Defense Mechanisms of Two Pioneer Submerged Plants during Their Optimal Performance Period in the Bioaccumulation of Lead: A Comparative Study.

Dian Li,Linglei Zhang,Min Chen,Jia Li,Xiaojia He,Ruidong An

doi:10.3390/ijerph15122844

Abstract

Ceratophyllum demersum L. and Hydrilla verticillata (L.f.) Royle, two pioneer, submerged plants, effectively remove heavy metals from contaminated water. The present work evaluates the bioaccumulation and defense mechanisms of these plants in the accumulation of lead from contaminated water during their optimal performance period. C. demersum and H. verticillata were investigated after 14 days of exposure to various lead concentrations (5–80 μM). The lead accumulation in both C. demersum and H. verticillata increased with an increasing lead concentration, reaching maximum values of 2462.7 and 1792 mg kg−1 dw, respectively, at 80 μM. The biomass and protein content decreased significantly in C. demersum when exposed to lead. The biomass of H. verticillata exposed to lead had no significant difference from that of the controls, and the protein content increased for the 5–10 μM exposure groups. The malondialdehyde (MDA) content and superoxide dismutase (SOD), peroxidase (POD), and polyphenol oxidase (PPO) activities were much higher in C. demersum, suggesting considerable damage from lipid peroxidation and sensitivity to lead stress. Enzyme inhibition and inactivation were also observed in C. demersum at high lead concentrations (40–80 μM). The excellent growth status, low damage from lipid peroxidation, and high activity of catalase (CAT) and phenylalanine ammonia-lyase (PAL) observed in H. verticillata illustrate its better tolerance under the same lead stress.

Highlights

As one of the major heavy metals, lead (Pb) has been an increasing concern for researchers because of its high toxicity, prevalent existence, persistence, and ubiquitous distribution [1]
This study explores the bioaccumulation and tolerance characteristics of C. demersum and H. verticillata during their optimal performance period and aims to determine which aquatic plant is a more efficient phytoremediator of Pb under various lead concentrations and how their defense mechanisms react to lead stress
The level of lead accumulation in both plant species continued to increase with the increasing lead concentration, and the maximum lead accumulation in

Summary

Introduction

As one of the major heavy metals, lead (Pb) has been an increasing concern for researchers because of its high toxicity, prevalent existence, persistence, and ubiquitous distribution [1]. Pb can have a negative impact on the morphology and growth status of plants [2], damage human health, and it does not have a beneficial effect on organisms [3]. More than 500 species of plants have been documented to have an excellent ability to absorb extremely high levels of heavy metals [7,8]. Aquatic macrophytes act as important primary producers in aquatic ecosystems and possess considerable accumulation ability. Submerged plants possess a higher ability for the removal of heavy metals from wastewater than floating-leaved plants and emerged plants because they have a greater surface area and more biomass for the heavy metal accumulation [6,9]

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Results

Conclusion