Regulation of growth and metabolism in rice (Oryza sativa L.) by arsenic and its possible reversal by phosphate
TL;DR: The effect of arsenate with or without phosphate on the growth and metabolism in rice seedlings cv. MTU1010 was studied in this article, where arsenic was more toxic for root growth, than for shoot growth.
Abstract: The effect of arsenate with or without phosphate on the growth and metabolism in rice seedlings cv. MTU1010 was studied. In the test, cv. arsenic was more toxic for root growth, than for shoot growth, where root hairs were fewer and short, roots were characteristically stubby, brittle and root tips gradually turned brown. Arsenic caused damage to the root epidermal cells and aerenchymatous cortex. The level of total chlorophyll, chlorophyll-a, chlorophyll-b and fluorescence intensity were decreased in arsenic treated rice seedlings. Arsenic toxicity affected the activities of different antioxidant scavenging enzymes in the test seedlings. Activities of superoxide dismutase and ascorbic acid oxidase were increased, whereas catalase and catechol peroxidase activities were decreased by arsenic application. In these seedlings, the oxidative stress has been observed with arsenic treatments and the level of proline, H2O2 and malondialdehyde contents were increased. Joint application of phosphate with a...
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TL;DR: This review highlights the importance of the As-induced generation of reactive oxygen species (ROS) as well as their damaging impacts on plants at biochemical, genetic, and molecular levels.
Abstract: Environmental contamination with arsenic (As) is a global environmental, agricultural and health issue due to the highly toxic and carcinogenic nature of As. Exposure of plants to As, even at very low concentration, can cause many morphological, physiological, and biochemical changes. The recent research on As in the soil-plant system indicates that As toxicity to plants varies with its speciation in plants (e.g., arsenite, As(III); arsenate, As(V)), with the type of plant species, and with other soil factors controlling As accumulation in plants. Various plant species have different mechanisms of As(III) or As(V) uptake, toxicity, and detoxification. This review briefly describes the sources and global extent of As contamination and As speciation in soil. We discuss different mechanisms responsible for As(III) and As(V) uptake, toxicity, and detoxification in plants, at physiological, biochemical, and molecular levels. This review highlights the importance of the As-induced generation of reactive oxygen species (ROS), as well as their damaging impacts on plants at biochemical, genetic, and molecular levels. The role of different enzymatic (superoxide dismutase, catalase, glutathione reductase, and ascorbate peroxidase) and non-enzymatic (salicylic acid, proline, phytochelatins, glutathione, nitric oxide, and phosphorous) substances under As(III/V) stress have been delineated via conceptual models showing As translocation and toxicity pathways in plant species. Significantly, this review addresses the current, albeit partially understood, emerging aspects on (i) As-induced physiological, biochemical, and genotoxic mechanisms and responses in plants and (ii) the roles of different molecules in modulation of As-induced toxicities in plants. We also provide insight on some important research gaps that need to be filled to advance our scientific understanding in this area of research on As in soil-plant systems.
513 citations
Cites background from "Regulation of growth and metabolism..."
...[212] found that the toxicity of As was reduced when plants of Oryza sativa were supplied with a Pi source....
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...Similarly, a decline in protease was documented in As-stressed Triticum aestivum [238], Pteris vittata and Pteris ensiformis [196], Oryza sativa [212], and Phaseolus aureus [214] seeds....
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...When the seedlings of Triticum aestivum and Oryza sativa were treated with various levels of As(III) and As(V), proline was accumulated in these plants depending on the level of As in growth medium [212,301]....
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...[209,211], Oryza sativa [212], Spinacia oleracea [213], Pisum sativum [17], and Vicia faba [18] and seeds of Anadenanthera peregrina and Myracrodruon urundeuva [128]....
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TL;DR: This review focuses on the effects of heavy metal wastes generated from gold mining activities on the environment and the various mechanisms used by bacteria to counteract the effect of these heavy metals in their immediate environment.
Abstract: Mining activities can lead to the generation of large quantities of heavy metal laden wastes which are released in an uncontrolled manner, causing widespread contamination of the ecosystem Though some heavy metals classified as essential are important for normal life physiological processes, higher concentrations above stipulated levels have deleterious effects on human health and biota Bacteria able to withstand high concentrations of these heavy metals are found in the environment as a result of various inherent biochemical, physiological, and/or genetic mechanisms These mechanisms can serve as potential tools for bioremediation of heavy metal polluted sites This review focuses on the effects of heavy metal wastes generated from gold mining activities on the environment and the various mechanisms used by bacteria to counteract the effect of these heavy metals in their immediate environment
435 citations
Cites background from "Regulation of growth and metabolism..."
...Arsenic is one of the most dangerous heavy metals of worldwide environmental concern [80] due to its potential toxicity....
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TL;DR: This review makes a case for taking steps to prevent or limit crop uptake of arsenic, wherever possible, and to work toward a long-term solution to the presence of arsenic in agronomic systems.
