Rhizospheric iron and arsenic bacteria affected by water regime: Implications for metalloid uptake by rice

Zecchin, Sarah; Corsini, A.; Martín, María; Romani, Marco; Beone, Gian Maria; Zanchi, R.; Zanzo, Elena; Tenni, Daniele; Fontanella, Maria Chiara; Cavalca, L.

doi:10.1016/j.soilbio.2016.12.021

Cited by 45 publications

(26 citation statements)

References 52 publications

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“…Three samples exceed the Chinese maximum total As concentration for rice (that excludes brown rice), which is set at 500 mg As kg À1 (USDA 2014). The large range in As concentration across Australian rice samples almost certainly eventuates from cultivar differences (Kuramata et al 2013;Lemos Batista et al 2014) and numerous site-specific factors such as variability in soil As concentration, root porosity and root density, oxygenation capacity of roots, iron plaque formation, N, P and Si uptake and competition, and transpiration rates, all of which can influence As uptake by rice (Liu et al 2005;Liu et al 2006;Seyfferth et al 2016;Zecchin et al 2017b;Zia et al 2017). Agronomic practices such as flooding, which creates anaerobic conditions and influences As speciation (discussed below) are also responsible for differences in rice As concentrations.…”

Section: Resultsmentioning

confidence: 99%

“…Other As species such as dimethylarsinic acid (DMA), monomethylarsonate (MA) and tetramethylarsonium ions (TETRA) have also been reported in rice (Batista et al 2011;Hansen et al 2011;Hua et al 2011), and are probably the result of the reduction and methylation of inorganic As in rhizosphere soils under anaerobic growth conditions (Lomax et al 2012 ;Zhao et al 2013;Zecchin et al 2017b) as genes responsible for As methylation have yet to be found in rice (Ye et al 2012). DMA is thought to be the cause of straighthead in rice (Limmer et al 2018).…”

Section: Introductionmentioning

confidence: 99%

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Arsenic concentrations and speciation in Australian and imported rice and commercial rice products

et al. 2018

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Environmental contextIn countries where inhabitants are not exposed to arsenic-contaminated drinking water, food is the major source of potentially toxic inorganic arsenic. To complement the existing worldwide dataset on arsenic in rice, data are presented on Australian- and overseas-grown rice, and assessed in terms of possible risk. Only a diet comprising multiple serves of some rice products per day poses a potential risk to young children. AbstractArsenic concentrations and speciation measurements were determined for six varieties of Australian-grown rice (n = 130), imported rice (n = 53) and rice products (n = 56) from supermarkets. Total As, inorganic As and dimethylarsinic acid (DMA) concentrations in Australian rice ranged from 16 to 630 µg As kg−1 (mean ± s.d.: 220 ± 122 µg kg−1), 16 to 250 µg As kg−1 (92 ± 52 µg As kg−1) and <5 to 432 µg As kg−1 (125 ± 109 µg As kg−1), respectively. Total As, inorganic As and DMA concentrations in imported rice ranged between 31 and 376 µg As kg−1 (130 ± 98 µg kg−1), 17 and 198 µg As kg−1 (73 ± 40 µg As kg−1) and <5 and 327 µg As kg−1 (84 ± 92 µg As kg−1) respectively. Few samples exceeded the guidelines for inorganic As in polished rice. In rice products, total As, inorganic As and DMA concentrations ranged between 21 and 480 µg As kg−1 (160 ± 110 µg As kg−1), 20 and 255 µg As kg−1 (92 ± 78 µg As kg−1) and <5 and 340 µg As kg−1 (65 ± 69 µg As kg−1) respectively. Sixteen samples exceeded the 100 µg kg−1 maximum for inorganic As concentration in rice foods for infants and young children. Ingestion of multiple serves of some rice products poses a potential risk. Environmental chemistry gaps, on processes influencing As occurrence in rice, are discussed.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Arsenic concentrations and speciation in Australian and imported rice and commercial rice products

et al. 2018

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“…Thus, microbial processes that oxidize As making it less bioavailable could not occur, allowing As to be present in the soil solution as the reduced arsenite form, which is easily taken up by rice ( Ma et al, 2008 ; Norton et al, 2010 ; Zhao et al, 2010 ). In comparison, in both the field 2014 and the greenhouse study, the imposed AWD cycles were severe enough to make the soil fully aerobic, allowing for geochemical and microbial processes to oxidize As, resulting in sequestration into iron and manganese oxides ( Takahashi et al, 2004 ; Zecchin et al, 2017 ; Maguffin et al, 2020 ).…”

