Arsenic (As) contamination in rice is at alarming level as majority of rice growing regions are As contaminated such as South East Asia. Restricting the As in aerial parts of rice plant may be an ...effective strategy to reduce As contamination in food chain. Sulfur (S), an essential element for plant growth and development, plays a crucial role in diminishing heavy metal toxicity. Current study is designed to investigate the role of S to mitigate As toxicity in rice under different S regimes. High S (5 mM) treatment resulted in enhanced root As accumulation as well as prevented its entry in to shoot. Results of thiol metabolism indicate that As was complexed in plant roots through enhanced synthesis of phytochelatins. High S treatment also reduced the expression of OsLsi1 and OsLsi2, the potent transporters of As in rice. High S treatment enhanced the activities of antioxidant enzymes and mitigated the As induced oxidative stress. Thus from present study it is evident that proper supply of S nutrition may be helpful in prevention of As accumulation in aerial parts of plant as well as As induced toxicity.
•Different S concentrations were applied to study As detoxification mechanism.•Thiols and enzymes of S assimilatory pathway play vital role in As detoxification.•Enhanced S supply immobilized the As in roots and lower its translocation to shoot.•Arsenite and sulfate transporters are governed by S concentrations.
•Arsenic detoxification was mediated by PCs, NPTs and enzymes of S assimilatory pathway.•Sulfur supply results in immobilization of As in rice roots and low translocation to shoot.•Sulfur nutrition ...regulates arsenite and sulfate transporters in rice root.•High S ameliorates As toxicity by enhancing antioxidant enzymes activity.
Arsenic (As) contamination is a global issue, with South Asia and South East Asia being worst affected. Rice is major crop in these regions and can potentially pose serious health risks due to its known As accumulation potential. Sulfur (S) is an essential macronutrient and a vital element to combat As toxicity. The aim of this study was to investigate the role of S with regards to As toxicity in rice under different S regimes. To achieve this aim, plants were stressed with AsIII and AsV under three different S conditions (low sulfur (0.5mM), normal sulfur (3.5mM) and high sulfur (5.0mM)). High S treatment resulted in increased root As accumulation, likely due to As complexation through enhanced synthesis of thiolic ligands, such as non-protein thiols and phytochelatins, which restricted As translocation to the shoots. Enzymes of S assimilatory pathways and downstream thiolic metabolites were up-regulated with increased S supplementation; however, to maintain optimum concentrations of S, transcript levels of sulfate transporters were down-regulated at high S concentration. Oxidative stress generated due to As was counterbalanced in the high S treatment by reducing hydrogen peroxide concentration and enhancing antioxidant enzyme activities. The high S concentration resulted in reduced transcript levels of Lsi2 (a known transporter of As). This reduction in Lsi2 expression level is a probable reason for low shoot As accumulation, which has potential implications in reducing the risk of As in the food chain.
Nanotechnology offers the potential to provide innovative solutions for sustainable crop production as plants are exposed to a combination of climate change factors (CO2, temperature, UV radiation, ...ozone), abiotic (heavy metals, salinity, drought), and biotic (virus, bacteria, fungi, nematode, and insects) stresses. The application of particular sizes, shapes, and concentration of nanomaterials (NMs) potentially mitigate the negative impacts in plants by modulation of photosynthetic rate, redox homeostasis, hormonal balance, and nutrient assimilation through upregulation of anti-stress metabolites, antioxidant defense pathways, and genes and genes network. The present review inculcates recent advances in uptake, translocation, and accumulation mechanisms of NMs in plants. The critical theme of this review provides detailed insights into different physiological, biochemical, molecular, and stress tolerance mechanism(s) of NMs action and their cross-talk with different phytohormones. The role of NMs as a double-edged sword for climate change factors, abiotic, and biotic stresses for nutrients uptake, hormones synthesis, cytotoxic, and genotoxic effects including chromosomal aberration, and micronuclei synthesis have been extensively studied. Importantly, this review aims to provide an in-depth understanding of the hormesis effect at low and toxicity at higher doses of NMs under different stressors to develop innovative approaches and design smart NMs for sustainable crop production.