163 citations
Cites background from "Regulation of growth and metabolism..."
...Plants vary in their tolerance to arsenic, and the stress response differs for each arsenic species (Choudhury et al., 2011; Shri et al., 2009; Chakrabarty et al., 2009)....
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30 Jun 2020
TL;DR: The significance of ZnO–NPs in alleviating the toxicity of As in soybean plants is confirmed, as well as the enzymes involved in the ascorbate–glutathione cycle including superoxide dismutase (SOD), catalase (CAT), asCorbate peroxidase (APX) and glutathione reductase (GR) showed a significant increase in their activity with the application of ZNO-NPs.
Abstract: Accumulation of arsenic (As) in soils is increasing consistently day-by-day, which has resulted in increased toxicity of this element in various crop plants. Arsenic interferes with several plant metabolic processes at molecular, biochemical and physiological levels, which result in reduced plant productivity. Hence, the introduction of novel ameliorating agents to combat this situation is the need of the hour. The present study was designed to examine the effect of zinc oxide nanoparticles (ZnO-NPs) in As-stressed soybean plants. Various plant growth factors and enzymes were studied at varying concentrations of As and ZnO-NPs. Our results showed that with the application of ZnO-NPs, As concentration declined in both root and shoot of soybean plants. The lengths of shoot and root, net photosynthetic rate, transpiration, stomatal conductance, photochemical yield and other factors declined with an increase in external As level. However, the application of ZnO-NPs to the As-stressed soybean plants resulted in a considerable increase in these factors. Moreover, the enzymes involved in the ascorbate-glutathione cycle including superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR) showed a significant increase in their activity with the application of ZnO-NPs to the As-stressed plants. Hence, our study confirms the significance of ZnO-NPs in alleviating the toxicity of As in soybean plants.
138 citations
Cites background from "Regulation of growth and metabolism..."
...[38] in Oryza sativa and Siddiqui, et al....
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TL;DR: This review has attempted to collate recent advances on mechanism(s) of As uptake by plants, toxicity responses [physiological, biochemical and molecular] exerted by As, and roles of varied molecules in amelioration of As effects in crop plants.
Abstract: Arsenic (As) is one of the highly toxic metalloids distributed ubiquitously in nature. Two inorganic forms of As are present abundantly: arsenite (AsIII) and arsenate (AsV), former being 100 times more toxic than latter. Arsenic is a well known inducer of reactive oxygen species (ROS) in crop plants either directly during conversion of AsV to AsIII or indirectly via inactivation of the antioxidants by binding to their thiol groups. Arsenic-mediated oxidative stress causes an array of metabolic dysfunctions in plants. Therefore, in recent years, demonstration of various mechanisms to improve crop productivity and/or alleviation of As toxicity has become a prime concern. Modulation of cellular thiol molecules for protection against ROS-induced damage has been used as a strategy against As. Accrual of proline, polyphenols and exogenous application of salicylic acid, nitric oxide, phosphate and potassium show protection against As-mediated injuries in crop plants. Proline, nitric oxide and salicylic acid display defensive functions by activating antioxidant machinery of crop plants whereas phosphate and potassium reduce As toxicity by controlling As-uptake or maintaining cellular protein and antioxidant enzymes in plants. Likewise, polyphenols serve as antioxidants and reduce activities of ROS synthesizing enzymes, thereby confering As-stress tolerance. In this review we have attempted to collate recent advances on 1) mechanism(s) of As uptake by plants, 2) toxicity responses [physiological, biochemical and molecular] exerted by As, and 3) roles of varied molecules in amelioration of As effects in crop plants. Gaps in the existing knowledge and future research prospects have also been highlighted in this review.
124 citations
Cites background from "Regulation of growth and metabolism..."
...This could be the reason why Aspretreated seedlings of Oryza sativa L. when supplemented with dipotassium hydrogen phosphate (a source of phosphate), showed reduced toxicity to As (Choudhury et al. 2011)....
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...However, under As-exposure, distorted activities of proteases resulted in altered amounts of proteins and free amino acids that in turn inhibited the growth and development of Oryza sativa L. and Vigna radiata L. (Choudhury et al. 2011; Ismail 2012)....
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...Recently, exogenous applications of nitric oxide (NO), salicylic acid (SA), phosphate and potassium have been shown to mitigate As-stress responses in plants (Senaratna et al. 2000; Choudhury et al. 2011; Ismail 2012; Umar et al. 2013)....
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...Singh et al. (2007) and Choudhury et al. (2011) observed accumulation of MDA in As treated Phaseolus aureus Roxb. and Oryza sativa L. seedlings, and concluded that it was the resultant of oxidative injury caused by imbalance in maintaining the homeostatic control over the photosynthetic light…...
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...when supplemented with dipotassium hydrogen phosphate (a source of phosphate), showed reduced toxicity to As (Choudhury et al. 2011)....
