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In the present study, the effects of zinc oxide nanoparticles (ZnO NPs) on rice (Oryza sativa L. cv. PB1509) plant growth were assessed in hydroponics (5, 10, 25, 50 mg L-1) and soil microcosm (5, 10, 25 50 mg kg-1) experiments. In both hydroponics and soil experiments, Zinc (Zn) accumulation in plant parts (roots, shoots and grains) was found to increase with increasing doses of ZnO NPs. Grains accumulated 29 mg kg-1 Zn at 50 mg kg-1 ZnO NPs in the soil experiment. In the hydroponics experiment, growth and photosynthetic pigments were induced by ZnO NPs up to 10 mg L-1, while higher doses of 25 and 50 mg L-1 were toxic to plant growth. Antioxidant enzyme activities (SOD, CAT, APX and GPX) were mostly increased or unaffected by all ZnO NPs doses. In soil experiments, acid and alkaline phosphatase activities were increased at 5 mg kg-1 followed by a declining trend. However, a significant decrease occurred only at 50 mg kg-1. Urease activity in soil was significantly increased at all doses of ZnO NPs, while the activity of dehydrogenase did not show any significant change up to 25 mg kg-1. The length of plants and photosynthetic pigments did not show much toxicity except root length beyond 10 mg kg-1; however, the biomass of plants including grains was significantly lower than control beyond 5 mg kg-1 dose. The activity of antioxidant enzymes (GPX, APX and CAT) showed a significant increase at all doses of ZnO NPs. The DTPA extractable Zn concentration in the soil was significantly elevated with increasing exposure concentrations of ZnO NPs. Based on hydroponics and soil experiments, this study suggests a dose of up to 10 mg L-1 or 10 mg kg-1 would be an appropriate dose for augmenting the growth of rice plants and Zn accumulation, and this can be practically utilized for rice plants growing in submerged conditions. [ABSTRACT FROM AUTHOR]

Arsenic (As) is a major threat to the environment and human health due to its toxicity and carcinogenicity. Occurrence of alarming concentrations of As in water and soil leads to its bioaccumulation in crops which is a major health concern globally. Rice (Oryza sativa) is a staple food for a large population staying in As contaminated areas so, it is of utmost importance to reduce As levels in rice, especially grains. Amongst several strategies in practice, biotechnology may provide an effective option to reduce As accumulation in rice grains. Genetic engineering can be a viable approach to exploit potential genes playing roles in As metabolism pathway in plants. Besides, developing low As accumulating rice varieties through breeding is also an important area. Identifying genotypic variation in rice is a crucial step toward the development of a safe rice cultivar for growing in As-affected areas. Significant genotypic variation has been found in rice varieties for As accumulation in grains and that is attributable to differential expression of transporters, radial oxygen loss, and other regulators of As stress. This review provides recent updates on the research advances leading to transgenic and breeding approaches adopted to reduce As levels in rice, especially grains. Arsenic (As) contamination in water, soil, and crops is creating a difficult situation for the large population across the globe. Various efforts are being made to reduce As levels in rice as it is a staple crop. This review presents recent biotechnological advances toward the development of low As accumulating rice. The review shall be an important information resource for the readers on the topic. [ABSTRACT FROM AUTHOR]

Widespread distribution, toxicity and exposure through rice and rice-based food products make arsenic (As) contamination of environment a serious issue. This review discusses various strategies that can be utilised to tackle the As problem in rice, and the socioeconomic impacts of the As problem. The countries of south and south-east Asia are renowned as hotspots of As contamination owing to occurrence and enrichment of As in soil and groundwater via natural biogeochemical weathering of rocks and As-enriched sediment. The irrigation of rice is mostly applied through the use of contaminated groundwater leading to high As accumulation in rice grains. The intensification of research to address the problem of As in rice has been seen in the past two decades. It has been realised that appropriate irrigation water management, which acts as a major driver of As chemistry in soil and As uptake and transport in plants, can be an easy and affordable solution. Further, balanced supplement of various nutrient elements like selenium (Se), silicon (Si), sulfur (S), nitrogen (N), iron (Fe) and zinc (Zn) has been found to impart dual benefits in terms of reduced As toxicity as well as enhance the nutritional quality of rice grains. Several other agronomic and biotechnological approaches, processing, and cooking methods of rice were found to have profound impacts on rice As and its speciation from farms to table. [ABSTRACT FROM AUTHOR]

