1
|
Lee H, Nguyen DV, Wu D, De Saeger J, Park M, Lee SD, Yu Y, Lee J, Lee C, Han T, Park J. A rapid and multi-endpoint ecotoxicological test using Mychonastes afer for efficient screening of metals and herbicides. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2024; 281:116652. [PMID: 38941657 DOI: 10.1016/j.ecoenv.2024.116652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2024] [Revised: 06/22/2024] [Accepted: 06/26/2024] [Indexed: 06/30/2024]
Abstract
Microalgal growth-based tests are international standards for ecotoxicity assessment; however, their long exposure times, large sample volumes, and reliance on a single growth-endpoint make them inadequate for rapid toxicity screening. Here, we aimed to develop a rapid and simple ecotoxicological test using the fast-growing green alga Mychonastes afer, with multiple endpoints-growth, lipid content, and photosynthesis. We exposed M. afer to two metals-silver and copper-and two herbicides-atrazine and diuron-for 24 h and identified the most sensitive and reliable endpoints for each toxicant: the maximum electron transport rate (ETRmax) for Ag, Cu and atrazine, and the lipid content for diuron. Lipid content was found to be both a sensitive and reliable biomarker, meeting the effluent limit guidelines in both the Republic of Korea and the USA. The sensitivity of M. afer to Ag and atrazine also closely matched the HC5 values derived from the species sensitivity distribution approach, confirming its reliability for setting regulatory concentrations of these contaminants. Our calculated predicted no-effect concentration (PNEC) values were similar to established European Union PNECs for Ag, Cu, atrazine, and diuron, underlining the utility of these biological endpoints for ecological risk assessment and regulatory decision making. This method required lower sample volume (2 mL vs 100 mL) and exposure time (24 h vs 72-120 h) than conventional green algal tests, and eliminated the need for labour-intensive cell counting, expensive equipment, and chlorophyll fluorescence measurement expertise. Overall, this M. afer test can be a valuable tool for the rapid screening of wastewater for metals and herbicides, contributing to environmental protection and management practices.
Collapse
Affiliation(s)
- Hojun Lee
- Bio Environmental Science and Technology (BEST) Lab, Ghent University Global Campus, 119-5, Songdomunhwa-ro, Incheon 21985, Republic of Korea
| | - Duc-Viet Nguyen
- Center for Environmental and Energy Research, Ghent University Global Campus, 119-5, Songdomunhwa-ro, Incheon 21985, Republic of Korea
| | - Di Wu
- Center for Environmental and Energy Research, Ghent University Global Campus, 119-5, Songdomunhwa-ro, Incheon 21985, Republic of Korea
| | - Jonas De Saeger
- Bio Environmental Science and Technology (BEST) Lab, Ghent University Global Campus, 119-5, Songdomunhwa-ro, Incheon 21985, Republic of Korea
| | - Mirye Park
- Protist Research Team, Microbial Research Department, Nakdonggang National Institute of Biological Resources, 137, Donam-2-gil, Sangju-si, Gyeongsangbuk-do 37242, Republic of Korea
| | - Sang Deuk Lee
- Protist Research Team, Microbial Research Department, Nakdonggang National Institute of Biological Resources, 137, Donam-2-gil, Sangju-si, Gyeongsangbuk-do 37242, Republic of Korea
| | - Youngseock Yu
- Bio Environmental Science and Technology (BEST) Lab, Ghent University Global Campus, 119-5, Songdomunhwa-ro, Incheon 21985, Republic of Korea
| | - Jaeyoung Lee
- Bio Environmental Science and Technology (BEST) Lab, Ghent University Global Campus, 119-5, Songdomunhwa-ro, Incheon 21985, Republic of Korea
| | - Chaeyeon Lee
- Bio Environmental Science and Technology (BEST) Lab, Ghent University Global Campus, 119-5, Songdomunhwa-ro, Incheon 21985, Republic of Korea
| | - Taejun Han
- Bio Environmental Science and Technology (BEST) Lab, Ghent University Global Campus, 119-5, Songdomunhwa-ro, Incheon 21985, Republic of Korea; Department of Animal Sciences and Aquatic Ecology, Ghent University, Coupure Links 653-Block F, Gent B-9000, Belgium
| | - Jihae Park
- Bio Environmental Science and Technology (BEST) Lab, Ghent University Global Campus, 119-5, Songdomunhwa-ro, Incheon 21985, Republic of Korea; Center for Environmental and Energy Research, Ghent University Global Campus, 119-5, Songdomunhwa-ro, Incheon 21985, Republic of Korea; Department of Animal Sciences and Aquatic Ecology, Ghent University, Coupure Links 653-Block F, Gent B-9000, Belgium.
