Chelate Reductase Activity Research Articles

Biochar-based nanoparticles mitigated arsenic toxicity and improved physiological performance of basil via enhancing cation exchange capacity and ferric chelate reductase activity

The modified biochars have positive effects in reducing heavy metal toxicity for plants. However, the mechanism and extent of these effects on mitigating arsenic toxicity and plant performance are not clear. Thus, a pot experiment was conducted as factorial to evaluate the potential of fresh and enriched biochars with potassium and magnesium nano-sulfates [potassium-enriched biochar (K-BC), magnesium-enriched biochar (Mg-BC) in individual and combined forms] on reducing arsenic toxicity (non-contamination, 50, and 100 mg NaAsO2 kg−1 soil) in basil plants. Biochar-related treatments reduced plant arsenic absorption rate (up to 24%), arsenic content of root (up to 38%) and shoot (up to 21%) and root tonoplast H+-ATPase activity (up to 30%). The fresh and particularly enriched biochars improved soil properties (pH, CEC, and available iron content), ferric chelate reductase activity, iron, potassium and magnesium contents of plant tissues, chlorophyll content index, photochemical efficiency of photosystem II, relative electron transport rate, leaf area, and basil growth (shoot and root dry weight). These results revealed that enriched biochars are useful soil amendments for improving physiological performance of plants via reducing heavy metal toxicity and enhancing cation exchange capacity, nutrient availability and ferric chelate reductase activity. Therefore, soil amendment by enriched biochars could be a sustainable solution for enhancing plant productivity in contaminated soils via mitigating environmental impacts. This is an environmentally friendly method for using the natural wastes to overcome the adverse effects of soil pollutants on medicinal plants.

Brief characterisation of Fe chlorosis in chia (Salvia hispanica L.) plants grown in nutrient solution

ABSTRACT Chia (Salvia hispanica L.) plant is a well-known plant due to the nutraceutical value of its seeds. The aim of this preliminary study was to assess the response of Chia plants to Fe deficiency. Chia plants were grown for 12 days in Hoagland’s nutrient solutions without Fe (Fe0) and with Fe (Fe10-10 µM Fe). Biomass parameters and root ferric chelate-reductase activity (FC-R; EC 1.16.1.17) were determined at the end of the experiment. Chlorophyll estimations (expressed as SPAD readings) decreased progressively, showing the typical symptoms of iron chlorosis. In addition, iron-deficient chia plants exhibit smaller biomass (number of leaves, root, and shoot growth reduction) compared to control plants. These plants also showed morphological changes in roots. Furthermore, root FC-R activity was significantly lower in Fe0 plants.

Coated Hematite Nanoparticles Alleviate Iron Deficiency in Cucumber in Acidic Nutrient Solution and as Foliar Spray.

Micronutrient iron (Fe) deficiency poses a widespread agricultural challenge with global implications. Fe deficiency affects plant growth and immune function, leading to reduced yields and contributing to the global "hidden hunger." While conventional Fe-based fertilizers are available, their efficacy is limited under certain conditions. Most recently, nanofertilizers have been shown as promising alternatives to conventional fertilizers. In this study, three nanohematite/nanoferrihydrite preparations (NHs) with different coatings were applied through the roots and shoots to Fe-deficient cucumber plants. To enhance Fe mobilization to leaves during foliar treatment, the plants were pre-treated with various acids (citric acid, ascorbic acid, and glycine) at a concentration of 0.5 mM. Multiple physiological parameters were examined, revealing that both root and foliar treatments resulted in improved chlorophyll content, biomass, photosynthetic parameters, and reduced ferric chelate reductase activity. The plants also significantly accumulated Fe in their developing leaves and its distribution after NHs treatment, detected by X-ray fluorescence mapping, implied long-distance mobilization in their veins. These findings suggest that the applied NHs effectively mitigated Fe deficiency in cucumber plants through both modes of application, highlighting their potential as nanofertilizers on a larger scale.

