The Response of Duckweed (Lemna minor L.) Roots to Cd and Its Chemical Forms

Yan Xue,Jin Huang,Ming Wang,Jin-Qin Wang,Feng-Ying Li

doi:10.1155/2018/7274020

Yan Xue, Jin Huang + Show 3 more

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https://doi.org/10.1155/2018/7274020

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Abstract

The response of duckweed (Lemna minor L.) roots to Cd and its chemical forms was investigated. The relative root growth rate and concentrations of Cd and its different chemical forms in the root, that is, ethanol-extractable (FE-Cd), HCl-extractable (FHCl-Cd), and residual fractions (Fr-Cd), were quantified. Weibull model was used to unravel the regression between the relative root elongation (RRL) with chemical forms of Cd. Parameters assessed catalase (CAT), peroxidases (POD), and superoxide dismutase (SOD), as well as malondialdehyde (MDA) and total antioxidant capacity (A-TOC). Our results show that both the relative root growth rate and relative frond number were affected by Cd concentrations. The chemical forms of Cd were influenced by Cd content in the medium. Relative root elongation (RRL) showed a significant correlation with chemical forms of Cd. Additionally, POD and SOD increased at lower Cd concentrations followed by a decrease at higher Cd concentrations (at more than 5 μM Cd). Moreover, MDA and A-TOC increased and CAT decreased with increasing Cd exposure. Furthermore, CAT showed a significant correlation with FHCl-Cd. Taken together, it can be concluded that the chemical forms of Cd are statistically significant predictors of Cd toxicity to duckweed and to the other similar aquatic plants.

Highlights

Cadmium (Cd) is a major contributor to heavy metal pollution
The relative root growth rate showed a continuous decrease with an increase of exposed Cd concentrations from 0.1 μM to 20 μM
The response of duckweed roots to Cd stress is accompanied by changes in intracellular biological processes, including antioxidant enzymatic activity and the production of different chemical forms of Cd

Summary

Introduction

Cadmium (Cd) is a major contributor to heavy metal pollution. It is found in both natural and waste waters and is produced by agriculture through pesticides and fertilizers use and wastewater irrigation and by industry through smelting, metalworking, and pigmentation [1, 2]. The metal has a relatively high solubility and mobility in water and is absorbed for aquatic plants [3]. It destroys photosynthetic apparatus and carbohydrate metabolisms of plants [3,4,5] and can be transferred in the food chain to threat human health [6]. Plants have developed several detoxification mechanisms to alleviate Cd toxicity, including the existence of different forms of metals and sequestration into the cell wall [8, 9]

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