Strategies for Reducing Arsenic Content in Rice: A review (original) (raw)
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Environmental Science and Pollution Research, 2017
Arsenic (As) is a toxic metalloid. Serious concerns have been raised in literature owing to its potential toxicity towards living beings. The metalloid causes various waterand food-borne diseases. Among food crops, rice contains the highest concentrations of As. Consuming Ascontaminated rice results in serious health issues. Arsenic concentration in rice is governed by various factors in the rhizosphere such as availability and concentration of various mineral nutrients (iron, phosphate, sulfur and silicon) in soil solution, soil oxidation/reduction status, inter-conversion between organic and inorganic As compounds. Agronomic and civil engineering methods can be adopted to decrease As accumulation in rice. Agronomic methods such as improving soil porosity/aeration by irrigation management or creating the conditions favorable for As-precipitate formation, and decreasing As uptake and translocation by adding a inorganic nutrients that compete with As are easy and cost effective techniques at field scale. This review focuses on the factors regulating and competing As in soil-plant system and As accumulation in rice grains. Therefore, it is suggested that judicious use of water, management of soil, antagonistic effects of various inorganic plant-nutrients to As should be considered in rice cultivated areas to mitigate the building up of As in human food chain and with minimum negative impact to the environment.
Chemosphere, 2017
Growing rice on arsenic (As)-contaminated soil or irrigating with As-contaminated water leads to significant accumulation of As in grains. Moreover, rice accumulates more As into grains than other cereal crops. Thus, rice consumption has been identified as a major route of human exposure to As in many countries. Inorganic As species are carcinogenic and could pose a considerable health risk to humans even at low dietary concentration. Genotypic variation and concentration of nutrients such as iron, manganese, phosphate, sulfur and silicon are the two main factors that affect As accumulation in rice grains. Therefore, in addition to better growth and yield of plants, application of specific nutrients in optimum quantities offers an added benefit of decreasing As content in rice grains. These nutrient elements influence speciation of As in rhizosphere, compete with As for root uptake and interfere with As translocations to the shoot and ultimately accumulation in grains. This papers c...
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 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 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.
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.
Arsenic (As), a class one carcinogen, reflects a disastrous environmental threat due to its presence in each and every compartment of the environment. The high toxicity of As is notably present in its inorganic forms. Irrigation with As contaminated groundwater in rice fields increases As concentration in topsoil and its bioavailability for rice crops. However, most of the As in paddy field topsoils is present as As(III) form, which is predominant in rice grain. According to the OECD-FAO, rice is the second most extensively cultivated cereal throughout the world. This cereal is a staple food for a large number of populations in most of the developing countries in sub-Saharan Africa, Latin America, South and South-east Asia. Rice consumption is one of the major causes of chronic As diseases including cancer for Asian populations. Thus, this review provides an overview concerning the conditions involved in soil that leads to As entrance into rice crops, phytotoxicity and metabolism of As in rice plants. Moreover, the investigations of the As uptake in raw rice grain are compiled, and the As biotransfer into the human diet is focused. The As uptake by rice crop represents an important pathway of As exposure in countries with high rice and rice-based food consumption because of its high (more than the hygienic level) As levels found in edible plant part for livestock and humans.
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.
Recent advances in arsenic bioavailability, transport, and speciation in rice
Environmental science and pollution research international, 2015
Widespread arsenic (As) contamination in paddy rice (Oryza sativa) from both geologic and anthropogenic origins is an increasing concern globally. Substantial efforts have been made to elucidate As transformation and uptake processes in rhizosphere and metabolism in rice plant, which provides an essential foundation for the development of mitigation strategies. However, a range of crucial mechanisms from As mobilization in rhizosphere to transport to grains remain poorly understood. To provide new insight into the underlying mechanisms of As accumulation in rice, a range of new perspectives on As bioavailability, transport pathways, and in situ speciation are reviewed here. Specifically, the prominent effects of water regime, Fe plaque, and biochar on As mobilization in rice rhizosphere are discussed critically. An updated understanding of arsenite (AsIII) and methylated As transport from root to vascular bundle and grain is integrated and discussed in detail. Special attention is g...