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A novel laboratory model was designed to study the arsenic (As) biotransformation potential of the microalgae Chlorella vulgaris and Nannochloropsis sp. and the cyanobacterium Anabaena doliolum. The Algae were treated under different concentrations of As(III) to check their growth, toxicity optimization, and volatilization potential. The results revealed that the alga Nannochloropsis sp. was better adopted in term of growth rate and biomass than C. vulgaris and A. doliolum. Algae grown under an As(III) environment can tolerate up to 200 µM As(III) with moderate toxicity impact. Further, the present study revealed the biotransformation capacity of the algae A. doliolum, Nannochloropsis sp., and Chlorella vulgaris. The microalga Nannochloropsis sp. volatilized a large maximum amount of As (4,393 ng), followed by C. vulgaris (4382.75 ng) and A. doliolum (2687.21 ng) after 21 days. The present study showed that As(III) stressed algae-conferred resistance and provided tolerance through high production of glutathione content and As-GSH chemistry inside cells. Thus, the biotransformation potential of algae may contribute to As reduction, biogeochemistry, and detoxification at a large scale.

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Rapeseed, the second-most-important vegetable oil source, is cultivated in various areas of India where both groundwater and soil are contaminated with fluoride (F-). Furthermore, the frequent use of F- contaminated groundwater for irrigation leads to accumulation of F- in surface and sub-surface soil. The study aims to compare the morphological and biochemical changes in Brassica juncea L., the variations in its fatty acids (FAs) composition and oil yield, under two regimes of F- contaminated soils: (i) pre-contaminated soil (Tr) and (ii) irrigation with F- contaminated water (Ir). The level of F- (µg g-1) in the plant tissues (root, leaf, and grain) was significantly higher in Ir_10 (18.3, 14.7, and 2.8, respectively) than in Tr_10 (4.3, 2.6, and 0.77, respectively), while the oil yield was significantly lower with Ir_10 (19.5%) than with Tr_10 (44.9%). The phytoremediation potential of F- by Brassica juncea L. is greater in Tr regime than in the Ir regime. The erucic acid content (%), which is detrimental to cardiac health, increased to 67.37% (Ir_10) and 58.3% (Tr_10) from 57.73% (control). Thus, the present study shows that irrigation with F- contaminated water results in greater toxicity and accumulation in plants and is not safe for human health.

Irrigation with F^­ contaminated water results in a greater accumulation of F^­ in mustard than cultivated on pre-contaminated soil. The level of erucic acid in mustard oil enhances against F^­ exposure.

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Fluoride (F-) contamination in groundwater of Unnao district, Uttar Pradesh was reported for the first time in 1994, however comprehensive monitoring of F- in different environmental matrices remains to be undertaken. The presented study reports spatio-temporal monitoring of F- content in groundwater, crops and soil from F- affected district Unnao, in pre-monsoon (PRM), monsoon (MO) and post-monsoon (PMO), to establish F- groundwater-soil-plant continuum. More than 80% of groundwater samples were contaminated with F-> 1.0 mg L-1 with highest level (mg L-1), at Patiyara (3.6 ± 0.64), during PRM > Pathakpur (2.73 ± 0.57) during PMO > Sarukheda (2.40 ± 0.43) during PRM. High Cr in groundwater was observed in Jajmau (7.08 ± 1.42). The level of F- (mg Kg-1) in agricultural soils followed 3.4 ± 0.71 at Patiyara (MO) > 2.9 ± 0.14 at Badlikheda (PRM) 1.89 ± 0.28 at Jagatkhera (PRM). Among the different edible parts of crops in selected sites, highest F- content (mg Kg-1), F- level in grains of Oryza sativa ranged between 0.23 ± 0.02 to 2.01 ± 0.24. Whereas in the edible fruit of Trichosanthes diocia contained 1.47 ± 0.32 and Momordica charantia 1.47 ± 0.02. Leaf of spinach (1.03 ± 0.22) and seed of Brassica juncea (0.73 ± 0.08). Overall, comparing across all the three seasons, level of F- was highest in all the plants during MO, as compared to PRM and PMO. The regression analysis of physiochemical properties of groundwater show negative relationship between Na+ and F- whereas soil alkalinity exhibited strong influence in soil F-. The high F- content in soil and groundwater at Patiyara and Shekhpur also coincided with presence of several brick kilns, possibly contributing to the high F-.