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References
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TL;DR: Evidence that a copper enzyme, polyphenoloxidase (otherwise known as tyrosinase or catecholase), is localized in the chloroplasts of spinach beet (chard), Beta vu?garis is presented.
Abstract: The chloroplast, as the seat of chlorophyll pigments in plants, occupies a unique position in the economy of the green cell. In recent years there has been a renewed interest in the reactions and properties of chloroplasts as a result of the work of Hill (11, 12) and Hill and Scarisbrick (13, 14) who demonstrated that the reaction characteristic of photosynthesis in green plants, the evolution of oxygen, occurs in appreciable quantities in isolated chloroplasts under the influence of light and in the presence of suitable oxidants (2, 7, 8, 26). In the course of an investigation of oxygen evolution by isolated chloroplasts it was deemed important to explore their enzymatic composition. Of special interest were considered enzymes capable of participating in oxidation-reduction reactions, and more particularly, those localized principally, if not entirely, in the chloroplasts. This paper presents evidence that a copper enzyme, polyphenoloxidase (otherwise known as tyrosinase or catecholase), is localized in the chloroplasts of spinach beet (chard), Beta vu?garis.
20,139 citations
"Regulation of growth and metabolism..." refers methods in this paper
...Total chlorophyll, chlorophyll-a and chlorophyll-b contents were measured from the rice leaves according to Arnon (1949)....
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TL;DR: In this article, a simple colorimetric determination of proline in the 0.1 to 36.0 μmoles/g range of fresh weight leaf material was presented.
Abstract: Proline, which increases proportionately faster than other amino acids in plants under water stress, has been suggested as an evaluating parameter for irrigation scheduling and for selecting drought-resistant varieties. The necessity to analyze numerous samples from multiple replications of field grown materials prompted the development of a simple, rapid colorimetric determination of proline. The method detected proline in the 0.1 to 36.0 μmoles/g range of fresh weight leaf material.
15,328 citations
"Regulation of growth and metabolism..." refers methods in this paper
...1 g tissue of rice seedlings was extracted with 5 ml of 0.1 M sulphosalicylic acid and centrifuged at 5000 g for 30 min (Bates et al. 1973)....
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TL;DR: Key steps of the signal transduction pathway that senses ROIs in plants have been identified and raise several intriguing questions about the relationships between ROI signaling, ROI stress and the production and scavenging ofROIs in the different cellular compartments.
9,395 citations
"Regulation of growth and metabolism..." refers background in this paper
...Although arsenic is not a redox metal, the production of ROS in plants on exposure to inorganic arsenic is associated with arsenic valence change (Mittler 2002)....
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...Similarly, malondialdehyde (MDA) which is often used as an indicator of oxidative damage is produced during peroxidation of membrane lipid by decomposition of polyunsaturated fatty acid (Mittler 2002)....
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...Although arsenic is not a redox metal, the production of ROS in plants on exposure to inorganic arsenic is associated with arsenic valence change (Mittler 2002 )....
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TL;DR: Nine of the enzyme activities were eliminated with cyanide treatment suggesting that they may be cupro-zinc enzymes, whereas one was cyanide-resistant and may be a manganese enzyme.
Abstract: Shoots, roots, and seeds of corn (Zea mays L., cv. Michigan 500), oats (Avena sativa L., cv. Au Sable), and peas (Pisum sativum L., cv. Wando) were analyzed for their superoxide dismutase content using a photochemical assay system consisting of methionine, riboflavin, and p-nitro blue tetrazolium. The enzyme is present in the shoots, roots, and seeds of the three species. On a dry weight basis, shoots contain more enzyme than roots. In seeds, the enzyme is present in both the embryo and the storage tissue. Electrophoresis indicated a total of 10 distinct forms of the enzyme. Corn contained seven of these forms and oats three. Peas contained one of the corn and two of the oat enzymes. Nine of the enzyme activities were eliminated with cyanide treatment suggesting that they may be cupro-zinc enzymes, whereas one was cyanide-resistant and may be a manganese enzyme. Some of the leaf superoxide dismutases were found primarily in mitochondria or chloroplasts. Peroxidases at high concentrations interfere with the assay. In test tube assays of crude extracts from seedlings, the interference was negligible. On gels, however, peroxidases may account for two of the 10 superoxide dismutase forms.
4,882 citations
"Regulation of growth and metabolism..." refers methods in this paper
...Superoxide dismutase (SOD; EC 1.15.1.1) activity was assayed by using the nitroblue tetrazolium method (Giannopolitis and Ries 1977)....
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TL;DR: Calculated loading rates of trace metals into the three environmental compartments demonstrate that human activities now have major impacts on the global and regional cycles of most of the trace elements.
Abstract: Calculated loading rates of trace metals into the three environmental compartments demonstrate that human activities now have major impacts on the global and regional cycles of most of the trace elements. There is significant contamination of freshwater resources and an accelerating accumulation of toxic metals in the human food chain.
4,097 citations