| |
Collapse
|
2
|
Weber-Theen A, Dören L. Chronic toxicity of pharmaceuticals to the benthic green alga Closterium ehrenbergii. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2024; 272:116025. [PMID: 38290309 DOI: 10.1016/j.ecoenv.2024.116025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Revised: 12/30/2023] [Accepted: 01/24/2024] [Indexed: 02/01/2024]
Abstract
Pharmaceuticals in the environment have emerged to a topic of global concern. Since these substances are designed to be biologically active, hazardous effects on non-target organisms are frequently reported. Here, the effects of five pharmaceuticals, one radiocontrast agent, and one degradation product on the freshwater green alga Closterium ehrenbergii were evaluated after chronic exposure of 168 h. Growth and maximum quantum yield (FV/FM) were used as endpoints and complemented by the assessment of morphology and chlorophyll fluorescence. We found that the tested antibiotics Ciprofloxacin and Ofloxacin impaired chloroplast integrity, resulting in a reduction of FV/FM from 0.1 mg/L. The disintegration of chloroplasts at higher concentrations (c = 0.3 and 0.8 mg/L, respectively) was visualized by brightfield and fluorescence microscopy. In contrast, Sulfamethoxazole interfered with cell division, leading to malformation of cells from 0.8 mg/L. Furthermore, the antibiotics exhibited a latency period of 72 h after which they started to reveal their true effects. Therefore, the importance of long-term toxicity testing is outlined in order to avoid underestimation of toxic effects of pharmaceuticals. Based on the EC10 values obtained, the antibiotics were considered to meet the criteria for classification as toxic to aquatic life with long lasting effects. The other test substances were found to exert no effects on C. ehrenbergii or only at very high concentrations and were classified as nontoxic.
Collapse
Affiliation(s)
- Andreas Weber-Theen
- Department of Environmental Engineering, Laboratories of Ecotoxicology and Analytical Chemistry, RheinMain University of Applied Sciences, P.O. Box 3251, 65022 Wiesbaden, Germany; Department of Experimental Phycology and Culture Collection of Algae, Georg-August-University, Göttingen, Germany.
| | - László Dören
- Department of Environmental Engineering, Laboratories of Ecotoxicology and Analytical Chemistry, RheinMain University of Applied Sciences, P.O. Box 3251, 65022 Wiesbaden, Germany
| |
Collapse
|
3
|
Irfan M, Mészáros I, Szabó S, Oláh V. Comparative Phytotoxicity of Metallic Elements on Duckweed Lemna gibba L. Using Growth- and Chlorophyll Fluorescence Induction-Based Endpoints. PLANTS (BASEL, SWITZERLAND) 2024; 13:215. [PMID: 38256768 PMCID: PMC10821045 DOI: 10.3390/plants13020215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Revised: 01/06/2024] [Accepted: 01/07/2024] [Indexed: 01/24/2024]
Abstract
In this study, we exposed a commonly used duckweed species-Lemna gibba L.-to twelve environmentally relevant metals and metalloids under laboratory conditions. The phytotoxic effects were evaluated in a multi-well-plate-based experimental setup by means of the chlorophyll fluorescence imaging method. This technique allowed the simultaneous measuring of the growth and photosynthetic parameters in the same samples. The inhibition of relative growth rates (based on frond number and area) and photochemical efficiency (Fv/Fo and Y(II)) were both calculated from the obtained chlorophyll fluorescence images. In the applied test system, growth-inhibition-based phytotoxicity endpoints proved to be more sensitive than chlorophyll-fluorescence-based ones. Frond area growth inhibition was the most responsive parameter with a median EC50 of 1.75 mg L-1, while Fv/Fo, the more responsive chlorophyll-fluorescence-based endpoint, resulted in a 5.34 mg L-1 median EC50 for the tested metals. Ag (EC50 0.005-1.27 mg L-1), Hg (EC50 0.24-4.87 mg L-1) and Cu (EC50 0.37-1.86 mg L-1) were the most toxic elements among the tested ones, while As(V) (EC50 47.15-132.18 mg L-1), Cr(III) (EC50 6.22-19.92 mg L-1), Se(VI) (EC50 1.73-10.39 mg L-1) and Zn (EC50 3.88-350.56 mg L-1) were the least toxic ones. The results highlighted that multi-well-plate-based duckweed phytotoxicity assays may reduce space, time and sample volume requirements compared to the standard duckweed growth inhibition tests. These benefits, however, come with lowered test sensitivity. Our multi-well-plate-based test setup resulted in considerably higher median EC50 (3.21 mg L-1) for frond-number-based growth inhibition than the 0.683 mg L-1 median EC50 derived from corresponding data from the literature with standardized Lemna-tests. Under strong acute phytotoxicity, frond parts with impaired photochemical functionality may become undetectable by chlorophyll fluorometers. Consequently, the plant parts that are still detectable display a virtually higher average photosynthetic performance, leading to an underestimation of phytotoxicity. Nevertheless, multi-well-plate-based duckweed phytotoxicity assays, combined with chlorophyll fluorescence imaging, offer definite advantages in the rapid screening of large sample series or multiple species/clones. As chlorophyll fluorescence images provide information both on the photochemical performance of the test plants and their morphology, a joint analysis of the two endpoint groups is recommended in multi-well-plate-based duckweed phytotoxicity assays to maximize the information gained from the tests.
Collapse
Affiliation(s)
- Muhammad Irfan
- Department of Botany, Institute of Biology and Ecology, Faculty of Science and Technology, University of Debrecen, Egyetem Square 1, H-4032 Debrecen, Hungary; (M.I.); (I.M.)
| | - Ilona Mészáros
- Department of Botany, Institute of Biology and Ecology, Faculty of Science and Technology, University of Debrecen, Egyetem Square 1, H-4032 Debrecen, Hungary; (M.I.); (I.M.)
| | - Sándor Szabó
- Department of Biology, Institute of Environmental Sciences, University of Nyiregyhaza, H-4401 Nyiregyhaza, Hungary
| | - Viktor Oláh
- Department of Botany, Institute of Biology and Ecology, Faculty of Science and Technology, University of Debrecen, Egyetem Square 1, H-4032 Debrecen, Hungary; (M.I.); (I.M.)
| |
Collapse
|
4
|
Lee H, Kim G, Depuydt S, Shin K, Han T, Park J. Metal Toxicity across Different Thallus Sections of the Green Macroalga, Ulva australis. TOXICS 2023; 11:548. [PMID: 37505514 PMCID: PMC10384764 DOI: 10.3390/toxics11070548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2023] [Revised: 06/17/2023] [Accepted: 06/20/2023] [Indexed: 07/29/2023]
Abstract
We aimed to identify functional differences between different sections of the thallus of Ulva australis and develop tissue-endpoint combinations to assess the toxicity of six metals (i.e., Ag, As, Cd, Cr, Cu, and Ni). EC50 values for these metals in three sections of the thallus of Ulva were obtained for multiple endpoints: relative growth rate (RGR), chlorophyll a fluorescence, pigment contents, and the expression of the photosynthesis-related gene, rbcL. The responses of the endpoints varied across the respective thallus sections; overall, the most toxic metals were Ag and Cu. These endpoints were the best for evaluating metal toxicity: ETRmax of the middle thallus sections for Ag toxicity; RGR of the middle thallus section for As and Cd; ETRmax of the marginal thallus section for Cr; Chl b contents of the marginal thallus section for Cu; RGR of the basal thallus section for Ni. The EC50 values for the inhibition of ETRmax in middle (0.06 mg∙L-1) and Chl b in the marginal thallus sections (0.06 mg∙L-1) were all lower than those of the quality standard for wastewater discharge values of Ag and Cu in Republic of Korea and the US, pointing to the suitability of U. australis-based endpoints for risk assessment.
