Dataset Information

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

ABSTRACT: 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 ?g kg^-1 under AWD30 and from 28 to 104 ?g kg^-1 under Safe-AWD. TIL grain iAs concentrations for flood treatments across both years ranged from 26 to 127 ?g 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.

SUBMITTER: Fernandez-Baca CP

PROVIDER: S-EPMC7868431 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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

Fernández-Baca Cristina P CP McClung Anna M AM Edwards Jeremy D JD Codling Eton E EE Reddy Vangimalla R VR Barnaby Jinyoung Y JY

Frontiers in plant science 20210125

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 geno ...[more]

PMID: 33569070

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Project description:BACKGROUND:Rice is a global staple crop, being the main calorific component of many people living subsistence livelihoods. Rice can accumulate toxic elements such as arsenic, with the crop water management strongly affecting uptake. This study utilises the Bengal and Assam Aus Panel to conduct genome wide association (GWA) mapping for arsenic in shoots and grains of rice grown over 2 years under continually flooded (CF) and alternate wetting and drying (AWD). The aim was to assess genotype by water management interaction, identify quantitative trait loci (QTL) for arsenic accumulation, and propose candidate genes for lowering grain arsenic. RESULTS:AWD significantly reduced grain arsenic across all cultivars on average by 15.7 and 15.1% in year 1 and 2 respectively and shoot arsenic by 27.0% compared to the plants grown under CF. There was a weak cultivar by treatment interaction for grain for arsenic. All traits were strongly influenced by cultivar. GWA mapping identified a large number of 74 individual QTLs for arsenic, with six QTLs showing stability across years and/or water treatments. Three of the loci (one on chromosome 3, one on chromosome 4, and one on chromosome 5) were investigated in detail using an approach of clustering cultivars that had similar haplotypes for the QTL regions and then looking at the phenotypic values across the clusters. Two of the identified QTLs co-localised with known genes involved in arsenic accumulation, including Lsi2 which has not previously been reported to underlie a grain arsenic QTL. CONCLUSIONS:This study has identified a number of novel QTLs for arsenic accumulation, as well as cultivars that consistently accumulate less arsenic over multiple field traits. The use of a haplotype clustering approach after GWA mapping has allowed for the effect, in terms of arsenic accumulation, to be determined for cultivars that share similar genomic sequence. Allocating nine high yielding Bangladeshi cultivars to these clusters has identified the potential of utilising these QTLs in breeding programmes; for example, incorporation of the QTL on chromosome 5 should decrease grain arsenic in elite high yielding Bangladeshi cultivars by 10% in all high yielding cultivars studied.

