Recent advances in arsenic bioavailability, transport, and speciation in rice (original) (raw)
Related papers
Arsenic Uptake, Transport, Accumulation in Rice and Prospective Abatement Strategies -A Review
International Academic Publishing House, 2023
Recent reports claim that arsenic (As) toxicity affects millions of individuals worldwide. A significant problem for rice output and quality as well as for human health is the high content of arsenic (As), a non-essential poisonous metalloid, in rice grains. Therefore, substantial research has been done on the interactions between rice and As in recent years. As rice plants uptake at the root surface is impacted by factors like radical oxygen loss and iron plaque. The absorption and movement of various As species as well as the transfer to sub cellular compartments include a multitude of transporters, including phosphate transporters and aquaglyceroporins. As III and AsV are transported into the root by phosphate transporters and intrinsic channels that mimic nodulin 26. The silicic acid transporter may have a substantial impact on how methylated As, dimethylarsinic acid (DMA), and monomethylarsonic acid (MMA), enter the root. The issue of As contamination in rice is being addressed by researchers and practitioners to the best of their abilities. Making better plans may be aided by recent research on rice that explains the processes of arsenic ingestion, transportation, and metabolism at the rhizosphere. Common agronomic techniques, such as collecting rainwater for agricultural irrigation, using natural substances that aid in the methylation of arsenic, and biotechnology methods, may be investigated in an effort to lessen the uptake of arsenic by food crops. Innovative agronomic techniques and recent research findings on arsenic contamination in rice crops will be included in this review.
Arsenic uptake and accumulation mechanisms in rice species
Plants, 2020
Rice consumption is a source of arsenic (As) exposure, which poses serious health risks. In this study, the accumulation of As in rice was studied. Research shows that As accumulation in rice in Taiwan and Bangladesh is higher than that in other countries. In addition, the critical factors influencing the uptake of As into rice crops are defined. Furthermore, determining the feasibility of using effective ways to reduce the accumulation of As in rice was studied. AsV and AsIII are transported to the root through phosphate transporters and nodulin 26-like intrinsic channels. The silicic acid transporter may have a vital role in the entry of methylated As, dimethylarsinic acid (DMA) and monomethylarsonic acid (MMA), into the root. Amongst As species, DMA(V) is particularly mobile in plants and can easily transfer from root to shoot. The OsPTR7 gene has a key role in moving DMA in the xylem or phloem. Soil properties can affect the uptake of As by plants. An increase in organic matter and in the concentrations of sulphur, iron, and manganese reduces the uptake of As by plants. Amongst the agronomic strategies in diminishing the uptake and accumulation of As in rice, using microalgae and bacteria is the most efficient.
The Journey of Arsenic from Soil to Grain in Rice
Frontiers in Plant Science
Arsenic (As) is a non-essential toxic metalloid whose elevated concentration in rice grains is a serious issue both for rice yield and quality, and for human health. The rice-As interactions, hence, have been studied extensively in past few decades. A deep understanding of factors influencing As uptake and transport from soil to grains can be helpful to tackle this issue so as to minimize grain As levels. As uptake at the root surface by rice plants depends on factors like iron plaque and radial oxygen loss. There is involvement of a number of transporters viz., phosphate transporters and aquaglyceroporins in the uptake and transport of different As species and in the movement to subcellular compartments. These processes are also affected by sulfur availability and consequently on the level of thiol (-SH)-containing As binding peptides viz., glutathione (GSH) and phytochelatins (PCs). Further, the role of phloem in As movement to the grains is also suggested. This review presents a detailed map of journey of As from soil to the grains. The implications for the utilization of available knowledge in minimizing As in rice grains are presented.
