1,720,974 research outputs found
Calcium affects uranium responses in Arabidopsis thaliana: From distribution to toxicity
No full textUranium, a heavy metal and primordial radionuclide, is present in surface waters and soils both naturally and due to industrial activities. Uranium is known to be toxic to plants and its uptake and toxicity can be influenced by multiple factors such as pH and the presence of different ions. However, the precise role of the different ions in uranium uptake is not yet known. Here we investigated whether calcium influences uranium uptake and toxicity in the terrestrial plant Arabidopsis thaliana. To this end, A. thaliana plants were exposed to different calcium and uranium concentrations and furthermore, calcium channels were blocked using the calcium channel blocker lanthanum chloride (LaCl3). Fresh weight, relative growth rate, concentration of nutrients and uranium and gene expression of oxidative stress-related genes and calcium transporters were determined in roots and shoots. Calcium affected plant growth and oxidative stress in both control (no uranium) and uranium-exposed plants. In shoots, this was influenced by the total calcium concentration, but not by the different tested uranium concentrations. Uranium in turn did influence calcium uptake and distribution. Uranium-exposed plants grown in a medium with a higher calcium concentration showed an increase in gene expression of NADPH oxidases RBOHC and RBOHE and calcium transporter CAX7 after uranium exposure. In roots, these calcium-dependent responses in gene expression were not observed. This indicates that calcium indeed affects uranium toxicity, but only in shoots. In addition, a clear influence of uranium and LaCl3 (separately and combined) on the expression of calcium transporters was observed.PhD fellowship for A. M. was financially supported by the Belgian Nuclear Research Centre (SCK CEN). We would also like to thank our colleagues at BIS for the technical help in the setup and execution of the experiment
Lemna minor plants chronically exposed to ionising radiation: RNA-seq analysis indicates a dose rate dependent shift from acclimation to survival strategies
No full textEcotoxicological research provides knowledge on ionising radiation-induced responses in different plant species. However, the sparse data currently available are mainly extracted from acute exposure treatments. To provide a better understanding of environmental exposure scenarios, the response to stress in plants must be followed in more natural relevant chronic conditions. We previously showed morphological and biochemical responses in Lemna minor plants continuously exposed for 7 days in a dose-rate dependent manner. In this study responses on molecular (gene expression) and physiological (photosynthetic) level are evaluated in Leminor plants exposed to ionising radiation. To enable this, we examined the gene expression profiles of irradiated Leminor plants by using an RNA-seq approach. The gene expression data reveal indications that Leminor plants exposed at lower dose rates, can tolerate the exposure by triggering acclimation responses. In contrast, at the highest dose rate tested, a high number of genes related to antioxidative defense systems, DNA repair and cell cycle were differentially expressed suggesting that only high dose rates of ionising radiation drive Leminor plants into survival strategies. Notably, the photosynthetic process seems to be unaffected in Leminor plants among the tested dose rates. This study, supported by our earlier work, clearly indicates that plants shift from acclimation responses towards survival responses at increasing dose rates of ionising radiation. (C) 2017 Elsevier B.V. All rights reserved.The authors thank the Research foundation-Flanders (FWO) (G.A040.11N) and the European Commission Contract Fission 2010 -3.5.1-269672 Strategy for Allied Radioecology (www.starradioecology.org) for financial support of this work. Belgian nuclear research institute (SCKOCEN) is further thanked for funding the PhD of A. Van Hoeck
The nitric oxide suppressed Arabidopsis mutants-Atnoa1 and Atnia1nia2noa1-2 produce nitric oxide in MS growth medium and on uranium exposure
No full textThe mutants Atnoa1 and Atnia1nia2noa1-2 having a defective chloroplast developmental process, showed enhanced chlorophyll levels when they were grown on Murashige and Skoog (MS) medium and on exposure with uranium (U) on Hoagland medium. Thus we hypothesized that these mutants probably produced NO in MS medium and on exposure with U. Wild-type Col-0, Atnoa1, Atnia1nia2noa1-2 plants were cultured on modified Hoagland and 1/10 MS media and NO generation in the roots of these mutants was monitored using NO selective fluorescent dyes, DAF-2DA and F12E. Both Atnoa1 and Atnia1nia2noa1-2 triple mutants produced NO as observed by increases in DAF-2T and F12E fluorescence when these mutants were grown on MS medium but not on Hoagland medium. In presence of NO scavenger, methylene blue (MB, 200 mu M), DAF-2T and F12E fluorescence was completely abolished. On the other hand treatment of the plants with 25 mu M U triggered NO generation. Utreated Atnoa1 and Atnia1nia2noa1-2 plants upregulated genes (POR B, POR D, CHL D) involved in the chlorophyll biosynthesis. From these results it was concluded that Atnoa1 and Atnia1nia2noa1-2 are conditional NO producers and it appears that NO generation in plants substantially depends on growth medium and NIA1, NIA2 or NOA1 does not appear to be really involved in NO generation in MS medium or after U exposure.Authors are thankful to Dr. Jose Leon (Universidad Politecnica de Valencia) for his kind gift of Atnia1nia2noa1-2 mutant seeds. R.K. Tewari is grateful to Belgian Science Policy (BELSPO) fellowship and Department of Science and Technology, Government of India, for providing support to the Department of Botany, University of Lucknow under DST-PURSE program