The study implements a periodical intermittent water cycle during rice cultivation providing insight potential in minimizing soil bio-available arsenic. Soil As concentrations were 34 ± 0.49 and 72.03 ± 0.54 mg kg-1 As respectively in two selected fields with rice cultivars gosai and satabdi, in comparison to 42.26 ± 0.37 and 83.69 ± 0.48 mg kg-1 in continuously flooded field soil, determined through ICP-MS. The study found higher translocation of silicon from soil to rice plant parts under intermittent irrigation having pH range of 7.6–9.4 and greater availability of soil organic content that in turn release more labile silicon from soil to aqueous phase for plant accumulation. This increased uptake of silicon strengthens rice shoots, nodes and leaf xylem-phloem integrity compared to conventional continuously flooded rice cultivation approach, suppressing the arsenic translocation, as observed under FE-SEM real-time imaging. Fresh plants were analysed for bioaccumulation and translocation factors of arsenic and silicon to justify the enhanced silicon uptake under proposed practice. Plant stress regulator enzymes viz. malondialdehyde (MDA), total protein, superoxide dismutase (SOD), guaiacol peroxidase (GPX) and ascorbate peroxidase (APX) from both conditions and found to be better in intermittent method over conventional practice with higher productivity. Image 1 • Implementation of intermittent irrigation in rice cultivation significantly reduces arsenic accumulation in rice plant. • Dry-wet irrigation practice renders the lesser arsenic mobilization involving soil physico-chemical parameters. • Soil silicon dissolution is enhanced under intermittent dry-wet phase from H 4 SiO 4 bound minerals. • Increased silicon uptake suppresses arsenic translocation and improves rice internal ultra-structure. • Stress markers are lower in silicon rich plants under intermittent irrigation over conventional flooding practice. [ABSTRACT FROM AUTHOR]

Arsenic (As) is a toxic element with the potential to cause health effects in humans. Besides rice is a source of both amino acids (AAs) and mineral nutrients, it is undesired source of As for billions of people consuming rice as the staple food. Selenium (Se) is an essential metalloid, which can regulate As toxicity by strengthening antioxidant potential. The present study was designed to investigate As III stress mitigating effect of Se VI in rice. The level of As, thiolic ligands and AAs was analyzed in rice seedlings after exposure to As III /Se VI alone and As III +Se VI treatments. Selenate supplementation (As III 25 μM+Se VI 25 μM) decreased total As accumulation in both root and shoot (179 & 144%) as compared to As III alone treatment. The As III +Se VI treatment also induced the levels of non-protein thiols (NPTs), glutathione (GSH) and phytochelatins (PCs) as compared to As III alone treatment and also modulated the activity of enzymes of thiol metabolism. The content of amino acids (AAs) was significantly altered with Se VI supplementation. Importantly, essential amino acids (EAAs) were enhanced in As III +Se VI treatment as compared to As III alone treatment. In contrast, stress related non-essential amino acids (NEAAs) like GABA, Glu, Gly, Pro and Cys showed enhanced levels in As III alone treatment. In conclusion, rice supplemented with Se VI tolerated As toxicity with reduced As accumulation and increased the nutrition quality by increasing EAAs. [ABSTRACT FROM AUTHOR]