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•Nanotechnology a solution for sustainable crop production.•Nanomaterials mitigate climate change factors, abiotic, and biotic stresses.•Crosstalk of nanomaterials and phytohormones.•Hormesis impacts of nanomaterials under different stressors.•Nanophytotoxicity, nanoplastic remediation.
Multidrug and Toxic compound Extrusion proteins (MATE) are a group of secondary active transporters with ubiquitous occurrences in all domains of life. This is a newly characterized transporter ...family with limited functional knowledge in plants. In this study, we functionally characterised two members of rice MATE gene family, OsMATE1 and OsMATE2 through expression in heterologous system, Arabidopsis. Expression of OsMATEs in Arabidopsis altered growth and morphology of transgenic plants. Genome-wide expression analysis revealed modulation of genes involved in plant growth, development and biotic stress in transgenic lines. Transgenic plants displayed sensitivity for biotic and abiotic stresses. Elevated pathogen susceptibility of transgenic lines was correlated with reduced expressions of defence related genes. Promoter and cellular localization studies suggest that both MATEs express in developing and reproductive organs and are plasma-membrane localised. Our results reveal that OsMATE1 and OsMATE2 regulate plant growth and development as well as negatively affect disease resistance.
Arsenic (As) is an emerging pollutant causing inhibition in growth and development of plants resulting into phytotoxicity. On the other hand, silicon (Si) has been suggested as a modulator in abiotic ...and biotic stresses that, enhances plant's physiological adaptations in response to several stresses including heavy metal stress. In this study, we used roots of hydroponically grown 14 day old seedlings of Brassica juncea var. Varuna treated with 150 μM As, 1.5 mM Si and both in combination for 96 h duration. Application of Si modulated the effect of As by improving morphological traits of root along with the development of both primary and lateral roots. Changes observed in root traits showed positive correlation with As induced cell death, accumulation of reactive oxygen species (ROS), nitric oxide (NO) and intracellular superoxide radicals (O2−). Addition of 1.5 mM Si during As stress increased accumulation of As in roots. Mineral nutrient analysis was done using energy-dispersive X-ray fluorescence (EDXRF) technique and positively correlated with increased cysteine, proline, MDA, H2O2 and activity of antioxidant enzymes (SOD, CAT and APX). The results obtained from the above biochemical approaches support the protective and active role of Si in the regulation of As stress through the changes in root developmental process.
•Silicon mitigates arsenic stress through the changes in root traits.•Si addition increased As uptake with simultaneous alleviation of As toxicity.•Histofluorescent staining showed decrease in As induced ROS damage by Si addition.•As + Si treatment improved root traits through decrease in MDA and H2O2 level.•Altered level of antioxidant enzymes and stress modulators were also observed.
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 AsIII stress mitigating effect of SeVI in rice. The level of As, thiolic ligands and AAs was analyzed in rice seedlings after exposure to AsIII/SeVI alone and AsIII+SeVI treatments. Selenate supplementation (AsIII 25μM+SeVI 25μM) decreased total As accumulation in both root and shoot (179 & 144%) as compared to AsIII alone treatment. The AsIII+SeVI treatment also induced the levels of non-protein thiols (NPTs), glutathione (GSH) and phytochelatins (PCs) as compared to AsIII alone treatment and also modulated the activity of enzymes of thiol metabolism. The content of amino acids (AAs) was significantly altered with SeVI supplementation. Importantly, essential amino acids (EAAs) were enhanced in AsIII+SeVI treatment as compared to AsIII alone treatment. In contrast, stress related non-essential amino acids (NEAAs) like GABA, Glu, Gly, Pro and Cys showed enhanced levels in AsIII alone treatment. In conclusion, rice supplemented with SeVI tolerated As toxicity with reduced As accumulation and increased the nutrition quality by increasing EAAs.
•Selenium supplementation reduced arsenic accumulation in rice.•Essential amino acids were enhanced in As+Se treatment.•As+Se treatment increased non-protein thiols and phytochelatins in rice.•Stress related nonessential amino acids were positively correlated to As accumulation.
