspi caerulescens (J. & C. Presl, a Zn and Cd hyperaccumulator) from Prayon, Belgium, and a Zn-tolerant ecotype of bladder campion [Silene vulgaris (Moench.) Garcke L.] from Palmerton, PA, were compared with tomato [Lycopersicon lycopersicum (L.) Karsten, metal intolerant] in nutrient solution to characterize Zn and Cd uptake and tolerance. Zinc and Cd were added to solutions at a 50:1 molar ratio to simulate concentrations often found on contaminated sites. Seven treatment concentrations were used, ranging (in half-log increments) from 3.16 \aM Zn + 0.063 uM Cd to 10000 uM Zn + 200 uMCd. Thlaspi caerulescens showed much greater tolerance to Zn/Cd treatments than the other species, with toxicity stress only apparent at the 10000 uM Zn/200 uM Cd treatment. In this treatment, shoot concentrations of Zn and Cd were 33600 and 1140 nig kg~', respectively.
Plants
Heavy metal redistribution is relevant for the quality of edible crops and the suitability of hyperaccumulators for bioremediation. Root-to-shoot transfer via the xylem and redistribution in the aerial parts via the phloem differ between various heavy metals. In general, cadmium is more slowly released to the shoot than zinc (e.g., in wheat, bean, and lupin). However, rapid cadmium transport to the shoot was detected in the hyperaccumulator Solanum nigrum L. This is a key aspect in this article and might be important for bioremediation. The radionuclides 109Cd and 65Zn were used to investigate the respective influence of elevated cadmium or zinc in the root medium on the dynamics of the two heavy metals in S. nigrum. Although transport via the xylem to the leaves was similar for 109Cd and 65Zn, the further redistribution from older leaves to younger leaves, flowers, and fruits via the phloem was far less efficient for 109Cd than for 65Zn. Furthermore, the redistribution of 109Cd wit...
Cadmium and zinc share many similar physiochemical properties, but their 4 compartmentation, complexation and impact on other mineral element distribution in plant 5 tissues may drastically differ. In this study, we address the impact of 10-µM Cd or 50-µM Zn 6 treatment on ion distribution in leaves of a metallicolous population of the non-7 hyperaccumulating species Zygophyllum fabago at tissue and cell level, and the consequences 8 on the plant response through a combined physiological, proteomic and metabolite approach. 9