Arsenic (As) is a non-essential element whose entry into rice grains is an issue of public concern. The need, therefore, exists to understand the regulatory mechanisms of As accumulation and distribution patterns in plants. This study analyzed the effect of sulfur (S) supply on As accumulation and distribution in rice ( Oryza sativa L. var. IR64) plants. Nine day old seedlings were grown in 0.798 mM S (Normal S), 0.2 mM S (Low S) and 0.003 mM S (Zero S) for 7 days and then subjected to AsIII (20 μM) exposure for 7–15 days. The concentration of As varied significantly in different S treatments with a consistent trend of decrease in As concentration in depleted S supply treatments on both 7 days and 15 days. Arsenic concentration declined from 726 μg g − 1 DW to 537 μg g − 1 DW in roots and from 29 μg g − 1 DW to 8 μg g − 1 DW in shoots at 7 days, and from 1536 μg g − 1 DW to 1062 in roots and from 58 μg g − 1 DW to 16 μg g − 1 DW in shoots at 15 days, when S supply declined from normal to zero. The subcellular distribution of As was also found to vary with alteration in S supply and also differentially in shoot and root. In general, an up-regulation of sulfate transporters of groups 1 and 2 was observed while As transporters (Lsi1 and Lsi2) were down-regulated in response to As exposure to maintain sulfate and to regulate As levels. In spite of S depletion, an increase in cysteine, glutathione (GSH) and phytochelatin (PC) levels was observed upon As exposure. However, some negative impact of S depletion and As could be seen on the growth of plants. The study concluded that even in conditions of decreased S availability, plants continue to rely on thiol metabolism to tackle As levels and its toxicity effectively and altered subcellular distribution of As contributes only partially. [ABSTRACT FROM AUTHOR]

The present study analyzed the effects of individual microbes and their consortium (Priestia endophytica NDAS01F , Bacillus licheniformis NDSA24R, and P. flexa NDAS28R) either alone or in interaction with thiourea (TU) on growth and responses of rice plants subjected to As stress (50 mg kg−1 in soil) in a pot experiment. The bacteria used in the experiment were isolated from As contaminated fields of Nadia, West Bengal and showed significant As removal potential in in vitro experiment. The results revealed significant growth improvement, biomass accumulation, and decline in malondialdehyde levels in rice plants in bacterial and TU treatments as compared to control As treatment. The best results were observed in a bacterial consortium (B1-2-3), which induced a profound increase of 65%, 43%, 127% and 83% in root length, shoot length, leaf width and fresh weight, respectively. Sulfur metabolism and cell wall synthesis were stimulated upon bacterial and TU amendment in plants. The maximum reduction in As concentration was observed in B2 in roots (−55%) and in B1-2-3 in shoot (−83%). The combined treatment of B1-2-3 + TU proved to be less effective as compared to that of B1-2-3 in terms of As reduction and growth improvement. Hence, the usage of bacterial consortium obtained in the present work is a sustainable approach, which might find relevance in field conditions to achieve As reduction in rice grains and to attain higher growth of plants without the need for additional TU supplementation. [Display omitted] • Bacteria isolated from Nadia, West Bengal were used for consortium. • Bacterial consortium promoted growth of plants and reduced arsenic concentration. • Arsenic translocation from root to shoot was significantly decreased. • Bacterial consortium + thiourea did not result in synergistic effects on growth. • Bacterial consortium + thiourea did not cause additional arsenic reduction. [ABSTRACT FROM AUTHOR]