Collapse
Affiliation(s)
- Hojun Lee
- Bio Environmental Science and Technology (BEST) Lab, Ghent University Global Campus, 119-5, Songdomunhwa-ro, Incheon 21985, Republic of Korea
| | - Geonhee Kim
- Department of Marine Science, Incheon National University, 119, Academy-ro, Yeonsu-gu, Incheon 22012, Republic of Korea
| | - Stephen Depuydt
- Erasmus Brussels University of Applied Sciences and Arts, Nijverheidskaai 170, 1070 Brussels, Belgium
| | - Kisik Shin
- Water Environmental Engineering Research Division, National Institute of Environmental Research (NIER), 42, Hwangyeong-ro, Incheon 22689, Republic of Korea
| | - Taejun Han
- Bio Environmental Science and Technology (BEST) Lab, Ghent University Global Campus, 119-5, Songdomunhwa-ro, Incheon 21985, Republic of Korea
- Department of Animal Sciences and Aquatic Ecology, Ghent University, Coupure Links 653-Block F, B-9000 Gent, Belgium
| | - Jihae Park
- Department of Animal Sciences and Aquatic Ecology, Ghent University, Coupure Links 653-Block F, B-9000 Gent, Belgium
- Centre for Environmental and Energy Research, Ghent University Global Campus, 119-5, Songdomunhwa-ro, Incheon 21985, Republic of Korea
| |
Collapse
|
5
|
Metabolomics-Based Mechanistic Insights into Revealing the Adverse Effects of Pesticides on Plants: An Interactive Review. Metabolites 2023; 13:metabo13020246. [PMID: 36837865 PMCID: PMC9958811 DOI: 10.3390/metabo13020246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 01/30/2023] [Accepted: 02/06/2023] [Indexed: 02/11/2023] Open
Abstract
In plant biology, metabolomics is often used to quantitatively assess small molecules, metabolites, and their intermediates in plants. Metabolomics has frequently been applied to detect metabolic alterations in plants exposed to various biotic and abiotic stresses, including pesticides. The widespread use of pesticides and agrochemicals in intensive crop production systems is a serious threat to the functionality and sustainability of agroecosystems. Pesticide accumulation in soil may disrupt soil-plant relationships, thereby posing a pollution risk to agricultural output. Application of metabolomic techniques in the assessment of the biological consequences of pesticides at the molecular level has emerged as a crucial technique in exposome investigations. State-of-the-art metabolomic approaches such as GC-MS, LC-MS/MS UHPLC, UPLC-IMS-QToF, GC/EI/MS, MALDI-TOF MS, and 1H-HR-MAS NMR, etc., investigating the harmful effects of agricultural pesticides have been reviewed. This updated review seeks to outline the key uses of metabolomics related to the evaluation of the toxicological impacts of pesticides on agronomically important crops in exposome assays as well as bench-scale studies. Overall, this review describes the potential uses of metabolomics as a method for evaluating the safety of agricultural chemicals for regulatory applications. Additionally, the most recent developments in metabolomic tools applied to pesticide toxicology and also the difficulties in utilizing this approach are discussed.
Collapse
|
6
|
Van Antro M, Prelovsek S, Ivanovic S, Gawehns F, Wagemaker NCAM, Mysara M, Horemans N, Vergeer P, Verhoeven KJF. DNA methylation in clonal duckweed (Lemna minor L.) lineages reflects current and historical environmental exposures. Mol Ecol 2023; 32:428-443. [PMID: 36324253 PMCID: PMC10100429 DOI: 10.1111/mec.16757] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 09/16/2022] [Accepted: 10/11/2022] [Indexed: 11/06/2022]
Abstract
Environmentally induced DNA methylation variants may mediate gene expression responses to environmental changes. If such induced variants are transgenerationally stable, there is potential for expression responses to persist over multiple generations. Our current knowledge in plants, however, is almost exclusively based on studies conducted in sexually reproducing species where the majority of DNA methylation changes are subject to resetting in germlines, limiting the potential for transgenerational epigenetics stress memory. Asexual reproduction circumvents germlines, and may therefore be more conducive to long-term inheritance of epigenetic marks. Taking advantage of the rapid clonal reproduction of the common duckweed Lemna minor, we hypothesize that long-term, transgenerational stress memory from exposure to high temperature can be detected in DNA methylation profiles. Using a reduced representation bisulphite sequencing approach (epiGBS), we show that temperature stress induces DNA hypermethylation at many CG and CHG cytosine contexts but not CHH. Additionally, differential methylation in CHG context that was observed was still detected in a subset of cytosines, even after 3-12 generations of culturing in a common environment. This demonstrates a memory effect of stress reflected in the methylome and that persists over multiple clonal generations. Structural annotation revealed that this memory effect in CHG methylation was enriched in transposable elements. The observed epigenetic stress memory is probably caused by stable transgenerational persistence of temperature-induced DNA methylation variants across clonal generations. To the extent that such epigenetic memory has functional consequences for gene expression and phenotypes, this result suggests potential for long-term modulation of stress responses in asexual plants.
