Assessing the difference of tolerance and phytoremediation potential in mercury contaminated soil of a non-food energy crop, Helianthus tuberosus L. (Jerusalem artichoke)

Abstract

This study was conducted to evaluate the effects of mercury stress on growth, photosynthesis and mercury accumulation in different cultivars of a non-food energy crop, Jerusalem artichoke, and to screen appropriate cultivars for their efficacy in the phytoremediation of mercury (Hg2+) contaminated soil. Cultivars LZJ033 (high above-ground biomass and nutrient content, and strongly sexual reproduction) and LZJ119 (a long period of vegetative growth) exhibited more tolerance to mercury stress than LZJ047 (the highest tuber yield and total sugar content). The lines LZJ119 and LZJ047 showed delays in emergence time of about four weeks, and LZJ047 exhibited the highest mortality rate, 85.19%, under treatment with 10 mg kg-1 mercury. The MDA (malondialdehyde) content increased whereas and the Pn (net photosynthetic rate), Fv∕Fm (the maximum quantum yield of PSII photochemistry) and chlorophyll content decreased in response to mercury stress. The stem diameter, stem biomass and photosynthetic rate of Jerusalem artichoke showed some modest increases in response to mercury stress and exhibited hormesis at least 1 mg kg-1 mercury treatment. Overall, LZJ119 produced more biomass under mercury stress, whereas LZJ033 exhibited a greater capacity for mercury bioaccumulation. Accordingly, LZJ119 may be a good candidate cultivar for use in cases of moderate—low mercury contamination, whereas LZJ033 may be a better candidate under conditions of high mercury contamination. When Jerusalem artichoke was cultivated in mercury contaminated soil, it not only removed the mercury from soil but also produced large amounts of tubers and shoots which could be used as feedstock for the production of bioethanol.

The Role of Heavy Metals in Plant Response to Biotic Stress

“…Besides, numerous experiments with chromium (Cr) revealed hormetic growth in the cases of Eichhornia crassipes [ 67 ], Salsola kali L. [ 68 ], Lemna minuta [ 69 ], Allium cepa L. [ 70 ] and Capsicium annum L. [ 71 ]. An hormetic response was observed as well, in the case of elements such as lanthanum (La) for Lonicera japonica [ 72 ], Oryza sativa L. [ 73 ] and Arabis paniculata [ 66 ], Pb for Pisum sativum [ 35 ], Brassica pekinensis [ 74 ] and Dianthus carthusianorum [ 60 ], Hg for Anthyllis vulneraria [ 75 ] and Helianthus tuberosus [ 76 ], palladium (Pd) for P. sativum L. [ 77 ], platinum (Pt) for Arabidopsis thaliana [ 78 ], uranium (U) for Schizachyrium scoparium [ 79 ], Zn for Thlaspi caerulescens [ 80 ], Sedum alfredii [ 57 ] and Arabis paniculata [ 66 ].…”

The Toxicity of Mercury and Its Chemical Compounds: Molecular Mechanisms and Environmental and Human Health Implications: A Comprehensive Review

“…Hg 0 has a limited affinity toward cellular ligands and can only be harmful upon the oxidation to Hg 2+ inside the cell. The Hg-induced plant toxicity is defined as suppressing plant growth as well as the yield of biomass production, 191 negatively impact the efficacy of the photosynthetic process, 192 deficiency of nutrients, 193 oxidative stress, 194 genotoxicity, 195 and peroxidation of lipids. 196 Hg 2+ ions have a great affinity toward sulfur-containing groups, disrupting practically every activity involving essential or nonprotected proteins.…”

Roles and significance of chelating agents for potentially toxic elements (PTEs) phytoremediation in soil: A review

“…PTEs can be switched from a toxic state to a non-toxic or low-toxic state through phytostabilisation (Li et al, 2019;Sharma and Pandey, 2014). Besides, the plant root exudates have stabilised and demobilised the toxic elements, thus preventing the movement of PTEs around the rhizosphere area of the plant (Lv et al, 2018;Van Oosten and Maggio, 2014). As the PTEs are absorbed and attached to the rhizosphere parts of the plants, it decreases the bioavailability of these elements (Ali et al, 2013).…”