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Olsen P, Sha J, Fang Y, Chang C, Whiteside JH, Kinney S, Sues HD, Kent D, Schaller M, Vajda V. Arctic ice and the ecological rise of the dinosaurs. SCIENCE ADVANCES 2022; 8:eabo6342. [PMID: 35776799 PMCID: PMC10883366 DOI: 10.1126/sciadv.abo6342] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Abundant lake ice-rafted debris in Late Triassic and earliest Jurassic strata of the Junggar Basin of northwestern China (paleolatitude ~71°N) indicates that freezing winter temperatures typified the forested Arctic, despite a persistence of extremely high levels of atmospheric Pco2 (partial pressure of CO2). Phylogenetic bracket analysis shows that non-avian dinosaurs were primitively insulated, enabling them to access rich deciduous and evergreen Arctic vegetation, even under freezing winter conditions. Transient but intense volcanic winters associated with massive eruptions and lowered light levels led to the end-Triassic mass extinction (201.6 Ma) on land, decimating all medium- to large-sized nondinosaurian, noninsulated continental reptiles. In contrast, insulated dinosaurs were already well adapted to cold temperatures, and not only survived but also underwent a rapid adaptive radiation and ecological expansion in the Jurassic, taking over regions formerly dominated by large noninsulated reptiles.
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Affiliation(s)
- Paul Olsen
- Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10968, USA
| | - Jingeng Sha
- State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China
| | - Yanan Fang
- State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China
| | - Clara Chang
- Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10968, USA
| | - Jessica H Whiteside
- School of Ocean and Earth Sciences, National Oceanography Centre, University of Southampton, Southampton SO14 3ZH, UK
| | - Sean Kinney
- Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10968, USA
| | - Hans-Dieter Sues
- Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, DC 20013-7012, USA
| | - Dennis Kent
- Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10968, USA
- Earth and Planetary Sciences, Rutgers University, Piscataway, NJ 08854, USA
| | - Morgan Schaller
- Earth and Environmental Sciences, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
| | - Vivi Vajda
- Department of Palaeobiology, Swedish Museum of Natural History, Stockholm, Sweden
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2
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Hang H, Bauer M, Mio W, Mander L. Geometric and topological approaches to shape variation in Ginkgo leaves. ROYAL SOCIETY OPEN SCIENCE 2021; 8:210978. [PMID: 34849242 PMCID: PMC8611351 DOI: 10.1098/rsos.210978] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 10/25/2021] [Indexed: 05/09/2023]
Abstract
Leaf shape is a key plant trait that varies enormously. The range of applications for data on this trait requires frequent methodological development so that researchers have an up-to-date toolkit with which to quantify leaf shape. We generated a dataset of 468 leaves produced by Ginkgo biloba, and 24 fossil leaves produced by evolutionary relatives of extant Ginkgo. We quantified the shape of each leaf by developing a geometric method based on elastic curves and a topological method based on persistent homology. Our geometric method indicates that shape variation in modern leaves is dominated by leaf size, furrow depth and the angle of the two lobes at the leaf base that is also related to leaf width. Our topological method indicates that shape variation in modern leaves is dominated by leaf size and furrow depth. We have applied both methods to modern and fossil material: the methods are complementary, identifying similar primary patterns of variation, but also revealing different aspects of morphological variation. Our topological approach distinguishes long-shoot leaves from short-shoot leaves, both methods indicate that leaf shape influences or is at least related to leaf area, and both could be applied in palaeoclimatic and evolutionary studies of leaf shape.