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A comparative assessment of the phytoremediation efficiency of two tolerant grass species viz. vetiver and lemongrass were performed in pots against simulated Ni-Cd battery electrolyte waste (EW) contaminated soil (EW1%, EW2% and EW4% w/w). Ni (µg g-1) accumulation was higher in shoots (36.8) and roots (252.9) of vetiver than in lemongrass (12.5 and 79.7, respectively). While the same trend was true for Cd (µg g-1) accumulation in vetiver and lemon grass roots (232.2 and 147.2, respectively), however, the accumulation in vetiver shoot (43.4) was less than in lemongrass (99.9). The bioaccumulation factor of metals in both grasses increased with EW contamination. Vetiver was tolerant towards EW toxicity than lemongrass, as it exhibited lesser decline in morphological parameters, lesser rise in TBARS against the doses of EW. The activities of SOD, APX, POD enzymes were higher in vetiver whereas, only GR in lemongrass. Multiple linear regression model show, pH had strong and positive influence over the Ni and Cd uptake by the plants whereas, phosphate, OM and bioavailable metals influenced negatively. The higher R2 (>0.9) and Chi-square values ≤ 1 in sigmoid non-linear model demonstrates robustness of the model for predicting the Ni and Cd accumulation (MHM) in both the grasses. Ni accumulation was higher than Cd, roots had greater accumulation of heavy metal and vetiver was a greater accumulator of Ni and Cd from EW the contaminated soil than lemongrass.

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The present study investigates the role of Chlorella sp. in the mitigation of arsenic (iAs) induced toxicity in Oryza sativa L. The study shows, co-culture of rice seedlings with Chlorella sp. reduced the iAs accumulation, simultaneously improving the growth of seedlings under iAs treatments. While treatment with As(III) and As(V) (60 µM) alone, inflicted toxicity in rice seedlings, manifested as significant enhancement in stress markers levels (TBRAS and H2O2), this coincided with the shifting of cellular reduced state to oxidized state (reduced GSH/GSSG ratio). Contrarily, co-culturing rice seedlings with Chlorella sp. under iAs toxicity, reduced these stress markers and recovered the GSH/GSSG ratio. The GSH dependent antioxidant enzymes i.e. GR and GPX activities also exhibited significant enhancement upon co-culturing rice seedlings with Chlorella sp. against iAs stress. Simultaneously, the expression of four thiol dependent GRX genes, i.e. GRX13950, GRX35340, GRX12190 and GRX07950 were enhanced against As(III) and As(V) (60 µM), which reduced upon co-culturing with Chlorella sp. A similar trend was also observed with the expression of GST genes, where the co-culture with Chlorella sp. significantly reduced the genes expression of two isoforms (GST 38600 and GST 38610). On the contrary, the expression of S-adenosylmethionine dependent methyltransferases (SAMT) gene in rice seedlings was enhanced upon co-culturing with the Chlorella sp. against iAs stress. Overall, the results demonstrate that the rice seedlings when co-culture with Chlorella sp. ameliorates iAs toxicity through GSH dependent detoxification pathway, evident from the enhanced expression of GRX, GST, SAMT genes and activity of GSH dependent antioxidant enzymes (GR and GPX) in the rice seedlings.

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Heavy metals are ubiquitously present in nature, including soil, water, and thus in plants, thereby causing a potential health risk. This study has investigated the role and efficiency of the chickpea metallothionein 1 (MT1) gene against the major toxic heavy metals, i.e., As [As(III) and As(V)], Cr(VI), and Cd toxicity. MT1 over-expressing transgenic lines had reduced As(V) and Cr(VI) accumulation, whereas Cd accumulation was enhanced in the L3 line. The physiological responses (WUE, A, Gs, E, ETR, and qP) were noted to be enhanced in transgenic plants, whereas qN was decreased. Similarly, the antioxidant molecules and enzymatic activities (GSH/GSSG, Asc/DHA, APX, GPX, and GRX) were higher in the transgenic plants. The activity of antioxidant enzymes, i.e., SOD, APX, GPX, and POD, were highest in the Cd-treated lines, whereas higher CAT activity was observed in As(V)-L1 and GRX in Cr-L3 line. The stress markers TBARS, H2O2, and electrolyte leakage were lower in transgenic lines in comparison to WT, while RWC was enhanced in the transgenic lines, and the transcript of MT1 gene was accumulated in the transgenic lines. Similarly, the level of stress-responsive amino acid cysteine was higher in transgenic plants as compared to WT plants. Among all the heavy metals, MT1 over-expressing lines showed a highly increased accumulation of Cd, whereas a non-significant effect was observed with As(III) treatment. Overall, the results demonstrate that Arabidopsis thaliana transformed with the MT1 gene mitigates heavy metal stress by regulating the defense mechanisms in plants. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s12298-021-01103-1.