Project description:Among nonoccupationally exposed U.S. residents, drinking water and diet are considered primary exposure pathways for inorganic arsenic (iAs). In drinking water, iAs is the primary form of arsenic (As), while dietary As speciation techniques are used to differentiate iAs from less toxic arsenicals in food matrices.Our goal was to estimate the distribution of iAs exposure rates from drinking water intakes and rice consumption in the U.S. population and ethnic- and age-based subpopulations.The distribution of iAs in drinking water was estimated by population, weighting the iAs concentrations for each drinking water utility in the Second Six-Year Review data set. To estimate the distribution of iAs concentrations in rice ingested by U.S. consumers, 54 grain-specific, production-weighted composites of rice obtained from U.S. mills were extracted and speciated using both a quantitative dilute nitric acid extraction and speciation (DNAS) and an in vitro gastrointestinal assay to provide an upper bound and bioaccessible estimates, respectively. Daily drinking water intake and rice consumption rate distributions were developed using data from the What We Eat in America (WWEIA) study.Using these data sets, the Stochastic Human Exposure and Dose Simulation (SHEDS) model estimated mean iAs exposures from drinking water and rice were 4.2 ?g/day and 1.4 ?g/day, respectively, for the entire U.S. population. The Tribal, Asian, and Pacific population exhibited the highest mean daily exposure of iAs from cooked rice (2.8 ?g/day); the mean exposure rate for children between ages 1 and 2 years in this population is 0.104 ?g/kg body weight (BW)/day.An average consumer drinking 1.5 L of water daily that contains between 2 and 3?ng?iAs/mL is exposed to approximately the same amount of iAs as a mean Tribal, Asian, and Pacific consumer is exposed to from rice. https://doi.org/10.1289/EHP418.Among nonoccupationally exposed U.S. residents, drinking water and diet are considered primary exposure pathways for inorganic arsenic (iAs). In drinking water, iAs is the primary form of arsenic (As), while dietary As speciation techniques are used to differentiate iAs from less toxic arsenicals in food matrices.Our goal was to estimate the distribution of iAs exposure rates from drinking water intakes and rice consumption in the U.S. population and ethnic- and age-based subpopulations.The distribution of iAs in drinking water was estimated by population, weighting the iAs concentrations for each drinking water utility in the Second Six-Year Review data set. To estimate the distribution of iAs concentrations in rice ingested by U.S. consumers, 54 grain-specific, production-weighted composites of rice obtained from U.S. mills were extracted and speciated using both a quantitative dilute nitric acid extraction and speciation (DNAS) and an in vitro gastrointestinal assay to provide an upper bound and bioaccessible estimates, respectively. Daily drinking water intake and rice consumption rate distributions were developed using data from the What We Eat in America (WWEIA) study.Using these data sets, the Stochastic Human Exposure and Dose Simulation (SHEDS) model estimated mean iAs exposures from drinking water and rice were [Formula: see text] and [Formula: see text], respectively, for the entire U.S. population. The Tribal, Asian, and Pacific population exhibited the highest mean daily exposure of iAs from cooked rice ([Formula: see text]); the mean exposure rate for children between ages 1 and 2 years in this population is [Formula: see text] body weight (BW)/day.An average consumer drinking 1.5 L of water daily that contains between 2 and [Formula: see text] is exposed to approximately the same amount of iAs as a mean Tribal, Asian, and Pacific consumer is exposed to from rice. https://doi.org/10.1289/EHP418.

Project description:Arsenic (As) in groundwater and its accumulation in agricultural produces has caused serious threats to human health. The majority of current research on As mainly focuses on the technical aspects while bypassing the social perspectives. Farmers are the prime stakeholders as well as executors of agricultural strategies, and their adaptation largely depends on how they perceive the risk for which a mitigation strategy is proposed. This study aims to explore how rice and vegetable farmers perceive As accumulation in their rice and vegetables as well as explore current crop- and body-loading status, the subsequent health consequences of As, and alleviation possibilities with mitigation strategies and to investigate if there is an association between their socioeconomic status and their level of perception. Results reveal that one-fourth of the farmers gave a positive message regarding the As-contamination scenario in rice and vegetables. Although 10 farmers' socioeconomic characteristics were positively significant, distinctive emphasis should be given to five predictor variables explaining 88% variances: knowledge, direct participation in farming, information sources used, participant education, and organizational participation. Path analysis depicts that direct participation in farming presents the highest positive total effect (0.855) and direct effect (0.503), whereas information sources show the highest positive indirect effect (0.624). The mean As content in all five locations was statistically significant at the 5%, 5%, 0.1%, 1%, and 1% probability levels in scalp hairs, rice, vegetables, soils, and irrigation water, respectively. The first principal component (PC1) explains 92.5% of the variation. Significant variations were primarily explained by As levels in irrigation water, rice grain, and soil. Farmers' perception is far behind the actual field status of As level and its transfer. Therefore, intensified priorities should be administered on the farmers' characteristics contributing to variances in perception. The findings can be utilized for policy formulation in all As-endemic nations. More multidisciplinary research can be undertaken on farmers' attitude towards adopting As-mitigation techniques, with a focus on the socioeconomic position found to influence farmers' perceptions.

Dataset Information

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

Publications

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

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