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Affiliation(s)
- Haibin Hang
- Department of Mathematical Sciences, University of Delaware, Newark, DE 19716, USA
| | - Martin Bauer
- Department of Mathematics, Florida State University, Tallahassee, FL 32306, USA
| | - Washington Mio
- Department of Mathematics, Florida State University, Tallahassee, FL 32306, USA
| | - Luke Mander
- School of Environment, Earth and Ecosystem Sciences, The Open University, Milton Keynes, MK7 6AA, UK
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Khlebodarova TM, Likhoshvai VA. Causes of global extinctions in the history of life: facts and hypotheses. Vavilovskii Zhurnal Genet Selektsii 2020; 24:407-419. [PMID: 33659824 PMCID: PMC7716527 DOI: 10.18699/vj20.633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Paleontologists define global extinctions on Earth as a loss of about three-quarters of plant and animal species over a relatively short period of time. At least five global extinctions are documented in the Phanerozoic fossil record (~500-million-year period): ~65, 200, 260, 380, and 440 million years ago. In addition, there is evidence of global extinctions in earlier periods of life on Earth - during the Late Cambrian (~500 million years ago) and Ediacaran periods (more than 540 million years ago). There is still no common opinion on the causes of their occurrence. The current study is a systematized review of the data on recorded extinctions of complex life forms on Earth from the moment of their occurrence during the Ediacaran period to the modern period. The review discusses possible causes for mass extinctions in the light of the influence of abiogenic factors, planetary or astronomical, and the consequences of their actions. We evaluate the pros and cons of the hypothesis on the presence of periodicity in the extinction of Phanerozoic marine biota. Strong evidence that allows us to hypothesize that additional mechanisms associated with various internal biotic factors are responsible for the emergence of extinctions in the evolution of complex life forms is discussed. Developing the idea of the internal causes of periodicity and discontinuity in evolution, we propose our own original hypothesis, according to which the bistability phenomenon underlies the complex dynamics of the biota development, which is manifested in the form of global extinctions. The bistability phenomenon arises only in ecosystems with predominant sexual reproduction. Our hypothesis suggests that even in the absence of global abiotic catastrophes, extinctions of biota would occur anyway. However, our hypothesis does not exclude the possibility that in different periods of the Earth's history the biota was subjected to powerful external influences that had a significant impact on its further development, which is reflected in the Earth's fossil record.
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Affiliation(s)
- T M Khlebodarova
- Institute of Cytology and Genetics of Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
| | - V A Likhoshvai
- Institute of Cytology and Genetics of Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
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McElwain JC. Paleobotany and Global Change: Important Lessons for Species to Biomes from Vegetation Responses to Past Global Change. ANNUAL REVIEW OF PLANT BIOLOGY 2018; 69:761-787. [PMID: 29719166 DOI: 10.1146/annurev-arplant-042817-040405] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Human carbon use during the next century will lead to atmospheric carbon dioxide concentrations (pCO2) that have been unprecedented for the past 50-100+ million years according to fossil plant-based CO2 estimates. The paleobotanical record of plants offers key insights into vegetation responses to past global change, including suitable analogs for Earth's climatic future. Past global warming events have resulted in transient poleward migration at rates that are equivalent to the lowest climate velocities required for current taxa to keep pace with climate change. Paleobiome reconstructions suggest that the current tundra biome is the biome most threatened by global warming. The common occurrence of paleoforests at high polar latitudes when pCO2 was above 500 ppm suggests that the advance of woody shrub and tree taxa into tundra environments may be inevitable. Fossil pollen studies demonstrate the resilience of wet tropical forests to global change up to 700 ppm CO2, contrary to modeled predictions of the future. The paleobotanical record also demonstrates a high capacity for functional trait evolution as an additional strategy to migration and maintenance of a species' climate envelope in response to global change.