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The deterioration of water quality of river Ganga is a huge concern for Govt. of India. Apart from various pollution sources, the religious and ritualistic activities also have a good share in deteriorating Ganga water quality. Thus, the aim of the present study was to evaluate the changes in physico-chemical properties, microbial diversity and role of bacteriophages in controlling bacterial population of Ganga water during mass ritualistic bathing on the occasion of Maha-Kumbh in 2013. The BOD, COD, hardness, TDS and level of various ions significantly increased, while DO decreased in Ganga water during Maha-Kumbh. Ganga water was more affluent in trace elements than Yamuna and their levels further increased during Maha-Kumbh, which was correlated with decreased level of trace elements in the sediment. The bacterial diversity and evenness were increased and correlated with the number of devotees taking a dip at various events. Despite enormous increase in bacterial diversity during mass ritualistic bathing, the core bacterial species found in pre-Kumbh Ganga water were present in all the samples taken during Kumbh and post-Kumbh. In addition, the alteration in bacterial population during mass bathing was well under 2 log units which can be considered negligible. The study of bacteriophages at different bathing events revealed that Ganga was richer with the presence of bacteriophages in comparison with Yamuna against seven common bacteria found during the Maha-Kumbh. These bacteriophages have played a role in controlling bacterial growth and thus preventing putrefaction of Ganga water. Further, the abundance of trace elements in Ganga water might also be a reason for suppression of bacterial growth. Thus, the current study showed that Ganga has characteristic water quality in terms of physico-chemical property and microbial diversity that might have a role in the reported self-cleansing property of Ganga; however, the increased pollution load has surpassed its self-cleansing properties. Since water has been celebrated in all cultures, the outcome of the current study will not only be useful for the policy maker of cleaning and conservation of Ganga but also for restoration of other polluted rivers all over the world.

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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.

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γ-aminobutyric acid (GABA) is a free amino acid, which helps to counteract biotic and abiotic stresses in plants. In the present study, two concentrations of GABA, i.e., 0.5 mM and 1 mM were applied to examine the tolerance of rice seedlings against As(III) (25 µM) toxicity, through the modulations of fatty acids (FAs), stress responsive amino acids (AAs) and polyamines (PAs) biosynthesis. Exogenous GABA (0.5 mM) application significantly reduced the H2O2 and TBARS levels and recovered the growth parameters against As(III) stressed rice seedlings. Simultaneously, co-application of GABA (0.5 and 1 mM) and As(III), consistently enhanced the level of unsaturated fatty acids (USFA) (cis-10-pentadecanoic acid, oleic acid, α-linolenic acid and γ-linolenic acid), which was higher than saturated fatty acid (SFA). Among the USFAs, level of linolenic acid was found to be always higher with GABA application. Similarly, elevated level of AAs (proline, methionine, glutamic acid and cysteine) was also observed with the application of GABA (0.5 and 1 mM) in As(III) stressed seedlings. GABA also enhanced the expression of genes involved in the polyamine synthesis pathway namely arginine decarboxylase (AD), spermine (SPM) and spermidine (SPD) synthase against As(III) treatments, which was higher in roots than in shoots, resulting in enhanced root PAs level. Contrarily, the expression of S-adenosylmethionine decarboxylase (S-AMD) was significantly higher in shoots. Among all the PAs, level of putrescine (PUT) was found to be highest with GABA application. Overall, the study demonstrates that GABA (0.5 mM) at lower concentration plays a vital role in As(III) tolerance by enhancing the biosynthesis of USFA, AA and PA, reducing the level of TBARS and H2O2 in rice seedlings.