Collapse
Affiliation(s)
- Morgane Van Antro
- Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands
| | - Stella Prelovsek
- Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands
| | - Slavica Ivanovic
- Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands
| | - Fleur Gawehns
- Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands
| | | | - Mohamed Mysara
- Biosphere Impact Studies, Belgian Nuclear Research Centre (SCK CEN), Mol, Belgium
| | - Nele Horemans
- Biosphere Impact Studies, Belgian Nuclear Research Centre (SCK CEN), Mol, Belgium
| | - Philippine Vergeer
- Plant Ecology and Physiology, Radboud University, Nijmegen, The Netherlands.,Wageningen University and Research (WUR), Plant Ecology and Nature Conservation Group, Wageningen, The Netherlands
| | - Koen J F Verhoeven
- Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands
| |
Collapse
|
7
|
Clay-Catalyzed Ozonation of Organic Pollutants in Water and Toxicity on Lemna minor: Effects of Molecular Structure and Interactions. Molecules 2022; 28:molecules28010222. [PMID: 36615416 PMCID: PMC9822386 DOI: 10.3390/molecules28010222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 12/12/2022] [Accepted: 12/16/2022] [Indexed: 12/28/2022] Open
Abstract
The use of clays as adsorbents and catalysts in the ozonation of organic pollutants (Atrazine, bis-Phenol A, Diazinon, and Diclofenac sodium) allowed simulating their natural oxidative degradation in clay soils and to evaluate the ecotoxicity of mixtures partially oxidized on the species Lemna minor, a biodiversity representative of plants in the aquatic environment. Kinetic data showed that the adsorption of organic pollutants on clay particles obeys the pseudo-second-order model, while the adsorption isotherms satisfactorily fit the Langmuir model. Adsorption reduces the dispersion of the organic pollutant in the environment and prolongs its persistence and its natural degradation probability. Measurements of the Zeta potential and particle size as a function of pH demonstrate that the catalytic activity of clay depends on its cation, its silica/alumina ratio, and therefore on its permanent and temporary ion exchange capacities. These factors seem to govern its delamination and dispersion in aqueous media, its hydrophilic-hydrophobic character, and its porosity. Tests conducted on Lemna minor in contact with ozonation mixtures revealed that the toxicity could be due to pH decrease and to the toxicity of the intermediates yielded. Ecotoxicity would depend on the structure of the organic molecules, the chemical composition of the clay surface and ozonation time, which determines the oxidation progress. These results are of great importance for further research because they allow concluding that the negative impact of the persistence of an organic molecule in clay-containing media depends on the type and composition of the very clay mineral.
Collapse
|
8
|
Wang XD, Zhang CY, Yuan Y, Hua YF, Asami T, Qin Y, Xiong XH, Zhu JL, Lu YC. Molecular Responses and Degradation Mechanisms of the Herbicide Diuron in Rice Crops. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2022; 70:14352-14366. [PMID: 36326728 DOI: 10.1021/acs.jafc.2c05142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Diuron [DU; 3-(3,4-dichlorophenyl)-1,1-dimethylurea], a widely used herbicide for weed control, arouses ecological and health risks due to its environment persistence. Our findings revealed that DU at 0.125-2.0 mg L-1 caused oxidative damage to rice. RNA-sequencing profiles disclosed a globally genetic expression landscape of rice under DU treatment. DU mediated downregulated gene encoding photosynthesis and biosynthesis of protein, fatty acid, and carbohydrate. Conversely, it induced the upregulation of numerous genes involved in xenobiotic metabolism, detoxification, and anti-oxidation. Furthermore, 15 DU metabolites produced by metabolic genes were identified, 7 of which include two Phase I-based and 5 Phase II-based derivatives, were reported for the first time. The changes of resistance-related phytohormones, like JA, ABA, and SA, in terms of their contents and molecular-regulated signaling pathways positively responded to DU stress. Our work provides a molecular-scale perspective on the response of rice to DU toxicity and clarifies the biotransformation and degradation fate of DU in rice crops.