The adverse effects of arsenic (As) contamination are well known. Rice is a staple food for 50% of the world population but the accumulation of As into rice hampers the food security and safety. Thus the amelioration of As stress and reduction of As levels in rice are needed. In this study, transcriptome (Illumina sequencing) and proteome (2D gel electrophoresis) explored mechanisms of consortium (P. putida+C. vulgaris) mediated growth promotion and As amelioration in rice. The rice seedlings grown hydroponically in the Hewitt nutrient medium and after acclimatization, exposed to 50 µM As alone as well as with microbial consortium to observe the impact at morphological and molecular level. The inoculation of microbial consortium significantly ameliorated the As toxicity, improved growth of root hairs and maintained cellular integrity of the epidermis, exodermis and the stele region during As exposure. Several genes showed differential expression in As and As+ P. putida. Down-regulation of As transporters (OsPIP2;2 and OsPIP2;3, OsTIP2;1) and higher expression of WRKY gene (WRKY28) during As+ P. putida + C.vulgaris suggested reduction of As uptake in rice. The up-regulation of nutrient elements transporters (OsZIFL9, OsZIFL5, OsZIFL12 and OsZIP2, OsYSL15 and OsCOPT6) in the presence of consortium indicated the improved nutrient status of rice. Higher expression of regulatory elements like auxin/indole 3 acetic acid (AUX/IAA), WRKY and myeloblastosis (MYB) TFs and down-regulation of defense responsive genes such Glutathione-S-transferase, Peroxidase and Glutaredoxinduring As+ P. putida + C.vulgaris exposure was also observed. Proteome profiling demonstrated differential abundance of proteins involved in photosynthesis (chlorophyll a/b binding protein, photosystem I Fe-S centre), energy metabolism (ATP synthase subunit beta) transport, signaling (tubulin 1, actin 1), defense (glutathione S-transferase, phenylalanine ammonia lyase) and amino acid metabolism (cysteine synthase, glutamine synthetase), which supported the As ameliorative and growth-promoting potential of microbial consortium during As stress in rice plants. The study gives comprehensive information about gene and protein changes in rice plants in As+consortium exposure. [Display omitted] • P.putida + C.vulgaris ameliorated arsenic toxicity by modulating the defensive pathways. • P.putida + C.vulgaris efficient to modulate transcription factors which provide tolerance by reducing As uptake. • P.putida + C.vulgaris modulated the expression of transporters. • Rice with high nutritional value during As exposure achieved through P.putida + C.vulgaris. [ABSTRACT FROM AUTHOR]

The physiological, biochemical, and proteomic changes in germinating rice seedlings were investigated under arsenic stress. A marked decrease in germination percentage, shoot, and root elongation as well as plant biomass was observed with arsenic treatments, as compared to control, whereas accumulation of arsenic and malondialdehyde (MDA) in seedlings were increased significantly with increasing arsenic concentration (both AsIII and AsV). The up-regulation of some antioxidant enzyme activities and the isozymes of superoxide dismutase (SOD, EC 1.15.1.1), ascorbate peroxidase (APX, EC 1.11.1.11), peroxidase (POD, EC 1.11.1.7), and glutathione reductase (GR, 1.6.4.2) substantiated that arsenic accumulation generated oxidative stress, which was more pronounced in As(III) treatment. We also studied the protective effect of reduced glutathione (GSH) and cysteine (Cys) to As(III)/As(V) stressed seedlings. Both GSH and Cys imparted enhanced tolerance to seedlings against arsenic stress. Seedlings growth improved while level of MDA declined significantly when GSH and Cys were supplemented to As(III)/As(V) treatments suggesting GSH and Cys-mediated protection against oxidative stress. The arsenic content was highest in roots of seedlings grown in As(III) in the presence of GSH/Cys. However, in case of As(V) plus GSH or Cys, the arsenic content in seedlings was highest in shoots. The results are suggestive of differential metabolism of As(III) and As(V) in rice. [Copyright &y& Elsevier]

Tonoplast Intrinsic Proteins (TIPs) are vital in transporting water and solutes across vacuolar membrane. The role of TIPs in the arsenic stress response is largely undefined. Rice shows sensitivity to the arsenite [As[III]] stress and its accumulation at high concentrations in grains poses severe health hazards. In this study, functional characterization of OsTIP1;2 from Oryza sativa indica cultivar Pusa Basmati-1 (PB-1) was done under the As[III] stress. Overexpression of OsTIP1;2 in PB-1 rice conferred tolerance to As[III] treatment measured in terms of enhanced shoot growth, biomass, and shoot/root ratio of overexpression (OE) lines compared to the wild-type (WT) plants. Moreover, seed priming with the IRW100 yeast cells (deficient in vacuolar membrane As[III] transporter YCF1) expressing OsTIP1;2 further increased As[III] stress tolerance of both WT and OE plants. The dithizone assay showed that WT plants accumulated high arsenic in shoots, while OE lines accumulated more arsenic in roots than shoots thereby limiting the translocation of arsenic to shoot. The activity of enzymatic and non-enzymatic antioxidants also increased in the OE lines on exposure to As[III]. The tissue-specific localization showed OsTIP1;2 promoter activity in root and root hairs, indicating its possible root-specific function. After As[III] treatment in hydroponic medium, the arsenic translocation factor (TF) for WT was around 0.8, while that of OE lines was around 0.2. Moreover, the arsenic content in the grains of OE lines reduced significantly compared to WT plants. [Display omitted] • The overexpression of OsTIP1;2 induced resilience in the rice plants against the As[III] stress. • Seed priming with OsTIP1;2 expressing IRW100 yeast increased As[III] tolerance of overexpressed (OE) lines of rice. • The overexpression of OsTIP1;2 reduced arsenic translocation factor (TF) in rice. • The overexpression of OsTIP1;2 reduced arsenic content in rice grains. [ABSTRACT FROM AUTHOR]

