Adaptation of the Common Ice Plant to High Copper and Zinc Concentrations and Their Potential Using for Phytoremediation

Abstract

A facultative halophite Mesembryanthemum crystallinum L. (the common ice plant) was shown to grow successively at the high concentrations of Cu and Zn. Although 25 µ M CuSO 4 or 800 µ M ZnSO 4 retarded markedly plant growth, they did not interfere with the completion of plant development and the formation of viable seeds. In such plants, leaves accumulated more than 200 µ g of Cu and 1700 µ g of Zn per 1 g of dry weight. A damaging effect of heavy metals (HMs) was manifested in a reduced content of water in leaves and proline accumulation in them. As copper is a metal with transient valence, copper salts are more toxic than zinc salts, which was manifested in a stronger inhibition of the chlorophyll synthesis. Both HMs induced oxidative stress, as evident from increased activities of guaiacol peroxidase and lipoxygenase. Moderate Cu and Zn concentrations did not damage cell membranes in leaves, as evident from the absence of their action on electrolyte leakage either under optimum conditions or after heat treatment. A capability of a substantial HM accumulation by the common ice plant and their considerable transport to shoots (up to 50 µ g of Cu and 560 µ g of Zn per plant) make it possible to consider the common ice plant as a promising phytoremediator.

Water relations in plants subjected to heavy metal stresses

“…If soils are high in soluble salts (including heavy metal salts), the osmotic potential in the soil solution might be lower than the potential of the cell sap in root. Under these circumstances, the soil solution would severely restrict the rate of water uptake by plants Barceló et al (1986a) Leaf Phaseolus vulgaris Becerril et al (1989) Leaf Medicago sativa Becerril et al (1989) Leaf Triforium pratense Poschenrieder et al (1989) Leaf Helianthus annuus Kastori et al (1992) Root, shoot Oryza sativa Moya et al (1993) Shoot Lactuca sativa Costa and Morel (1994) Shoot Lupinus albus Costa and Morel (1994) Shoot Pisum sativum Hernández et al (1997) Leaf Silene vulgaris Schat et al (1997) Leaf Hordeum vulgare Vassilev et al (1997Vassilev et al ( , 1998 Kholodova et al (2005Kholodova et al ( , 2011 Root Nicotiana tabacum Bazihizina et al (2014) Root, shoot Beta vulgaris Sagardoy et al (2010) Mesembr. cryst.…”

“…Some adaptative mechanisms to the negative effects of heavy metals on water status were observed in facultative halophyte M. crystallinum, which represent a relatively high potential metal tolerance (Kholodova et al 2005(Kholodova et al , 2011. In short-time experiments with both metal ions, a reduction in root sap exudation and water deficits in leaf tissues became evident (Kholodova et al 2011).…”

Zinc tolerance and accumulation in stable cell suspension cultures and in vitro regenerated plants of the emerging model plant Arabidopsis halleri (Brassicaceae)

“…Inhibition of growth has been observed in M. crystallinum plants treated with greater than 100 M zinc and only moderate levels of zinc have been reported to be accumulated in the leaf tissue (Kholodova et al 2005). In contrast to A. halleri lines, cell suspension cultures of M. crystallinum showed severe inhibition of growth in the presence of increasing concentrations of zinc (Fig.…”

Inoculation with a bacterial consortium alleviates the effect of cadmium overdose in soybean plants

“…The protein carbonyl content in plant biomass was determined using the methods described in [33]; the soluble phenolics content as described in [34]; the activity of guaiacol peroxidase (GPX, EC 1.11.1.7) as described in [35]; and the activity of glutathionе-Stransferase (EC 2.5.1.18) as described in [36].…”

“…The homogenate was centrifuged at 10 000 g for 20 min at 4°С. The supernatant was used to determine enzyme activity [35].…”