Trace elements and activity of antioxidative enzymes in Cistus ladanifer L. growing on an abandoned mine area

Abstract

The Mediterranean shrub Cistus ladanifer grows naturally in São Domingos (Portugal), an abandoned copper mine. High levels of trace elements in plants can generate oxidative stress increasing the activity of antioxidant enzymes. The aim of this work was to evaluate and compare As, Cu, Pb and Zn concentrations and the activity of the soluble and cell wall ionically bounded forms of the enzymes catalase, peroxidase and superoxide dismutase in leaves of C. ladanifer, collected in spring and summer, growing on São Domingos mine and on a non-contaminated area (Pomarão). São Domingos soils showed high total concentrations of As (2.6 g kg(-1)) and Pb (7.3 g kg(-1)) however the available fraction represented less than 1.5% of the total. C. ladanifer population from mine showed tolerance to Pb and Zn, which attain in leaves concentrations considered toxic for plants. The enzymatic activity of catalase, peroxidise and superoxide dismutase varied with plant populations and seasons, although with no particular trend, being specific to each trace element and enzyme cell localization. Catalase activity was evenly distributed between the soluble and ionically bounded forms, whereas the ionically bounded form of peroxidase predominated relatively to total activity, and the opposite was observed for superoxide dismutase. Spring and summer leaves from the two areas presented enzymatic activities in both fractions except to peroxidase soluble activities in leaves collected in summer. C. ladanifer enzymatic activity seems to be related with the co-existence of different stress factors (trace elements concentration, temperature, UV radiation and drought). The survival and growth of this species on contaminated mining soils is due to the presence of effective antioxidant enzyme-based defence systems.

Pioneer Mediterranean Shrub Species Revegetating Soils Developed on Mining Soils/Spoils

“…In the same geographical area, plants in the studied soils/spoils with high total concentrations of As, Cu and Pb did not exhibit inhibition in their growth when compared with plants growing on non-contaminated soils (Abreu et al, 2009b;Abreu et al, 2009a;Abreu et al, 2011). This observation is in accordance with studies on plants belonging to species growing on contaminated and non-contaminated soils (Conesa et al, 2006;Abreu et al, 2009b;Santos et al, 2009;Wahsha et al, 2012). Arsenic concentration (the geometric mean of all samples leaves is 6·1 mg kg À1 ), in the majority of the plant species, for both young and mature leaves (Table IV), which was below the concentrations obtained in a uncontaminated area, the Pomarão area, not very far from São Domingos mining area (15-16 mg kg À1 ; Abreu et al, 2009b).…”

“…Kardanpour et al (2015) address heterogeneity of contaminated soils describing sampling as an essential step to have representative concentrations. Several examples of spontaneous and even new species of plants that grow on these degraded and contaminated soils/spoils are known (Batista et al, 2007;Mendez et al, 2007;Abreu et al, 2008Abreu et al, , 2012aAbreu et al, , 2012bReglero et al, 2008;Abreu & Magalhães, 2009;Santos et al, 2009). The plants that survive in such contaminated environments show, in general, no symptoms of toxicity.…”

Cistus salviifolius a promising species for mine wastes remediation

“…Trace elements concentrations in São Domingos soils are in the same range of other results reported for São Domingos mine (Freitas et al, 2009;Santos et al, 2009;Tavares et al, 2008). In São Domingos soils total concentrations of arsenic, antimony and lead seem to be related (r N 0.92).…”

“…This tolerance is due to the development of one or various biological, chemical or physiological adaptations. Reduction of trace elements uptake, accumulation in roots and the consequent reduction of the translocation to shoots, re-mobilization of trace elements to mature or senescent leaves, and activity of antioxidative enzymes are some tolerance mechanisms observed in plants growing in mining areas (Freitas et al, 2009;Murciego et al, 2007;Oliva et al, 2009;Santos et al, 2009). The natural succession of plants in mining areas can constitute distinctive metal/metalloid-tolerant communities (ecotypes) which have usually low diversity.…”

Cistus monspeliensis L. as a potential species for rehabilitation of soils with multielemental contamination under Mediterranean conditions

“…Also, the establishment of a self-sustaining vegetation, principally with pioneer species, contributes to the ecological succession. In general, several Cistus species growing in soils developed on mine wastes from the IPB present adequate ecological behaviours to the rehabilitation of these materials (Abreu et al 2012a , b ; Batista et al 2017 ; Alvarenga et al 2004 ; Freitas et al 2004 ; Santos et al 2009 , 2012 , 2014 ).…”