• TIP1;1, TIP1;2, TIP2;2, TIP3;1 , and TIP4;1 were cloned from Oryza sativa ssp. indica cultivar IR-64. • In silico analysis of the cloned genes strongly support their identity as member of TIPs. • Cloned TIPs showed differential regulation pattern in various tissues and abiotic stress response. Tonoplast Intrinsic Proteins (TIPs) constitute a significant class of the aquaporins. The TIPs control water trade among cytosolic and vacuolar compartments and can also transport glycerol, ammonia, urea, hydrogen peroxide, metals/metalloids, and so forth. Additionally, TIPs are engaged with different abiotic stress responses and developmental processes like leaf expansion, root elongation and seed germination. In this study, ten TIP genes in the rice genome were identified from Oryza sativa ssp indica. Among these, representative groups of TIP genes were cloned and sequenced whilst some TIP sequences showed stop codons in the coding region. The secondary structure analysis represented six conserved transmembrane helices along with the inter-helical regions having conserved motifs. The representative three-dimensional tetrameric design of protein sequence of TIP1;1 displayed key features like NPA motifs, aromatic/arginine (ar/R) selectivity filters, and Froger's residues. The vacuolar localization, transmembrane topological properties, and conserved motif analysis of the cloned genes altogether supported their identity as TIPs. An unrooted phylogenetic tree delineated the relatedness of TIPs from Oryza with different species and bunched them into five clades. The promoter analysis uncovered key regulons associated with administering abiotic stress responses. Gene expression studies showed that TIPs are differentially regulated under salt and drought stress at various time points in shoots and roots of rice. Also, the pattern of expression was found to be significantly variable in five different rice tissues. The heat-map based tissue and stress- specific expression analysis supported the experimental findings. In conclusion, the identification and transcript-level expression studies of TIPs significantly contribute towards the comprehension of their utilitarian significance in the abiotic stress response. [ABSTRACT FROM AUTHOR]

Highlights • The major source of arsenic exposure in human is rice and rice-based products. • Apart from rice, As levels in other important dietary sources has also been covered. • The level of As species (iAs/oAs) influences the associated As toxicity in food. • It is mandatory to set the regulatory limits of arsenic in food at earliest. Abstract Arsenic (As) is a carcinogenic element threatening the health of millions of people around the world. The sources for human exposure include drinking water, crops, processed food items, vegetables, mushrooms, animal products etc. The people at most risk are those living in hotspots of As contamination viz., Bangladesh and West Bengal, India. However, it has been found that rice growing in other uncontaminated regions like Australia can also contain high As levels. Further, rice import/export among various countries make the problem of global concern. The emergence of several reports of As in rice based food products including baby food from different parts of the world demonstrates that even the infants and toddlers are not spared. The variation in the levels of inorganic and organic As species in different food items influence the associated As toxicity. This review tries to present the available data on As levels in various dietary sources. [ABSTRACT FROM AUTHOR]