Enhanced Germination and Growth of Alfalfa with Seed Presoaking and Hydroponic Culture in Fe2O3 Magnetic Nanoparticles

Nanofertilizers can be used as potential contenders to provide macro- and micronutrients to plants. Specifically, iron-oxide-based engineered nanoparticles are promising candidates for next-generation iron-deficiency fertilizers. Aiming to investigate the effect of Fe2O3 magnetic nanoparticles on plant germination and growth, alfalfa seeds were presoaked by a series of concentrations (0, 50, 100, 150, and 200 mg/L) of Fe2O3 NPs in this study. The germination rate, root length, chlorophyll content, and activity of the antioxidant enzymes (superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT)) were detected. Further, hydroponic alfalfa young seedlings were treated with 50 mg/L Fe2O3 NPs, with 50 mg/L Fe-EDTA as the control. The growth index, chlorophyll content, metal (Fe, Cu, Zn, and Mn) content, and ferric-chelate reductase activity were detected. The results indicated that the presoaking of Fe2O3 NPs promoted alfalfa seed germination in all treatments. Short-time of Fe2O3 NPs presoaking has not affected chlorophyll and iron content while increasing antioxidase (SOD, POD, and CAT) activities at 50 and 200 mg/L concentrations. Fe2O3 NPs of 50 mg/L have the most beneficiary impact on alfalfa seed germination by presoaking. Fe2O3 NPs of 50 mg/L enhanced the seedlings’ growth and increased chlorophyll content, Fe content, and Mn content of hydroponic alfalfa compared with the control. Moreover, ferric chelate reductase activity was significantly lower in alfalfa roots exposure to Fe2O3 NPs than in the control. The results showed that 50 mg/L Fe2O3 NPs could be used as an appropriate and effective treatment concentration for seed pretreatment and fertilizer application. The growth-promoting effect of Fe2O3 NPs on alfalfa is related to its nanostructured properties. More in-depth research is still needed to understand the growth-promoting mechanism of Fe2O3 NPs and the impact of Fe2O3 NPs on the field environment.

The low ferric chelate reductase activity and high apoplastic pH in leaves cause iron deficiency chlorosis in ‘Huangguan’ pears grafted onto quince A grown in calcareous soil

Quince (Cydonia oblonga Mill.) is a dwarfing rootstock often used in pear cultivation. However, the pear cultivar ‘Huangguan’ (Pyrus bretschneideri Rehd. cv) grafted onto quince A (HG-QA) suffered iron (Fe) deficiency chlorosis in the calcareous soils of North China, while ‘Huangguan’ grafted onto Pyrus betulifolia (HG-PB) did not. We hypothesized that the higher leaf apoplastic pH of HG-QA than HG-PB causes Fe deficiency chlorosis by restricting Fe transportation within leaves. Three-year-old rootstocks quince A and Pyrus betulifolia and the combinations HG-QA and HG-PB were grown in the same orchard in a calcareous soil. Newly expanded leaves were analysed for Fe related properties. Micro X-ray fluorescence analysis was used for Fe mapping within the individual leaves. The extractable Fe(II) concentrations in quince A and HG-QA leaves were much lower than those in Pyrus betulifolia and HG-PB, even though the total leaf Fe concentrations were similar. More Fe was located near the leaf midrib in quince A and HG-QA than in Pyrus betulifolia and HG-PB. These were correlated with the lower ferric chelate reductase (FCR) activity in the chlorotic leaves of the quince A rootstock than Pyrus betulifolia and the lower FCR activity and higher apoplastic pH in the chlorotic leaves of the HG-QA rootstock-scion combination than HG-PB. In conclusion, the reduced Fe availability within the leaves caused by the lower FCR activity and higher apoplastic pH compared with those of HG-PB led to HG-QA leaf chlorosis in calcareous soils. This result implies that rootstocks are involved in the regulation of leaf Fe utilization by scions.

Apoplast utilisation of nanohaematite initiates parallel suppression of RIBA1 and FRO1&3 in Cucumis sativus

Nanoscale Fe containing particles can penetrate the root apoplast. Nevertheless, cell wall size exclusion questions that for Fe mobilisation, a close contact between the membrane integrating FERRIC REDUCTASE OXIDASE (FRO) enzymes and Fe containing particles is required. Haematite nanoparticle suspension, size of 10–20 nm, characterized by 57Fe Mössbauer spectroscopy, TEM, ICP and SAED was subjected to Fe utilisation by the flavin secreting model plant cucumber (Cucumis sativus). Alterations in the structure and distribution of the particles were revealed by 57Fe Mössbauer spectroscopy, HRTEM and EDS element mapping. Biological utilisation of Fe resulted in a suppression of Fe deficiency responses (expression of CsFRO 1, 2 &3 and RIBOFLAVIN A1; CsRIBA1 genes and root ferric chelate reductase activity). Haematite nanoparticles were stacked in the middle lamella of the apoplast. Fe mobilisation is evidenced by the reduction in the particle size. Fe release from nanoparticles does not require a contact with the plasma membrane. Parallel suppression in the CsFRO 1&3 and CsRIBA1 transcript amounts support that flavin biosynthesis is an inclusive Fe deficiency response involved in the reduction-based Fe utilisation of Cucumis sativus roots. CsFRO2 is suggested to play a role in the intracellular Fe homeostasis.

