Arsenic, cobalt and nickel tolerances in two populations of Silene vulgaris (Moench) Garcke from Ontario, Canada

Abstract

SUMMARYA population of Silene vulgaris (Moench) Garcke collected from mine tailings near the town of Cobalt, Ontario was compared in its metal tolerance with a population collected at an uncontaminated site (Baymouth, Ontario). Seedlings of the Cobalt population were tolerant to elevated levels of arsenic, cobalt and nickel, both compared with the Baymouth population and with other literature reports for this species. However, the tolerance indices in the Cobalt plants for these toxic elements did not correlate well with their concentration in water extractions in the mine soils.Indices of arsenic tolerance, based on the inhibition of root growth in 12 d experiments, showed a similar response to that in a 28 d experiment for both populations. The latter however, appeared to be a more accurate indicator of As tolerance in S. vulgaris, because the longer-term tolerance indices had lower standard deviations and higher probabilities for tolerance than the short-term tolerance indices. Reduced uptake of As occurred in the roots of tolerant individuals compared with non-tolerant individuals at a low As treatment. At a higher arsenic exposure, however, arsenic entered the roots of tolerant individuals. A partial exclusion or reduced translocation of arsenic to the shoots then appeared to operate in the shoots of tolerant individuals, i.e. arsenic levels were higher in shoots of non-tolerant plants. At the highest arsenic exposure, where the individuals from the Cobalt population were no longer tolerant, this exclusion pattern broke down. From a preliminary selection experiment, some arsenic tolerant individuals occurred in the Baymouth population. This suggests that under circumstances of arsenic contamination this population also has the potential to develop a tolerance to high arsenic exposure.

Toxicity of arsenate in Silene vulgaris, accumulation and degradation of arsenate‐induced phytochelatins

“…Even when the As : P ratio of the soil is as high as 200, the As : P ratio in the plant does not rise above 0.5 (Meharg et al, 1994). This was also found in our experiment where the As : P ratio within the plant never exceeded 0.27, even in the low-phosphate treatment in which the As : P ratio in the nutrient solution was 10 (data not shown).Root length growth has been used by various authors to determine the toxicity of arsenate (Rocovich & West, 1975 ;Porter & Peterson, 1977 ;Pollard, 1980 ;Paliouris & Hutchinson, 1991 ; De Koe et al, 1992 ;Macnair et al, 1992 ;Meharg & Macnair, 1992a ;Meharg et al, 1993). However, these tests were always performed over short time periods.…”

“…Toxicity of As in plants has been studied most extensively in grasses (Rocovich & West, 1975 ;Porter & Peterson, 1977 ;Pollard, 1980 ; De Koe et al., 1992 ;Macnair et al, 1992 ;Meharg & Macnair, 1992a ;Meharg et al, 1993), although some work has been published on dicotyledonous species (Paliouris & Hutchinson, 1991). However, these were all shortterm studies, and the toxicity of As in chronically exposed plants remains unclear.…”

“…Root length growth has been used by various authors to determine the toxicity of arsenate (Rocovich & West, 1975 ;Porter & Peterson, 1977 ;Pollard, 1980 ;Paliouris & Hutchinson, 1991 ; De Koe et al, 1992 ;Macnair et al, 1992 ;Meharg & Macnair, 1992a ;Meharg et al, 1993). However, these tests were always performed over short time periods.…”

Effect of Arsenic on Germination of Isatis Cappadocica Desv., a Newly Discovered Arsenic Hyperaccumulator

“…Paliouris and Hutchinson (1991) observed no effect of arsenate on germination of Silene vulgaris (Moench) Garcke seeds even at concentrations up to 20 mg As L -1 . The As content of our seedlings increased markedly with the increasing As in the medium; it was significantly lower in D. sofia (lower As tolerance) than in I. cappadocica (higher As tolerance) (Fig.…”

Effect of genotype, Cr(III) and Cr(VI) on plant growth and micronutrient status in Silene vulgaris (Moench)

“…The tolerance of many S. vulgaris ecotypes has been proven for most of heavy metal and their combinations, especially Cd, Cu, Fe, Mn, Pb, Zn and Hg (Paliouris & Hutchinson, 1991;Ernst & Nelissen, 2000;Ciarkowska & Hanus-Fajerska, 2008). Data from these studies show S. vulgaris to be an interesting species in the early stages of revegetation and soil restoration.…”