Arsenic Transport in Rice and Biological Solutions to Reduce Arsenic Risk from Rice
Frontiers in plant science, 2017
Rice (Oryza sativa L.) feeds ∼3 billion people. Due to the wide occurrence of arsenic (As) pollution in paddy soils and its efficient plant uptake, As in rice grains presents health risks. Genetic manipulation may offer an effective approach to reduce As accumulation in rice grains. The genetics of As uptake and metabolism have been elucidated and target genes have been identified for genetic engineering to reduce As accumulation in grains. Key processes controlling As in grains include As uptake, arsenite (AsIII) efflux, arsenate (AsV) reduction and AsIII sequestration, and As methylation and volatilization. Recent advances, including characterization of AsV uptake transporter OsPT8, AsV reductase OsHAC1;1 and OsHAC1;2, rice glutaredoxins, and rice ABC transporter OsABCC1, make many possibilities to develop low-arsenic rice.
Arsenic accumulation in rice (Oryza sativa L.) is influenced by environment and genetic factors
• Biogeochemical factors govern As speciation in paddy soil-water systems. • PO 3À 4 and Si transporters involve As(III), As(V), MMA(V), and DMA(V) uptake. • As(III) efflux and complexation with thiols limit As(III) translocation. • DMA(V) possesses the highest translo-cation efficiency (grain-to-root). Editor: Xinbin Feng Arsenic (As) elevation in paddy soils will have a negative impact on both the yield and grain quality of rice (Oryza sativa L.). The mechanistic understanding of As uptake, translocation, and grain filling is an important aspect to produce rice grains with low As concentrations through agronomical, physico-chemical, and breeding approaches. A range of factors (i.e. physico-chemical, biological, and environmental) govern the speciation and mobility of As in paddy soil-water systems. Major As uptake transporters in rice roots, such as phosphate and aquaglyceroporins, assimilate both inorganic (As(III) and As(V)) and organic As (DMA(V) and MMA(V)) species from the rice rhizosphere. A number of metabolic pathways (i.e. As (V) reduction, As(III) efflux, and As(III)-thiol complexation and subsequent sequestration) are likely to play a key role in determining the translocation and substantial accumulation of As species in rice tissues. The order of translocation efficiency (caryopsis-to-root) for different As species in rice plants is comprehensively evaluated as follows: DMA(V) N MMA(V) N inorganic As species. The loading patterns of both inorganic and organic As species into the rice grains are largely dependent on the genetic makeup and maturity stage of the rice plants together with environmental interactions. The knowledge of As metabolism in rice plants and how it is affected by plant genetics and environmental factors would pave the way to develop adaptive strategies to minimize the accumulation of As in rice grains.
Scientific Reports
Environmental contamination of arsenic (As) and its accumulation in rice (Oryza sativa L.) is of serious human health concern. In planta speciation of As is an important tool to understand As metabolism in plants. In the present study, we investigated root to shoot As translocation and speciation in rice exposed to inorganic and methylated As. Arsenate (As V) and methylarsonate (MA V) were efficiently reduced to arsenite (As III) and MA III , respectively in rice root and shoot but no trivalent form of dimethylarsinate (DMA V) was detected. Further, up to 48 and 83% of root As in As V and MA V exposed plants, respectively were complexed with various thiols showing up to 20 and 16 As species, respectively. Several mixed As-and MA-complexes with hydroxymethyl-phytochelatin, DesGlyphytochelatin, hydroxymethyl-GSH and cysteine were identified in rice. Despite high complexation in roots, more As was translocated to shoots in MA V exposed plants than As V , with shoot/root As transfer factor being in order DMA V > MA V > As V. Moreover, in shoots 78% MA III and 71% As III were present as weakly bound species which is alarming, as MA III has been found to be more cytotoxic than As III for human and it could also be an important factor inducing straighthead (spikelet sterility disorder) in rice. Arsenic (As) is ubiquitously present, considered as a non-essential metalloid for plants and animals, and poses serious health hazards to humans. High levels of As in soil and water have been reported around the world through geothermal, mining and industrial activities, agricultural applications and contaminated ground water 1,2. Ground water of many countries, particularly in the Indian subcontinent, are naturally highly enriched with As and posing toxicity through drinking water and food chain contamination 3,4. Agricultural fields are the net sink for thousands of tons of As being