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Drought is one of the major abiotic stresses which negatively affect plant growth and crop yield. Metallothionein (MTs) is a low molecular weight protein, mainly involved in metal homeostasis, while, its role in drought stress is still to be largely explored. The present study was aimed to investigate the role of MT gene against drought stress. The chickpea MT based on its up-regulation under drought stress was overexpressed in Arabidopsis thaliana to explore its role in mitigation of drought stress. The total transcript of MT gene was up to 30 fold higher in transgenic lines. Arabidopsis plants transformed with MT gene showed longer roots, better efficiency of survival and germination, larger siliques and higher biomass compared to WT. The physiological variables (A, WUE, G, E, qP and ETR) of WT plants were reduced during drought stress which recovered in transgenic Arabidopsis lines. The enzymatic and non-enzymatic antioxidant (APX, GPX, POD, GR, GRX, GST, CAT, MDHAR, ASc and GSH) levels were also enhanced in transgenic lines to provide tolerance. Simultaneously, drought responsive amino acids, i.e. proline and cysteine contents were higher in transgenic lines. Overall, the results suggest that MT gene is actively involved in the mitigation of drought stress and could be the choice for genetic engineering strategy to overcome drought stress.

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Fluorine is an essential element required in trace amounts but gets toxic for human beings at levels more than 1.5 mg F- L-1 primarily through drinking contaminated water. It is the 13th most abundant element and constitutes about 0.06-0.09% in the earth crust. It is electronegative in aqueous medium forming fluoride ion (F-). Fluoride contamination in the environment occurs mostly due to anthropogenic and geogenic sources. Fluoride is widely distributed in all components of environment, air (0.1-0.6 µg L-1) soils (150-400 mg Kg-1) rocks (100-2000 mg Kg-1), plant (0.01-42 mg Kg-1) and water (1.0-38.5 mg L-1). Human beings and animals are being exposed to F- primarily from water (0.2-42.0 mg L-1) and plants (0.77-29.5 µg g-1). Fluorosis, a health hazard due to F- is a major problem in many countries across the world affecting about 200 million people globally. In India, > 62 million people in twenty states are facing problem due to F-. The most affected states are Rajasthan (7670 habitations), Telangana (1,174 habitations) and Karnataka (1122 habitations). To mitigate this problem, there is an urgent need to understand the current status and brief knowledge of F- geochemistry. The objective of this review is to highlight different sources of F- that contaminate different environmental matrices including plants, the extent of contamination level in India, uptake, translocation and toxicity mechanism in plants. The review also highlights currently available mitigation methods or technologies through physio-chemical and biological means.

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The present study was intended to investigate the role of algae, Anabaena sp. in the amelioration of As toxicity, when co-cultured with rice seedlings. The reduction of growth in rice seedlings against As(III) and As(V) was recovered with Anabaena sp. The Anabaena sp. also reduced the accumulation of As, where it was more efficient against 60µM As(III) (49%) than As(V) (23%) in rice shoot. Similarly, with reduction of As accumulation, lower silicon transporters (Lsi-1 and Lsi-2) was found to be suppressed against As treatments. However, the expression of two nitrogen dependent genes i.e., NR and SAMT were found to be enhanced with the Anabaena sp. Likewise, the activity of antioxidant enzyme, GST, was enhanced, whereas, the activity of other enzymes such as SOD, APX, GPX, GR and DHAR were decreased with As+Algae combinations. Overall, the result suggested that the Anabaena sp. reduces As accumulation, modulates gene expressions and antioxidants to ameliorate the As toxicity in Oryza sativa L.

