Biochemical responses of Lemna minor experimentally exposed to cadmium and zinc

Abstract

The effects of 5 μM cadmium (Cd), a non-essential toxic element and 25 and 50 μM zinc (Zn), an essential micronutrient, were investigated in aquatic plant Lemna minor L. after 4 and 7 days of exposure to each metal alone or to their combinations. Both metals showed tendency to accumulate with time, but when present in combination, they reduced uptake of each other. Cd treatment increased the lipid peroxidation and protein oxidation indicating appearance of oxidative stress. However, Zn supplementation in either concentration reduced values of both parameters, while exposure to Zn alone resulted in elevated level of lipid peroxidation and protein oxidation but only on the 7th day. Enhanced DNA damage, which was found on the 4th day in plants treated with Cd alone or in combination with Zn, was reduced on the 7th day in combined treatments. Higher catalase activity obtained in all treated plants on the 4th day of experiment was reduced in Zn-treated plants, but remained high in plants exposed to Cd alone or in combination with Zn after 7 days. Cd exposure resulted in higher peroxidase activity, while Zn addition prominently reduced peroxidase activity in the plants subjected to Cd stress. In conclusion, Cd induced more pronounced oxidative stress and DNA damage than Zn in applied concentrations. Combined treatments showed lower values of oxidative stress parameters--lipid peroxidation, protein oxidation and peroxidase activity as well as lower DNA damage, which indicates alleviating effect of Zn on oxidative stress in Cd-treated plants.

Salix matsudana Koidz Tolerance Mechanisms to Cadmium: Uptake and Accumulation, Subcellular Distribution, and Chemical Forms

“…Peng et al [50] found that adding Mn to the solution containing Cd significantly improved plant growth and reduced the concentrations of Cd in all organs of the plant. Zn is known to play a crucial role in protein metabolism, gene expression, chromatin structure, and photosynthetic carbon metabolism [51]. In addition, it is associated with the stabilizing and protective effect on biomembranes against oxidative and peroxidative damage, loss of plasma membrane integrity, and alteration of the permeability of the membrane [52,53].…”

Proteomics of heavy metal toxicity in plants

“…However, proteomic studies of metal stress have been far less numerous and comprehensive in comparison with investigations regarding other environmental stresses in plants (30). Although the processes of heavy metal uptake, accumulation, distribution, oxidative stress induction, and detoxification have been investigated in a wide range of studies on plants (47)(48)(49)(50)(51)(52)(53)(54), the mechanisms involved are still only partially understood. The proteomic approach can therefore help to elucidate new aspects of plant metal stress.…”

Growth and photosynthetic responses of Lemna minor L. exposed to cadmium in combination with zinc or copper / Rast i fotosinteza u vodene leće (Lemna minor L.) izložene kadmiju u kombinaciji s cinkom ili bakrom

“…Data sets used for PCA were comprised of 10 variables including growth, Cd, Zn, and Cu accumulation, Chl a,Chl b, total chlorophylls and carotenoid content, maximum quantum yield (F v /F m ) and effective quantum yield (∆F/F' m ). Also, malondialdehyde (MDA) content, reported previously (31,32), was added as a variable representing oxidative stress parameter. PCA was applied to the standardised data set and the factor loadings were classified as "strong", "moderate", and "weak" corresponding to absolute loading values of >0.75, 0.75-0.50, and 0.50-0.30, respectively (42).…”

“…Cd inhibits Chl biosynthesis through δ-aminolevulinic acid dehydratase and protochlorophyllide reductase due to interaction with -SH groups which leads to a diminished production of δ-aminolevulinic acid -the first common precursor for all tetrapyrroles (29). The observed effect of CdCl 2 on pigments could partly be caused by Cd-induced oxidative stress (31). Contrary to redox active metals, Cd is involved in the production of ROS indirectly -by interactions with antioxidative defence system, substitution of essential elements at enzyme active sites, and disruption of electron transport chain (29,50).…”

“…In our previous studies (31,32) we investigated the effect of Cd on the induction of oxidative stress and DNA damage in duckweed (L. minor L.), a rapidly growing aquatic monocotyledon commonly used in ecotoxicological studies (33). To further elucidate the effects of Cd (5 µmol L ) on photosynthetic features, the present work evaluated growth, chlorophyll and carotenoid content as well as photosynthetic efficiency by chlorophyll fluorescence.…”