transferred each year through contaminated irrigation water in these areas 5,6. The typical As concentration in soil solution of paddy fields varies from 0.01 to 3 μ M, however, as high as 33 μ M As has been reported in a paddy field irrigated with As-laden ground water 7,8. Further, a significant yield loss has been reported in the crops grown in As contaminated areas 8. Thus, a threat to the sustainability of food production has been recognized as the other side of the As calamity 8,9. Understanding the mechanism of As toxicity in plants is crucial to find a sustainable solution to the problem. Arsenic exists in various chemical forms in the environment, which differ considerably in plant uptake, mobility and toxicity. Thus, speciation of As in various plant parts is an important tool to understand the in planta transformation and metabolism of various As species. Inorganic arsenate [HAsO 4 2− or As V ] and arsenite [H 2 AsO 3 − or As III ] are the predominant species in water and soil, however, in soil considerable amount of methylated arsenic species [methylarsonic acid; MA V and dimethylarsinic acid; DMA V ] may also be present due to microbial action 10-13 or due to past uses of methylated As compounds (sodium salt of MA V and DMA V or cacodylic acid) as pesticides and herbicides 4,14. Arsenate is taken up by the plants through phosphate transporters 15 , while As III is taken up by nodulin26-like intrinsic (NIPs) aquaporin channels, along with neutral solutes like glycerol, ammonia and silicic acid 16. The rice aquaporin Lsi1 also
Chemosphere, 2017
Arsenic (As) exposure from rice consumption has now become a global health issue. This study aimed to investigate the effects of rice rhizosphere oxic conditions on silicate transporter (responsible for arsenite transportation) expressions, and on As accumulation and speciation in four rice genotypes, including two hybrid genotypes (Xiangfengyou9, Shenyou9586) and two indica subspecies (Xiangwanxian17, Xiangwanxian12). Oxic and anoxic treatments have different effects on root length (p < 0.001) and weight (p < 0.05). Total As concentrations in roots were dramatically lower in oxic treatments (88.8-218 mg/kg), compared to anoxic treatments (147-243 mg/kg) (p < 0.001). Moreover, root and shoot arsenite concentrations in oxic treatments were lower than that in anoxic treatments in arsenite treatments. The relative abundance of silicate transporter expressions displayed a trend of down-regulation in oxic treatments compared to anoxic treatments, especially significantly differe...
Metallomics, 2019
Arsenic (As), classified as a “metalloid” element, is well known for its carcinogenicity and other toxic effects to humans. Arsenic exposure in plants results in the alteration of the physiochemical and biological properties and consequently, loss of crop yield. Being a staple food for half of the world's population, the consumption of As-contaminated rice grain by humans may pose serious health issues and risks for food security. In this study, we have described the principal understanding of the molecular basis of arsenic toxicity and accumulation in plant parts. We described the measures for decreasing As accumulation in rice and understanding the mechanism and transport of As uptake, its transport from root to shoot to rice grain, its metabolism, detoxification, as well as the mechanisms lying behind its accumulation in rice grains. There are various checkpoints, such as the tuning of AsV/Pi specific Pi transporters, arsenate reductase, transporters that are involved in the ...
Rice is the main staple carbohydrate source for billions of people worldwide. Natural geogenic and anthropogenic sources has led to high arsenic (As) concentrations in rice grains. This is because As is highly bioavailable to rice roots under conditions in which rice is cultivated. A multifaceted and inter-disciplinary understanding, both of short-term and long-term effects, are required to identify spatial and temporal changes in As contamination levels in paddy soil-water systems. During flooding, soil pore waters are elevated in inorganic As compared to dryland cultivation systems, as anaerobism results in poorly mobile As(V), being reduced to highly mobile As(III). The formation of iron (Fe) plaque on roots, availability of metal (hydro)oxides (Fe and Mn), organic matter, clay mineralogy and competing ions and compounds (PO 4 3À and Si(OH) 4) are all known to influence As(V) and As(III) mobility in paddy soil-water environments. Microorganisms play a key role in As transformation through oxidation/reduction, and methylation/volatilization reactions, but transformation kinetics are poorly understood. Scientific-based optimization of all biogeochemical parameters may help to significantly reduce the bioavailability of inorganic As.