In the present study, arsenic (As) toxicity amelioration potential of a consortium of plant growth promoting rhizobacterium ( Pseudomonas putida ) and alga ( Chlorella vulgaris ) was evaluated during arsenate (AsV) exposure to rice ( Oryza sativa ) plants for 15 d. The consortium mediated amelioration of As toxicity was evident through improved growth of rice plants (root and shoot length and biomass) and reduced oxidative stress [as level of superoxide radicals (O 2 − ), hydrogen peroxide (H 2 O 2 ) and membrane damage]. The positive responses were attributable to a significant decline in As accumulation in root (94 mg kg −1 dw) and shoot (51 mg kg −1 dw) in consortium ( P. putida  +  C. vulgaris ) inoculated seedlings as compared to As alone exposed plants (156 and 98 mg kg −1 dw, respectively). There were also significant changes in the level of various nutrient elements (Mn, Fe, Co, Zn, Mo and Cu), thiols and in the activities of antioxidant and thiol metabolism enzymes in the consortium inoculated seedlings that allowed the plants to tolerate As stress effectively and achieve better growth. The study demonstrated that consortium of P. putida and C. vulgaris may alleviate As stress and improve growth of rice seedlings along with reduction in As levels. [ABSTRACT FROM AUTHOR]

Thiourea (TU) is a chemo-priming agent and non-physiological reactive oxygen species (ROS) scavenger whose application has been found to reduce As accumulation in rice grains along with improved growth and yield. The present field study explored TU-mediated mechanistic changes in silicon (Si) assimilation in root/shoot, biochemical and molecular mechanisms of arsenic (As) stress amelioration in rice cultivars. Gosai and Satabdi (IET-4786) rice cultivars were selected for field experiment at three different places; control field and two other As contaminated experimental fields (EF1 and EF2) in West Bengal, India. The average As reduction was observed to be 9.5% and 19.8% whereas the yield increment was 8.8% and 17.7% for gosai and satabdi, respectively among all the three experimental fields. The positive interrelation was also observed between improved internal ultrastructure anatomy and enhanced Si assimilation (36%–423%) upon TU application. The level of photosynthetic pigments was increased by 29.8%–99.2%. Further, activities of antioxidant enzymes were harmonically altered in TU supplemented plants. The expression of various As related transporter genes in flag leaf and developing grains (inflorescence) was changed in both the rice cultivars (gosai and satabdi). It was also presumably responsible for observed As reduction in grains. Thus, TU application was found to be an efficient and sustainable agronomic practice for amelioration of As toxicity in rice plants in As contaminated field conditions. [Display omitted] • Thiourea reduced 9.5% and 19.8% grain arsenic in gosai and satabdi respectively. • Thiourea improved pigment content and reduced oxidative stress in rice cultivars. • Thiourea improved ultrastructure anatomy by enhanced silica assimilation in rice. • Thiourea reduced As in rice cultivars through modulation in gene expressions. [ABSTRACT FROM AUTHOR]

Abstract: Recent breakthroughs in rice arsenic (As) research demonstrate that As accumulation significantly affects trace nutrients in rice grain. In the present study we analyzed the amino acid (AA) profile of sixteen rice genotypes differing in grain As accumulation, grown at three sites with different soil As concentrations, in ascending order, Chinsurah

The present study delineates the interactions of arsenic (As), a carcinogenic metalloid, and thiourea (TU), a non-physiological reactive oxygen species (ROS) scavenger, in rice plants grown in As contaminated fields in West Bengal, India. The study was performed for four consecutive seasons (two boro and two aman) in 2016 and 2017 with two local rice cultivars; Gosai and Satabdi (IET-4786) in a control and two As contaminated experimental fields. Thiourea (0.05% wt/vol) treatment was given in the form of seed priming and foliar spray. Thiourea significantly improved growth and yield of rice plants and reduced As concentration in root, shoot, husk and grains in both cultivars and fields. The reduction in As concentration ranged from 10.3% to 27.5% in four seasons in different fields. The average (four seasons) increase in yield was recorded about ~8.1% and ~11.5% in control, ~20.2% and ~18.6% in experimental field 1, and ~16.2% and ~24.1% in experimental field 2, for gosai and satabdi, respectively. Mean hazard quotient (HQ) and incremental lifetime cancer risk (ILCR) values of As reduced upon TU supplementation for both cultivars as compared to that of non-TU plants. Hence, TU can be effectively used to cultivate rice safely in As contaminated fields. ga1 • Rice plants were grown in arsenic contaminated fields in two year study. • Thiourea treatment was given as seed priming and foliar spray. • Thiourea mitigated arsenic stress and improved growth of rice pants. • Arsenic concentration in rice grains reduced ranged from ~10.3% to ~27.5%. • The average yield of rice plants increased ranged from ~8.1% to ~24.1%. [ABSTRACT FROM AUTHOR]