Collapse
Affiliation(s)
- Xiao Dong Wang
- College of Food Science and Light Industry, Nanjing Tech University, Nanjing211816, China
| | - Chen Yi Zhang
- College of Food Science and Light Industry, Nanjing Tech University, Nanjing211816, China
| | - Yi Yuan
- Horticultural Research Institute, Yunnan Academy of Agricultural Sciences, Kunming650205, China
| | - Yi Fei Hua
- College of Food Science and Light Industry, Nanjing Tech University, Nanjing211816, China
| | - Tadao Asami
- Department of Applied Biological Chemistry, The University of Tokyo, 1-1-1 Yayoi, Bunkyo, Tokyo113-8657, Japan
| | - Yi Qin
- College of Food Science and Light Industry, Nanjing Tech University, Nanjing211816, China
| | - Xiao Hui Xiong
- College of Food Science and Light Industry, Nanjing Tech University, Nanjing211816, China
| | - Jian Liang Zhu
- College of Food Science and Light Industry, Nanjing Tech University, Nanjing211816, China
| | - Yi Chen Lu
- College of Food Science and Light Industry, Nanjing Tech University, Nanjing211816, China
| |
Collapse
|
9
|
Oláh V, Hepp A, Irfan M, Mészáros I. Chlorophyll Fluorescence Imaging-Based Duckweed Phenotyping to Assess Acute Phytotoxic Effects. PLANTS (BASEL, SWITZERLAND) 2021; 10:2763. [PMID: 34961232 PMCID: PMC8707530 DOI: 10.3390/plants10122763] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2021] [Revised: 12/02/2021] [Accepted: 12/09/2021] [Indexed: 06/12/2023]
Abstract
Duckweeds (Lemnaceae species) are extensively used models in ecotoxicology, and chlorophyll fluorescence imaging offers a sensitive and high throughput platform for phytotoxicity assays with these tiny plants. However, the vast number of potentially applicable chlorophyll fluorescence-based test endpoints makes comparison and generalization of results hard among different studies. The present study aimed to jointly measure and compare the sensitivity of various chlorophyll fluorescence parameters in Spirodela polyrhiza (giant duckweed) plants exposed to nickel, chromate (hexavalent chromium) and sodium chloride for 72 h, respectively. The photochemistry of Photosystem II in both dark- and light-adapted states of plants was assessed via in vivo chlorophyll fluorescence imaging method. Our results indicated that the studied parameters responded with very divergent sensitivity, highlighting the importance of parallelly assessing several chlorophyll fluorescence parameters. Generally, the light-adapted parameters were more sensitive than the dark-adapted ones. Thus, the former ones might be the preferred endpoints in phytotoxicity assays. Fv/Fm, i.e., the most extensively reported parameter literature-wise, proved to be the least sensitive endpoint; therefore, future studies might also consider reporting Fv/Fo, as its more responsive analogue. The tested toxicants induced different trends in the basic chlorophyll fluorescence parameters and, at least partly, in relative proportions of different quenching processes, suggesting that a basic distinction of water pollutants with different modes of action might be achievable by this method. We found definite hormetic patterns in responses to several endpoints. Hormesis occurred in the concentration ranges where the applied toxicants resulted in strong growth inhibition in longer-term exposures of the same duckweed clone in previous studies. These findings indicate that changes in the photochemical efficiency of plants do not necessarily go hand in hand with growth responses, and care should be taken when one exclusively interprets chlorophyll fluorescence-based endpoints as general proxies for phytotoxic effects.
Collapse
Affiliation(s)
- Viktor Oláh
- Department of Botany, Faculty of Science and Technology, University of Debrecen, Egyetem tér 1, H-4032 Debrecen, Hungary; (A.H.); (M.I.); (I.M.)
| | | | | | | |
Collapse
|