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The present study was intended to investigate the role of amino acid glycine in detoxification of As in Oryza sativa L. The growth parameters such as, shoot length and fresh weight were decreased during As(III) and As(V) toxicity. However, the application of glycine recovered the growth parameters against As stress. The application of glycine reduced the As accumulation in all the treatments, and it was more effective against As(III) treatment and reduced the accumulation by 68% in root and 71% in shoot. Similarly, the translocation of As from root to shoot, was higher against As(III) and As(V) treatments, whereas, reduced upon glycine application. The translocation of Fe and Na was also affected by As, which was lower under As(III) and As(V) treatments. However, the application of glycine significantly enhanced the translocation of Fe and Na in the shoot. Besides, the expression of lower silicon transporters i.e. Lsi-1 and Lsi-2 was observed to be significantly suppressed in the root with the application of glycine against As treatment. Similarly, the expression of three GRX and two GST gene isoforms were found to be significantly increased with glycine application. Simultaneously, the activities of antioxidant enzymes i.e. l-arginine dependent NOS, SOD, NTR and GRX were found to be significantly enhanced in the presence of glycine. Increased activities of antioxidant enzymes coincided with the decreased level of TBARS and H2O2 in rice seedlings. Overall, the results suggested that the application of glycine reduces As accumulation through suppressing the gene expression of lower silicon transporters and ameliorates As toxicity by enhancing antioxidants defense mechanism in rice seedlings.

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[This corrects the article on p. 740 in vol. 7, PMID: 27313586.].

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GABA counteracts wide range of stresses through regulation of GABA shunt pathway in plants. Although, GABA assisted tolerance against As toxicity in plants is still unexplored. We have examined GABA induced tolerance in rice seedlings with two exposure periods of GABA i.e., short term and long term. Results showed that accumulation of GABA reduced the expressions of Lsi-1 and Lsi-2 transporter genes, which ultimately decreased the accumulation of As in rice seedlings. The accumulation of GABA also modulated the gene expression of GABA shunt pathway and activity of antioxidant enzymes, which strongly induced the tolerance in plants. Antioxidant enzymes such as CAT, POD, GPX and SOD showed maximum alteration in activity with GABA accretion. In both exposure periods, long term accumulation of GABA was highly efficient to provide tolerance to plants against As(III), while higher level of GABA at short term was toxic. Tolerance responses of GABA towards As(III) was reflected by minimal changes in various physiological (WUE, A, gs, PhiPS2, qp, NPQ, ETR and Trmmol) and growth parameters with concomitant accumulation. Oxidative stress marker such as TBARS and H2O2 contents were reduced with GABA accumulation. These results suggested that GABA sturdily inhibits As accumulation and provides tolerance towards As(III).

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Arsenic (As) contamination of paddy rice is a serious threat all over the world particularly in South East Asia. Selenium (Se) plays important role in protection of plants against various abiotic stresses including heavy metals. Moreover, arsenite (AsIII) and selenite (SeIV) can be biologically antagonistic due to similar electronic configuration and sharing the common transporter for their uptake in plant. In the present study, the response of oxidative stress, phenolic compounds and nutrient elements was analyzed to investigate Se mediated As tolerance in rice seedlings during AsIII and SeIV exposure in hydroponics. Selenite (25µM) significantly decreased As accumulation in plant than As (25µM) alone treated plants. Level of oxidative stress related parameters viz., reactive oxygen species (ROS), lipid peroxidation, electrical conductivity, nitric oxide and pro-oxidant enzyme (NADPH oxidase), were in the order of As>As+Se>control>Se. Selenium ameliorated As phytotoxicity by increased level of phenolic compounds particularly gallic acid, protocatechuic acid, ferulic acid and rutin and thiol metabolism related enzymes viz., serine acetyl transferase (SAT) and cysteine synthase (CS). Selenium supplementation enhanced the uptake of nutrient elements viz., Fe, Mn, Co, Cu, Zn, Mo, and improved plant growth. The results concluded that Se addition in As contaminated environment might be an important strategy to reduce As uptake and associated phytotoxicity in rice plant by modulation of phenolic compounds and increased uptake of nutrient elements.

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[This corrects the article on p. 740 in vol. 7, PMID: 27313586.].

