Copper and mercury induced oxidative stresses and antioxidant responses of Spirodela polyrhiza (L.) Schleid

Hanwant Singh,Deepak Kumar,Vineet Soni

doi:10.1016/j.bbrep.2020.100781

Hanwant Singh, Deepak Kumar + Show 1 more

Open Access

https://doi.org/10.1016/j.bbrep.2020.100781

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Abstract

Duckweed is recognized as a phytoremediation aquatic plant due to the production of large biomass and a high level of tolerance in stressed conditions. A laboratory experiment was conducted to investigate antioxidant response and mechanism of copper and mercury tolerance of S. polyrhiza (L.) Schleid. To understand the changes in chlorophyll content, MDA, proline, and activities of ROS-scavenging enzymes (SOD, CAT, GPOD) during the accumulation of Cu+2 and Hg+2, S. polyrhiza were exposed to various concentrations of Cu+2 (0.0–40 μM) and Hg+2 (0.0–0.4 μM). antioxidant activity initially indicated enhancing trend with application of 10 μM Cu+2; 0.2 μM Hg+2 (SOD), of 20 μM Cu+2; 0.2 μM Hg+2 (CAT) and of 10 μM Cu+2;0.2 μM Hg+2 (GPOD) and then decreased consistently up to 40 μM Cu+2 and 0.4 μM Hg+2. In the experiment chlorophyll and frond multiplication initially showed increasing tendency and decreased gradually with the application of increased metal concentration. Application of heavy metal has constantly enhanced proline and MDA content while the maximum increase was observed with the application of 40 μM Cu; 0.4 μM Hg for proline and MDA respectively. The upregulation of antioxidant enzymes and proline reveals that S. polyrhiza has strong biochemical strategies to deal with the heavy metal toxicity induced by the accumulation of Cu+2 and Hg+2.

Highlights

Numerous reports have shown that Heavy metals toxicity has become one of the major environmental threats [1] due to their adverse effects on plants, animals, and soil fertility [2]
Activities of superoxide peroxide (SOD), CAT, and Guaiacol peroxidase (GPOD) were determined in the fronds of S. polyrhiza
The present study found that Relative frond number (RFN) decreased with an increase in Cuþ2 and Hgþ2 concentration in the growth medium (Fig. 3a and b)

Summary

Introduction

Numerous reports have shown that Heavy metals toxicity has become one of the major environmental threats [1] due to their adverse effects on plants, animals, and soil fertility [2]. An excessive amount of heavy metal inside the plant cell can halt various cellular processes such as photosynthesis, respiration, biochemical processes, etc. Heavy metal stress can trigger increased production of ROS at a particular cellular compartment such as mitochondria, chloroplast, peroxisome, etc. The increased amount of ROS into the cell can induce oxidative stress and produce lipid peroxidation, ion leakage, DNA damage, and biomolecule degradation [12,13,14].

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