Section: Discussionmentioning

confidence: 99%

“…Allele at identified QTLs affecting grain inorganic arsenic content processes to oxidize As, resulting in sequestration into iron and manganese oxides (Takahashi et al, 2004;Zecchin et al, 2017;Maguffin et al, 2020). The AWD implemented in the greenhouse pots was more severe (20% VWC) and controlled than that realized in the field (30-40% VWC).…”

Section: Grain Ias Phenotypementioning

confidence: 99%

Grain Inorganic Arsenic Content in Rice Managed Through Targeted Introgressions and Irrigation Management

et al. 2021

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Arsenic (As) accumulation in rice grain is a significant public health concern. Inorganic As (iAs) is of particular concern because it has increased toxicity as compared to organic As. Irrigation management practices, such as alternate wetting and drying (AWD), as well as genotypic differences between cultivars, have been shown to influence As accumulation in rice grain. A 2 year field study using a Lemont × TeQing backcross introgression line (TIL) mapping population examined the impact of genotype and AWD severity on iAs grain concentrations. The “Safe”-AWD [35–40% soil volumetric water content (VWC)] treatment did not reduce grain iAs levels, whereas the more severe AWD30 (25–30% VWC) consistently reduced iAs concentrations across all genotypes. The TILs displayed a range of iAs concentrations by genotype, from less than 10 to up to 46 μg kg–1 under AWD30 and from 28 to 104 μg kg–1 under Safe-AWD. TIL grain iAs concentrations for flood treatments across both years ranged from 26 to 127 μg kg–1. Additionally, seven quantitative trait loci (QTLs) were identified in the mapping population associated with grain iAs. A subset of eight TILs and their parents were grown to confirm field-identified grain iAs QTLs in a controlled greenhouse environment. Greenhouse results confirmed the genotypic grain iAs patterns observed in the field; however, iAs concentrations were higher under greenhouse conditions as compared to the field. In the greenhouse, the number of days under AWD was negatively correlated with grain iAs concentrations. Thus, longer drying periods to meet the same soil VWC resulted in lower grain iAs levels. Both the number and combinations of iAs-affecting QTLs significantly impacted grain iAs concentrations. Therefore, identifying more grain iAs-affecting QTLs could be important to inform future breeding efforts for low iAs rice varieties. Our study suggests that coupling AWD practices targeting a soil VWC of less than or equal to 30% coupled with the use of cultivars developed to possess multiple QTLs that negatively regulate grain iAs concentrations will be helpful in mitigating exposure of iAs from rice consumption.

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“…Soil microorganisms influence on As biogeochemistry affecting the soil redox conditions and the release of As from As-bearing minerals into pore water [ 14 , 15 ]. Traditional flooded cultivation practice mostly triggers enhanced bioavailability of As in rice.…”

Section: Introductionmentioning

confidence: 99%

Impact of Water Regimes and Amendments on Inorganic Arsenic Exposure to Rice

Majumder

Biswas⃰

Banik

2021

IJERPH

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Rice-based diet faces an important public health concern due to arsenic (As) accumulation in rice grain, which is toxic to humans. Rice crops are prone to assimilate As due to continuously flooded cultivation. In this study, the objective was to determine how water regimes (flooded and aerobic) in rice cultivation impact total As and inorganic As speciation in rice on the basis of a field-scale trial in the post-monsoon season. Iron and silicon with NPK/organic manure were amended in each regime. We hypothesised that aerobic practice receiving amendments would reduce As uptake in rice grain with a subsequent decrease in accumulation of inorganic As species relative to flooded conditions (control). Continuously flooded conditions enhanced soil As availability by 32% compared to aerobic conditions. Under aerobic conditions, total As concentrations in rice decreased by 62% compared to flooded conditions. Speciation analyses revealed that aerobic conditions significantly reduced (p < 0.05) arsenite (68%) and arsenate (61%) accumulation in rice grains. Iron and silicon exhibited significant impact on reducing arsenate and arsenite uptake in rice, respectively. The study indicates that aerobic rice cultivation with minimum use of irrigation water can lead to lower risk of inorganic As exposure to rice relative to flooded practice.

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Rhizospheric iron and arsenic bacteria affected by water regime: Implications for metalloid uptake by rice

Cited by 45 publications

References 52 publications

Arsenic concentrations and speciation in Australian and imported rice and commercial rice products

Arsenic concentrations and speciation in Australian and imported rice and commercial rice products

Grain Inorganic Arsenic Content in Rice Managed Through Targeted Introgressions and Irrigation Management

Impact of Water Regimes and Amendments on Inorganic Arsenic Exposure to Rice

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