Nitric oxide (NO) and salicylic acid (SA) are important signaling molecules in plant system. In the present study both NO and SA showed a protective role against arsenite (AsIII) stress in rice ...plants when supplied exogenously. The application of NO and SA alleviated the negative impact of AsIII on plant growth. Nitric oxide supplementation to AsIII treated plants greatly decreased arsenic (As) accumulation in the roots as well as shoots/roots translocation factor. Arsenite exposure in plants decreased the endogenous levels of NO and SA. Exogenous supplementation of SA not only enhanced endogenous level of SA but also the level of NO through enhanced nitrate reductase (NR) activity, whether AsIII was present or not. Exogenously supplied NO decreased the NR activity and level of endogenous NO. Arsenic accumulation was positively correlated with the expression level of OsLsi1, a transporter responsible for AsIII uptake. The endogenous level of NO and SA were positively correlated to each other either when AsIII was present or not. This close relationship indicates that NO and SA work in harmony to modulate the signaling response in AsIII stressed plants.
•Nitric oxide (NO) decreased the arsenic (As) accumulation in both root and shoot.•Salicylic acid (SA) decreased the root to shoot translocation of As.•NO and SA mitigated the As-mediated oxidative stress.•NO and SA were worked in a mutually coordination manner irrespective of As presence.
Arsenic (As) contamination of rice is a major problem for South-East Asia. In the present study, the effect of selenium (Se) on rice (Oryza sativa L.) plants exposed to As was studied in hydroponic ...culture. Arsenic accumulation, plant growth, thiolic ligands and antioxidative enzyme activities were assayed after single (As and Se) and simultaneous supplementations (As + Se). The results indicated that the presence of Se (25 µM) decreased As accumulation by threefold in roots and twofold in shoots as compared to single As (25 µM) exposed plants. Arsenic induced oxidative stress in roots and shoots was significantly ameliorated by Se supplementation. The observed positive response was found associated with the increased activities of ascorbate peroxidase (APX; EC 1.11.1.11), catalase (CAT; EC 1.11.1.6) and glutathione peroxidase (GPx; EC 1.11.1.9) and induced levels of non-protein thiols (NPTs), glutathione (GSH) and phytochelatins (PCs) in As + Se exposed plants as compared to single As treatment. Selenium supplementation modulated the thiol metabolism enzymes viz., γ-glutamylcysteine synthetase (γ-ECS; EC 6.3.2.2), glutathione-S-transferase (GST; EC 2.5.1.18) and phytochelatin synthase (PCS; EC 2.3.2.15). Gene expression analysis of several metalloid responsive genes (LOX, SOD and MATE) showed upregulation during As stress, however, significant downregulation during As + Se exposure as compared to single As treatment. Gene expressions of enzymes of antioxidant and GSH and PC biosynthetic systems, such as APX, CAT, GPx, γ-ECS and PCS were found to be significantly positively correlated with their enzyme activities. The findings suggested that Se supplementation could be an effective strategy to reduce As accumulation and toxicity in rice plants.
Recent studies have identified rice (Oryza sativa) as a major dietary source of inorganic arsenic (As) and poses a significant human health risk. The predominant model for plant detoxification of ...heavy metals is complexation of heavy metals with phytochelatins (PCs), synthesized non-translationally by PC synthase (PCS) and compartmentalized in vacuoles. In this study, in order to restrict As in the rice roots as a detoxification mechanism, a transgenic approach has been followed through expression of phytochelatin synthase, CdPCS1, from Ceratophyllum demersum, an aquatic As-accumulator plant. CdPCS1 expressing rice transgenic lines showed marked increase in PCS activity and enhanced synthesis of PCs in comparison to non-transgenic plant. Transgenic lines showed enhanced accumulation of As in root and shoot. This enhanced metal accumulation potential of transgenic lines was positively correlated to the content of PCs, which also increased several-fold higher in transgenic lines. However, all the transgenic lines accumulated significantly lower As in grain and husk in comparison to non-transgenic plant. The higher level of PCs in transgenic plants relative to non-transgenic presumably allowed sequestering and detoxification of higher amounts of As in roots and shoots, thereby restricting its accumulation in grain.
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