Characterizing dose response relationships: Chronic gamma radiation in Lemna minor induces oxidative stress and altered polyploidy level
No full textThe biological effects and interactions of different radiation types in plants are still far from understood. Among different radiation types, external gamma radiation treatments have been mostly studied to assess the biological impact of radiation toxicity in organisms. Upon exposure of plants to gamma radiation, ionisation events can cause, either directly or indirectly, severe biological damage to DNA and other biomolecules. However, the biological responses and oxidative stress related mechanisms under chronic radiation conditions are poorly understood in plant systems. In the following study, it was questioned if the Lemna minor growth inhibition test is a suitable approach to also assess the radiotoxicity of this freshwater plant. Therefore, L. minor plants were continuously exposed for seven days to 12 different dose rate levels covering almost six orders of magnitude starting from 80 mu Gy h(-1) up to 1.5 Gy h(-1). Subsequently, growth, antioxidative defence system and genomic responses of L. minor plants were evaluated. Although L minor plants could survive the exposure treatment at environmental relevant exposure conditions, higher dose rate levels induced dose dependent growth inhibitions starting from approximately 27 mGy h(-1). A ten-percentage growth inhibition of frond area Effective Dose Rate (EDR10)) was estimated at 95 +/- 7 mGy h(-1), followed by 153 +/- 13 mGy h(-1) and 169 +/- 12 mGy h(-1) on fresh weight and frond number, respectively. Up to a dose rate of approximately 5 mGy h-1, antioxidative enzymes and metabolites remained unaffected in plants. A significant change in catalase enzyme activity was found at 27 mGy h(-1) which was accompanied with significant increases of other antioxidative enzyme activities and shifts in ascorbate and glutathione content at higher dose rate levels, indicating an increase in oxidative stress in plants. Recent plant research hypothesized that environmental genotoxic stress conditions can induce endoreduplication events. Here an increase in ploidy level was observed at the highest tested dose rate. In conclusion, the results revealed that in plants several mechanisms and pathways interplay to cope with radiation induced stress. (C) 2015 Elsevier Ltd. All rights reserved.The authors thank the Research foundation-Flanders (FWO) (G.A040.11N) and the European Commission (contract number: Fission-2010-3.5.1-269672) Strategy for Allied Radioecology (www.star-radioecology.org) for financial support of this work. Belgian nuclear research institute (SCK.CEN) is further thanked for funding the PhD of A. Van Hoeck
Uranium exposure induces nitric oxide and hydrogen peroxide generation in Arabidopsis thaliana
No full textUranium (U) is a nonessential and toxic heavy metal and radioactive element. Nitric oxide (NO) and hydrogen peroxide (H2O2) are intimately involved in the growth, development and metabolic function of plant cells. In addition to possible toxic activities, a role for these signalling molecules in the regulation of plant responses to toxic metals has been proposed. Here, we investigated the synthesis of NO and H2O2 in Arabidopsis thaliana seedlings exposed to 25 mu M U. We demonstrated that U induces NO and H2O2 production in the roots and leaves. Addition of the NO releasing compound, sodium nitroprusside (SNP) as well as the NO synthase inhibitor (L-NAME) to the plants, resulted in a decrease of the U-induced NO production and both alleviated U toxicity as indicated by plant growth (leaf area and biomass). Treatment with L-NAME further resulted in the disappearance of the U-induced H2O2 in the shoots of the plants. It appears that generation of NO and H2O2 is intimately linked in the toxicity response of U-exposed A. thaliana plants. (C) 2015 Elsevier B.V. All rights reserved.The authors wish to thank the Belgian Science Policy (BELSPO) for financially supporting the post-doctoral fellowship of R. Tewari
From crop left-overs to nutrient resource: growth-stimulating potential of biochar in nutrient solutions for wheat soilless cultivation systems