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Affiliation(s)
- Jennifer C McElwain
- Botany Department, Trinity College Dublin, The University of Dublin, Dublin 2, Ireland;
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5
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Haworth M, Belcher CM, Killi D, Dewhirst RA, Materassi A, Raschi A, Centritto M. Impaired photosynthesis and increased leaf construction costs may induce floral stress during episodes of global warming over macroevolutionary timescales. Sci Rep 2018; 8:6206. [PMID: 29670149 PMCID: PMC6049339 DOI: 10.1038/s41598-018-24459-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Accepted: 03/21/2018] [Indexed: 11/30/2022] Open
Abstract
Global warming events have coincided with turnover of plant species at intervals in Earth history. As mean global temperatures rise, the number, frequency and duration of heat-waves will increase. Ginkgo biloba was grown under controlled climatic conditions at two different day/night temperature regimes (25/20 °C and 35/30 °C) to investigate the impact of heat stress. Photosynthetic CO2-uptake and electron transport were reduced at the higher temperature, while rates of respiration were greater; suggesting that the carbon balance of the leaves was adversely affected. Stomatal conductance and the potential for evaporative cooling of the leaves was reduced at the higher temperature. Furthermore, the capacity of the leaves to dissipate excess energy was also reduced at 35/30 °C, indicating that photo-protective mechanisms were no longer functioning effectively. Leaf economics were adversely affected by heat stress, exhibiting an increase in leaf mass per area and leaf construction costs. This may be consistent with the selective pressures experienced by fossil Ginkgoales during intervals of global warming such as the Triassic - Jurassic boundary or Early Eocene Climatic Optimum. The physiological and morphological responses of the G. biloba leaves were closely interrelated; these relationships may be used to infer the leaf economics and photosynthetic/stress physiology of fossil plants.
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Affiliation(s)
- Matthew Haworth
- The Italian National Research Council - Tree and Timber Institute (CNR-IVALSA) Via Madonna del Piano 10, Sesto Fiorentino, 50019, Florence, Italy.
| | - Claire M Belcher
- University of Exeter wildFIRE Lab, Hatherly Labs Prince Wales Road Exeter, EX PS, Devon, England
| | - Dilek Killi
- Department of Agrifood Production and Environmental Sciences (DiSPAA), University of Florence Piazzale delle Cascine, 28 50144, Florence, Italy
| | - Rebecca A Dewhirst
- University of Exeter wildFIRE Lab, Hatherly Labs Prince Wales Road Exeter, EX PS, Devon, England
| | - Alessandro Materassi
- The Italian National Research Council - Institute of Biometeorology (CNR-IBIMET) Via Giovanni Caproni, 8 50145, Florence, Italy
| | - Antonio Raschi
- The Italian National Research Council - Institute of Biometeorology (CNR-IBIMET) Via Giovanni Caproni, 8 50145, Florence, Italy
| | - Mauro Centritto
- The Italian National Research Council - Tree and Timber Institute (CNR-IVALSA) Via Madonna del Piano 10, Sesto Fiorentino, 50019, Florence, Italy
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6
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Large-scale sill emplacement in Brazil as a trigger for the end-Triassic crisis. Sci Rep 2018; 8:141. [PMID: 29317730 PMCID: PMC5760721 DOI: 10.1038/s41598-017-18629-8] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Accepted: 12/13/2017] [Indexed: 11/20/2022] Open
Abstract
The end-Triassic is characterized by one of the largest mass extinctions in the Phanerozoic, coinciding with major carbon cycle perturbations and global warming. It has been suggested that the environmental crisis is linked to widespread sill intrusions during magmatism associated with the Central Atlantic Magmatic Province (CAMP). Sub-volcanic sills are abundant in two of the largest onshore sedimentary basins in Brazil, the Amazonas and Solimões basins, where they comprise up to 20% of the stratigraphy. These basins contain extensive deposits of carbonate and evaporite, in addition to organic-rich shales and major hydrocarbon reservoirs. Here we show that large scale volatile generation followed sill emplacement in these lithologies. Thermal modeling demonstrates that contact metamorphism in the two basins could have generated 88,000 Gt CO2. In order to constrain the timing of gas generation, zircon from two sills has been dated by the U-Pb CA-ID-TIMS method, resulting in 206Pb/238U dates of 201.477 ± 0.062 Ma and 201.470 ± 0.089 Ma. Our findings demonstrate synchronicity between the intrusive phase and the end-Triassic mass extinction, and provide a quantified degassing scenario for one of the most dramatic time periods in the history of Earth.