• Rice grains and rice based food products were analyzed for As, Zn, Cu and Fe. • Arsenic concentration showed a range of 0.04 – 0.45 μg g-1 in rice grains. • Hazard Quotient was found to be >1 for rice grains in all cities. • The carcinogenic risk of As for rice grains was higher than acceptable safe limit. • Rice consumption may not provide daily recommended Fe to people in most cities. The present study measured arsenic (As), copper (Cu), zinc (Zn) and iron (Fe) concentrations in grains of different rice varieties and rice based food products collected from various cities located in Gangetic basin in India. Total 44 rice samples were collected from local markets from different locations and analyzed for elemental concentrations by Atomic Absorption Spectroscopy. The results showed that the mean concentration of As, Zn, Cu and Fe were 0.15 ± 0.10, 117 ± 24, 4.6 ± 0.5 and 32.5 ± 5.7 μg g-1 dw, respectively in rice grains and 0.17 ± 0.09, 193 ± 241, 4.5 ± 1.0 and 45.7 ± 25 μg g-1 dw, respectively in rice based food products. The hazard quotient (HQ) of As was the lowest in Patna (2.4) and the highest in Kolkata (5.0) but it was always higher than threshold value of one. The carcinogenic risk of the As for rice grains was found to be higher (10-3) than safe range of 10-6-10-4 set by USEPA except Jabalpur. Daily consumption analyses also indicated that consumption of rice and rice products was not sufficient to fulfill daily requirement of Fe in most of the cities. The present results implicate that the consumption of rice and rice products may act as source of As on one hand and may not provide sufficient essential elements on the other. [ABSTRACT FROM AUTHOR]

• RNA Seq. and protein profiling presented new dimensions of Se mediated As tolerance. • Se ameliorated As toxicity by modulating Lsi1, NIP1;1, NRAMP and ABCG transporters. • Up-regulation of GST, PRX, GRX and HSPs suggested amelioration of oxidative stress. • Se provided As tolerance through TFs e.g. , MYB, WRKY, AUX/IAA responsiveness. • Omics approaches established comprehensive verification of As-Se responsive proteins. Arsenic (As), a chronic poison and non-threshold carcinogen, is a food chain contaminant in rice, posing yield losses as well as serious health risks. Selenium (Se), a trace element, is a known antagonist of As toxicity. In present study, RNA seq. and proteome profiling, along with morphological analyses were performed to explore molecular cross-talk involved in Se mediated As stress amelioration. The repair of As induced structural deformities involving disintegration of cell wall and membranes were observed upon Se supplementation. The expression of As transporter genes viz., NIP1;1, NIP2;1, ABCG5, NRAMP1, NRAMP5, TIP2;2 as well as sulfate transporters, SULTR3;1 and SULTR3;6, were higher in As + Se compared to As alone exposure, which resulted in reduced As accumulation and toxicity. The higher expression of regulatory elements like AUX/IAA, WRKY and MYB TFs during As + Se exposure was also observed. The up-regulation of GST, PRX and GRX during As + Se exposure confirmed the amelioration of As induced oxidative stress. The abundance of proteins involved in photosynthesis, energy metabolism, transport, signaling and ROS homeostasis were found higher in As + Se than in As alone exposure. Overall, present study identified Se responsive pathways, genes and proteins involved to cope-up with As toxicity in rice. [ABSTRACT FROM AUTHOR]