No full textTo reach the estimated food demands for 2050 in decreasingly suiting climates, current agricultural techniques have to be complemented by sustainably intensified practices. The current study repurposed wheat crop residues into biochar, and investigated its potential in different plant cultivation systems, including a hydroponic cultivation of wheat. Biochars resulting from varying pyrolysis parameters including feedstock composition (straw and chaff) and temperature (450°C and 600°C), were tested using a fast plant screening method. Biochar WBC450, produced from a combination of chaff and straw at 450°C, was selected for further plant experiments, and used in a static leaching experiment in the Arabidopsis thaliana cultivation medium. Increased pH and EC were observed, together with an increase of most macronutrient (K, Mg, P, S) and a decrease of most micronutrient (Fe, Mn, Zn) concentrations. Considering plant growth, application of biochar resulted in concentration-dependent effects in both tested plant species (A. thaliana and wheat). It improved the vegetative yield across all tested cultivation systems. Increases in K and S, and concentration-dependent decreases in Fe and Na content in wheatgrass were observed. Biochar influenced the reproduction of hydroponically cultivated wheat by increasing the number of spikes and the number of seeds per spike. The antioxidative capacity of wheat grass, and the seed sugar and starch contents remained unaffected by biochar application. This study contributes to innovation in soilless cultivation approaches of staple crops, within the framework of closing waste loops for a circular bioeconomy.The manuscript was published in Frontiers, Frontiers in Plant Science, Section Plant Nutrition, in a research topic called 'Application and Mechanism of Plant Biostimulants, Biochar, Fertilizer Products, and Other Nutrition-related Agrochemicals'. At the moment of copying this link, 18 articles were published in this Research Topic. I don't know how this translates to the metadata, but I mention it here in case it matters. No specific pages are available.
https://www.frontiersin.org/research-topics/62585/application-and-mechanism-of-plant-biostimulants-biochar-fertilizer-products-and-other-nutrition-related-agrochemicals/articles
The research was funded by VLAIO and Flanders' FOOD, which are no commercial facilities. The Funding information as written in the manuscript, in case it is needed anyway:
The author(s) declare financial support was received for the research, authorship and/or publication of this article. The authors declare that this study received funding from Flanders’ FOOD and Flanders Innovation and Entrepreneurship (VLAIO) as part of the SpaceBakery project (grant number HBC.2019.0100). The funder was not involved in the study design, collection, analysis, interpretation of data, the writing of this article or the decision to submit it for publication
The responses and recovery after gamma irradiation are highly dependent on leaf age at the time of exposure in rice (Oryza sativa L.)
No full textMost plant studies on the effects of ionizing radiation at the individual level mainly focus on the immediate responses and not on the responses elicited following recovery. Therefore, we investigated the effects of gamma radiation in rice seedlings exposed to four different gamma dose rates for 2 weeks, after which half of the plants were harvested immediately and the other half were allowed to recover for another 2 weeks. For plants that were harvested immediately, leaf 4 was sampled because it emerged during irradiation, whereas in recovery plants, leaf 4 was sampled as a follow-up as well as leaf 7, which emerged during the recovery period. Plant growth, the antioxidative potential, lignin content and the expression profiles of the rice gene Systemic Acquired Deficient 1 (OsSARD1) and of genes related to DNA repair/replication were analyzed. Overall, the responses elicited in leaf 4 of irradiated and recovery plants indicated that this leaf recovered from exposure via the establishment of a new homeostasis. Conversely, radiation-induced responses appeared in leaf 7 of recovery plants even though it was not directly exposed. Therefore, we hypothesize that a signaling mechanism comes into play to establish this radiation-induced signature, otherwise referred to as systemic acquired acclimation.This work was supported by a PhD grant for Jackline Kariuki from the Belgian Nuclear Research Centre (SCK . CEN)
β-Radiation Stress Responses on Growth and Antioxidative Defense System in Plants: A Study with Strontium-90 in Lemna minor
No full textIn the following study, dose dependent effects on growth and oxidative stress induced by β-radiation were examined to gain better insights in the mode of action of β-radiation induced stress in plant species. Radiostrontium (90Sr) was used to test for β-radiation induced responses in the freshwater macrophyte Lemna minor. The accumulation pattern of 90Sr was examined for L. minor root and fronds separately over a seven-day time period and was subsequently used in a dynamic dosimetric model to calculate β-radiation dose rates. Exposing L. minor plants for seven days to a 90Sr activity concentration of 25 up to 25,000 kBq·L−1 resulted in a dose rate between 0.084 ± 0.004 and 97 ± 8 mGy·h−1. After seven days of exposure, root fresh weight showed a dose dependent decrease starting from a dose rate of 9.4 ± 0.5 mGy·h−1. Based on these data, an EDR10 value of 1.5 ± 0.4 mGy·h−1 was estimated for root fresh weight and 52 ± 17 mGy·h−1 for frond fresh weight. Different antioxidative enzymes and metabolites were further examined to analyze if β-radiation induces oxidative stress in L. minor
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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