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Soh WK, Wright IJ, Bacon KL, Lenz TI, Steinthorsdottir M, Parnell AC, McElwain JC. Palaeo leaf economics reveal a shift in ecosystem function associated with the end-Triassic mass extinction event. NATURE PLANTS 2017; 3:17104. [PMID: 28714942 DOI: 10.1038/nplants.2017.104] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2016] [Accepted: 06/09/2017] [Indexed: 06/07/2023]
Abstract
Climate change is likely to have altered the ecological functioning of past ecosystems, and is likely to alter functioning in the future; however, the magnitude and direction of such changes are difficult to predict. Here we use a deep-time case study to evaluate the impact of a well-constrained CO2-induced global warming event on the ecological functioning of dominant plant communities. We use leaf mass per area (LMA), a widely used trait in modern plant ecology, to infer the palaeoecological strategy of fossil plant taxa. We show that palaeo-LMA can be inferred from fossil leaf cuticles based on a tight relationship between LMA and cuticle thickness observed among extant gymnosperms. Application of this new palaeo-LMA proxy to fossil gymnosperms from East Greenland reveals significant shifts in the dominant ecological strategies of vegetation found across the Triassic-Jurassic transition. Late Triassic forests, dominated by low-LMA taxa with inferred high transpiration rates and short leaf lifespans, were replaced in the Early Jurassic by forests dominated by high-LMA taxa that were likely to have slower metabolic rates. We suggest that extreme CO2-induced global warming selected for taxa with high LMA associated with a stress-tolerant strategy and that adaptive plasticity in leaf functional traits such as LMA contributed to post-warming ecological success.
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Affiliation(s)
- W K Soh
- School of Biology and Environmental Science, Earth Institute, University College Dublin, Belfield, Dublin 4, Ireland
| | - I J Wright
- Department of Biological Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
| | - K L Bacon
- School of Geography, University of Leeds, Leeds LS2 9JT, UK
| | - T I Lenz
- Department of Biological Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
| | - M Steinthorsdottir
- Department of Geological Sciences and Bolin Centre for Climate Research, Stockholm University, SE-109 61 Stockholm, Sweden
- Department of Paleobiology, Swedish Museum of Natural History, SE-104 05 Stockholm, Sweden
| | - A C Parnell
- School of Mathematics &Statistics, Insight Centre for Data Analytics, University College Dublin, Belfield, Dublin 4, Ireland
| | - J C McElwain
- School of Biology and Environmental Science, Earth Institute, University College Dublin, Belfield, Dublin 4, Ireland
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8
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McElwain JC, Steinthorsdottir M. Paleoecology, Ploidy, Paleoatmospheric Composition, and Developmental Biology: A Review of the Multiple Uses of Fossil Stomata. PLANT PHYSIOLOGY 2017; 174:650-664. [PMID: 28495890 PMCID: PMC5462064 DOI: 10.1104/pp.17.00204] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 05/10/2017] [Indexed: 05/05/2023]
Affiliation(s)
- Jennifer C McElwain
- Earth Institute, O'Brien Centre for Science, and School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland (J.C.M.);
- Department of Palaeobiology, Swedish Museum of Natural History, SE-104 05 Stockholm, Sweden (M.S.); and
- Bolin Centre for Climate Research, Stockholm University, SE-104 05 Stockholm, Sweden (M.S.)
| | - Margret Steinthorsdottir
- Earth Institute, O'Brien Centre for Science, and School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland (J.C.M.)
- Department of Palaeobiology, Swedish Museum of Natural History, SE-104 05 Stockholm, Sweden (M.S.); and
- Bolin Centre for Climate Research, Stockholm University, SE-104 05 Stockholm, Sweden (M.S.)