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Glutaredoxins (Grxs) are a family of small multifunctional proteins involved in various cellular functions, including redox regulation and protection under oxidative stress. Despite the high number of Grx genes in plant genomes (48 Grxs in rice), the biological functions and physiological roles of most of them remain unknown. Here, the functional characterization of the two arsenic-responsive rice Grx family proteins, OsGrx_C7 and OsGrx_C2.1 are reported. Over-expression of OsGrx_C7 and OsGrx_C2.1 in transgenic Arabidopsis thaliana conferred arsenic (As) tolerance as reflected by germination, root growth assay, and whole plant growth. Also, the transgenic expression of OsGrxs displayed significantly reduced As accumulation in A. thaliana seeds and shoot tissues compared to WT plants during both AsIII and AsV stress. Thus, OsGrx_C7 and OsGrx_C2.1 seem to be an important determinant of As-stress response in plants. OsGrx_C7 and OsGrx_C2.1 transgenic showed to maintain intracellular GSH pool and involved in lowering AsIII accumulation either by extrusion or reducing uptake by altering the transcript of A. thaliana AtNIPs. Overall, OsGrx_C7 and OsGrx_C2.1 may represent a Grx family protein involved in As stress response and may allow a better understanding of the As induced stress pathways and the design of strategies for the improvement of stress tolerance as well as decreased As content in crops.

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Arsenic (As) is an acute poison and class I carcinogen, can cause a serious health risk. Staple crops like rice are the primary source of As contamination in human food. Rice grown on As contaminated areas accumulates higher As in their edible parts. Based on our previous transcriptome data, two rice glutaredoxins (OsGrx_C7 and OsGrx_C2.1) were identified that showed up-regulated expression during As stress. Here, we report OsGrx_C7 and OsGrx_C2.1 from rice involved in the regulation of intracellular arsenite (AsIII). To elucidate the mechanism of OsGrx mediated As tolerance, both OsGrxs were cloned and expressed in Escherichia coli (Δars) and Saccharomyces cerevisiae mutant strains (Δycf1, Δacr3). The expression of OsGrxs increased As tolerance in E. coli (Δars) mutant strain (up to 4 mM AsV and up to 0.6 mM AsIII). During AsIII exposure, S. cerevisiae (Δacr3) harboring OsGrx_C7 and OsGrx_C2.1 have lower intracellular AsIII accumulation (up to 30.43% and 24.90%, respectively), compared to vector control. Arsenic accumulation in As-sensitive S. cerevisiae mutant (Δycf1) also reduced significantly on exposure to inorganic As. The expression of OsGrxs in yeast maintained intracellular GSH pool and increased extracellular GSH concentration. Purified OsGrxs displays in vitro GSH-disulfide oxidoreductase, glutathione reductase and arsenate reductase activities. Also, both OsGrxs are involved in AsIII extrusion by altering the Fps1 transcripts in yeast and protect the cell by maintaining cellular GSH pool. Thus, our results strongly suggest that OsGrxs play a crucial role in the maintenance of the intracellular GSH pool and redox status of the cell during both AsV and AsIII stress and might be involved in regulating intracellular AsIII levels by modulation of aquaporin expression and functions.

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The present study evaluates the reduction of arsenate (As[V]) uptake in rice seedlings through individual and combined supplementation of phosphate (PO4(3-)) and selenite (Se[IV]) in a hydroponic condition. The toxic response in seedlings receiving As(V) manifested as inhibition in physiological parameters such as water use efficiency, stomatal conductance, photosynthetic assimilation rate, transpiration rate, photochemical quenching, and electron transport rate, along with growth. Arsenic accumulation significantly decreased with Se(IV) treatment (0.5 µg mL(-1), 1 µg mL(-1), and 2 µg mL(-1)) in a dose-dependent manner (20%, 35%, and 53%, respectively); however, it compromised the PO4(3-) level and physiological performance. The lower level of Se(IV), (0.5 µg mL(-1)), was relatively beneficial in terms of reduction in As accumulation than the higher level of Se(IV), (2 µg mL(-1)), which was rather toxic. Further, decrease in As uptake, replenished the level of PO4(3-) and physiological performance in seedlings treated with As+Se+P compared with those treated with As+Se. However, supplementation with only PO4(3-) (10 µg mL(-1) and 20 µg mL(-1)) along with As(V) was less effective in reducing As accumulation compared with As+Se. Seedlings receiving As+Se+P also exhibited lower thiobarbituric acid-reactive substances (TBARS) and electrical conductivity levels compared with both As+Se and As+P. Among all the treatments, the activity of antioxidant enzymes was highest in plants treated with As+Se+P. Hence, the higher antioxidant enzyme activity in As+Se+P along with lower levels of TBARS, H2 O2 , and As accumulation are attributed to the competitive reduction in As uptake in the presence of Se(IV) and PO4(3-).

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