Response of Zea mays to multimetal contaminated soils: a multibiomarker approach

Abstract

Heavy metals present in mine tailings pollute agroecosystems, put the integrity of the environment at risk and become a major route of exposure to humans. The present study was carried out in Taxco, Guerrero, Mexico, where millions of tons of mine tailings have been deposited. Soils from this region are used for agricultural activities. Maize (Zea mays) was selected as a test plant, because it is one of the most common and important cereal crops in Mexico and worldwide. Thirteen metals were selected and their bioaccumulation in roots, leaves and fruits were measured in plants cultivated in soils contaminated with mine tailings and those cultivated in non-contaminated soils. The effect of metal bioaccumulation on: macro and micromorphology, size, biomass, coloration leaf patterns and on DNA damage levels in different structures were determined. The bioaccumulation pattern was: root > leaf > fruit, being only Mn and Cr bioaccumulated in all three structures and V in the roots and leaves. A significant effect of metal bioaccumulation on 50% of the size and leaf shape and 55% of the biomass characters in Z. mays exposed plants was detected. Regarding micromorphological characters, a significant effect of metal bioaccumulation on 67% of the leaf characters and on 100% of the color basal leaf characters was noted. The effect of metal bioaccumulation on the induction of DNA damage (leaf > fruit > root) was detected employing single cell gel electrophoresis analysis. An approach, in which multi endpoints are used is necessary to estimate the extent of the detrimental effects of metal pollution on agroecosystem integrity contaminated with mine tailings.

Bioaccumulation of heavy metals and As in maize (Zea mays L) grown close to mine tailings strongly impacts plant development

“…Wei et al (2020) found that most of the metals, such as Pb, Zn, Cr, and Mn, were mainly accumulated in the roots. Results show that in general, individuals exposed to multimetal contaminated soils were smaller, had altered leaf shape structures, and altered micromorphological characters (Ruiz-Huerta et al 2017;Tovar-Sánchez et al 2018;Kabata-Pendias 2000). All these data are consistent with the results obtained in this study.…”

“…Metal accumulation varies depending on the plant developmental stage as shown for 30 and 70 day maize plants (Ruiz and Armienta 2012). It is known that heavy metals affect signi cantly plant growth in maize, including roots, leaves, cobs, and stems (Wei et al 2020;Anjhum et al 2016;Tovar et al 2018). Additionally, Ruiz and Armienta, (2012) and Drlickova et al (2013) found that As is also harmful for maize growth.…”

“…Maize is an essential component of the Mexican diet and its harvest is an important economic activity for the peasant families. Frequently maize cultivation is located close to mine tailings, but the impact of contaminated soils on plant development is rarely studied even though it represents an important environmental issue with implications on human health along with social Maksimović et al 2007, Tovar-Sánchez et al 2018. Uptake and accumulation of high concentrations of heavy metals by a plant not only produce toxic symptoms and affect the metabolic processes, they also causes physiological, developmental, structural, and ultrastructural changes.…”

Phytoextraction of Zn(II) and Cu(II) by Canna indica: Related Physiological Effects

“…The use of such tools is currently increasing in the field of biomonitoring and bioremediation. Some biomarkers that have already been reported in plants are the following: oxidative stress by the production of reactive oxygen species [95], the reduction of macromorphological parameters such as plant height, stem diameter, and the number of leaves and negative modifications in chloroplasts with implications in photosynthesis [96]. These have been useful biomarkers for showing the adverse effects of metal exposition on the development, growth, and physiology of different plants exposed to this type of stress [97,98].…”

The Use of Biosensors for Biomonitoring Environmental Metal Pollution

“…Indeed, visible symptoms of heavy metal toxicity include chlorosis, leaf rolling and necrosis, senescence, wilting and stunted growth, low biomass production, limited numbers of seeds, and eventually death [58]. For example, reduction in morphological attributes of height, coverage, or biomass derived from exposure to HM has been reported in Arundo donax (Poaceae), exposed to As, Cd, and Pb [59]; Zea mays (Graminaceae) exposed to Cd, Fe, Ni, and Zn [60]; Prosopis laevigata (Fabaceae [61]), Pithecellobium dulce (Fabaceae [22]), Vachellia farnesiana (Fabaceae [21]), and Wigandia urens [23] exposed to Cu, Pb, and Zn.…”