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9
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Li L, Xue M, Yi H. Uncovering microRNA-mediated response to SO2 stress in Arabidopsis thaliana by deep sequencing. JOURNAL OF HAZARDOUS MATERIALS 2016; 316:178-85. [PMID: 27232729 DOI: 10.1016/j.jhazmat.2016.05.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Revised: 04/24/2016] [Accepted: 05/04/2016] [Indexed: 05/20/2023]
Abstract
Sulfur dioxide (SO2) is a major air pollutant and has significant impacts on plants. MicroRNAs (miRNAs) are a class of gene expression regulators that play important roles in response to environmental stresses. In this study, deep sequencing was used for genome-wide identification of miRNAs and their expression profiles in response to SO2 stress in Arabidopsis thaliana shoots. A total of 27 conserved miRNAs and 5 novel miRNAs were found to be differentially expressed under SO2 stress. qRT-PCR analysis showed mostly negative correlation between miRNA accumulation and target gene mRNA abundance, suggesting regulatory roles of these miRNAs during SO2 exposure. The target genes of SO2-responsive miRNAs encode transcription factors and proteins that regulate auxin signaling and stress response, and the miRNAs-mediated suppression of these genes could improve plant resistance to SO2 stress. Promoter sequence analysis of genes encoding SO2-responsive miRNAs showed that stress-responsive and phytohormone-related cis-regulatory elements occurred frequently, providing additional evidence of the involvement of miRNAs in adaption to SO2 stress. This study represents a comprehensive expression profiling of SO2-responsive miRNAs in Arabidopsis and broads our perspective on the ubiquitous regulatory roles of miRNAs under stress conditions.
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Affiliation(s)
- Lihong Li
- School of Life Science, Shanxi University, Taiyuan, China
| | - Meizhao Xue
- School of Life Science, Shanxi University, Taiyuan, China
| | - Huilan Yi
- School of Life Science, Shanxi University, Taiyuan, China.
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10
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Wei A, Fu B, Wang Y, Zhai X, Xin X, Zhang C, Cao D, Zhang X. Involvement of NO and ROS in sulfur dioxide induced guard cells apoptosis in Tagetes erecta. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2015; 114:198-203. [PMID: 25645141 DOI: 10.1016/j.ecoenv.2015.01.024] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Revised: 01/21/2015] [Accepted: 01/22/2015] [Indexed: 06/04/2023]
Abstract
Both nitric oxide (NO) and reactive oxygen species (ROS) are very important signal molecules, but the roles they play in signal transduction of sulfur dioxide (SO2) induced toxicities on ornamental plants is not clear. In this study, the functions of NO and ROS in SO2-induced death of lower epidermal guard cells in ornamental plant Tagetes erecta were investigated. The results showed that SO2 derivatives (0.4-4.0 mmol L(-1) of final concentrations) could reduce the guard cells' viability and increase their death rates in a dose-dependent manner. Meanwhile, the significant increase of cellular NO, ROS, and Ca(2+) levels (P<0.05) and typical apoptosis features including nucleus condensation, nucleus break and nucleus fragmentation were observed. However, exposure to 2.0 mmol L(-1) of SO2 derivatives combined with either NO antagonists (NO scavenger c-PTIO; nitrate reductase inhibitor NaN3; NO synthase inhibitor L-NAME), ROS scavenger (AsA or CAT) or Ca(2+) antagonists (Ca(2+) scavenger EGTA or plasma membrane Ca(2+) channel blocker LaCl3) can effectively block SO2-induced guard cells death and corresponding increase of NO, ROS and Ca(2+) levels. In addition, addition of L-NAME or AsA in 2.0 mmol L(-1) of SO2 derivatives led to significant decrease in the levels of NO, ROS and Ca(2+), whereas addition of LaCl3 in them just resulted in the decrease of Ca(2+) levels, hardly making effects on NO and ROS levels. It was concluded that NO and ROS were involved in the apoptosis induced by SO2 in T. erecta, which regulated the cell apoptosis at the upstream of Ca(2+).
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Affiliation(s)
- Aili Wei
- Department of Biology, Taiyuan Normal University, Taiyuan 030031, China
| | - Baocun Fu
- Institute of Horticulture, Shanxi Academy of Agricultural Sciences, Taiyuan 030031, China.
| | - Yunshan Wang
- Institute of Horticulture, Shanxi Academy of Agricultural Sciences, Taiyuan 030031, China.
| | - Xiaoyan Zhai
- Department of Biology, Taiyuan Normal University, Taiyuan 030031, China.
| | - Xiaojing Xin
- Department of Plant Biology and Ecology, College of Life Science, Nankai University, Tianjin 300071, China.
| | - Chao Zhang
- Institute of Horticulture, Shanxi Academy of Agricultural Sciences, Taiyuan 030031, China.
| | - Dongmei Cao
- Institute of Horticulture, Shanxi Academy of Agricultural Sciences, Taiyuan 030031, China.
| | - Xiaobing Zhang
- Department of Biology, Taiyuan Normal University, Taiyuan 030031, China.
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Wei A, Fu B, Wang Y, Li R, Zhang C, Cao D, Zhang X, Duan J. The defense potential of glutathione-ascorbate dependent detoxification pathway to sulfur dioxide exposure in Tagetes erecta. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2015; 111:117-122. [PMID: 25450923 DOI: 10.1016/j.ecoenv.2014.10.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Revised: 09/17/2014] [Accepted: 10/06/2014] [Indexed: 06/04/2023]
Abstract
Sulfur dioxide (SO2) exposure is associated with increased risk of various damages to plants. However, little is known about the defense response in ornamental plants. In this study, an artificial fumigation protocol was carried out to study the defense potential of the glutathione (GSH)-ascorbate (AsA) dependent detoxification pathway to SO2 exposure in Tagetes erecta. The results show that when the plants were exposed to different doses of SO2 (0, 15, 30, 50 or 80 mg m(-3)) for different times (6, 12, 18, 24 or 33 h), SO2 induced oxidative stress was confirmed by the increased hydrogen peroxide (H2O2), malondialdehyde (MDA) and relative conductivity of membrane (RC) in a dose-dependent manner for different exposure times. However, the increased levels for H2O2, MDA and RC were not significant vis-a-vis the control when SO2 doses and exposure times were lower than 15 mg m(-3)/33 h, 30 mg m(-3)/24 h or 50 mg m(-3)/12 h (p>0.05). The results could be explained by the increases in the content of reduced form of glutathione (GSH), total glutathione (TGSH), ascorbate (AsA), ratio of GSH/GSSG (oxidized form of glutathione), activities of ascorbate peroxidase (APX), glutathione peroxidase (GPX), glutathione reductase (GR) and glutathione S-transferases (GST). On the other hand, exposure to higher doses of SO2 and longer exposure times, the values of the GSH-AsA dependent antioxidative indices decreased significantly (p<0.01), manifested by increased levels of H2O2. Furthermore, the levels of H2O2, MDA and RC varied little when SO2 doses and exposure times reached a 'critical' value (50 mg m(-3)/24 h). The defense ability of T. erecta to SO2 reached nearly extremity. To summarize, the response of T. erecta to elevated SO2 was related to higher H2O2 levels. GSH-AsA dependent detoxification pathway played an important role in against SO2-induced toxicity, although the defense response could not sufficiently alleviate oxidative damage when SO2 doses and exposure times reached critical value.
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Affiliation(s)
- Aili Wei
- Department of Biology, Taiyuan Normal University, Taiyuan, 030031, China.
| | - Baochun Fu
- Institute of Horticulture, Shanxi Academy of Agricultural Sciences, Taiyuan, 030031, China.
| | - Yunshan Wang
- Institute of Horticulture, Shanxi Academy of Agricultural Sciences, Taiyuan, 030031, China.
| | - Rui Li
- Department of Biology, Taiyuan Normal University, Taiyuan, 030031, China; School of Life Science, Shanxi University, Taiyuan 030006, China.
| | - Chao Zhang
- Institute of Horticulture, Shanxi Academy of Agricultural Sciences, Taiyuan, 030031, China.
| | - Dongmei Cao
- Institute of Horticulture, Shanxi Academy of Agricultural Sciences, Taiyuan, 030031, China.
| | - Xiaobing Zhang
- Department of Biology, Taiyuan Normal University, Taiyuan, 030031, China.
| | - Jiuju Duan
- Institute of Horticulture, Shanxi Academy of Agricultural Sciences, Taiyuan, 030031, China.
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