Effects of foliar application of organic acids on strawberry plants

The large economic costs and environmental impacts of iron-chelate treatments has led to the search for alternative methods and compounds to control iron (Fe) deficiency chlorosis. Strawberry plants (Fragaria x ananassa) were grown in Hoagland's nutrient solution in a greenhouse with two levels of Fe: 0 and 10 μM Fe(III)-EDDHA. After 20 days, plants growing without Fe showed typical symptoms of Fe deficiency chlorosis in young leaves. Then, the adaxial and abaxial sides of one mature or one young leaf in each plant were brushed with 10 mM malic (MA), citric (CA) or succinic (SA) acids. Eight applications were done over a two-week period. At the end of the experiment, the newly emerged (therefore untreated), young and mature leaves were sampled for nutritional and metabolomic analysis, to assess the effectiveness of treatments. Leaf regreening was monitored using a SPAD-502 apparatus, and the activity of the ferric chelate-reductase activity (FCR) was measured using root tips. Iron deficiency negatively affected biomass and leaf chlorophyll but did not increase FCR activity. Application of succinic acid alleviated the decrease in chlorophyll observed in other treatments, and the overall nutritional balance in the plant was also changed. The concentrations of two quinic acid derivatives increased under Fe deficiency and decreased in plants treated with succinic acid, and thus they are proposed as Fe stress markers. Data suggest that foliage treatments with carboxylates may be, in some cases, environmentally friendly alternatives to Fe(III)-chelates. The importance of Fe mobilization pathways in the formulation of new fertilizers is also discussed.

Growth and physiological impairments in Fe-starved alfalfa are associated with the downregulation of Fe and S transporters along with redox imbalance

BackgroundIron (Fe) is an essential plant nutrient. Its deficiency is a major constraint in crop production systems, affecting crop yield and quality. It is therefore important to elucidate the responses and adaptive mechanisms underlying Fe-deficiency symptoms in alfalfa.Materials and methodsThe experiment was carried out on 12-day-old alfalfa plants grown in hydroponics under Fe-sufficient and Fe-deficient conditions.ResultsThe Fe-starved alfalfa showed decreased plant biomass, chlorophyll score, PSII efficiency, and photosynthesis performance index in young leaves under low Fe. Further, Fe shortage reduced the Fe, Zn, S and Ca concentration in root and shoot of alfalfa accompanied by the marked decrease of MsIRT1, MsZIP, MsSULTR1;1, MsSULTR1;2 and MsSULTR1;3 transcripts in root and shoot. It indicates that retardation caused by Fe-deficiency was also associated with the status of other elements, especially the reduced Fe and S may be coordinately attributed to the photosynthetic damages in Fe-deficient alfalfa. The ferric chelate reductase activity accompanied by the expression of MsFRO1 in roots showed no substantial changes, indicating the possible involvement of this Strategy I response in Fe-deficient alfalfa. However, the proton extrusion and expression of MsHAI1 were significantly induced following Fe-deficiency. In silico analysis further suggested their subcellular localization in the plasma membrane. Also, the interactome map suggested the partnership of MsFRO1 with plasma membrane H+-ATPase, transcription factor bHLH47, and nitrate reductase genes, while MsHAI1 partners include ferric reductase-like transmembrane component, plasma membrane ATPase, vacuolar-type H-pyrophosphatase, and general regulatory factor 2. In this study, SOD and APX enzymes showed a substantial increase in roots but unable to restore the oxidative damages in Fe-starved alfalfa.ConclusionThese findings promote further studies for the improvement of Fe-starved alfalfa or legumes through breeding or transgenic approaches.Graphic

Differential response of pea (Pisum sativum L.) genotypes to iron deficiency in relation to the growth, rhizosphere acidification and ferric chelate reductase activities

Calcareous soils are known problematic lands for agricultural systems because of the low availability of nutrients, particularly iron (Fe). The so-called strategy I plant (e. g. Pea, Pisum sativum L.) which groups dicotyledons and monocots other than grasses, developed root membrane activities that contribute to the improvement of Fe availability. Among the functions considered to be a critical phase in iron absorption is rhizosphere acidification by H-ATPase and Fe(III) reduced by Fe(III) chelate reducctase (FeCR). In order to experimentally investigate the importance of root FeCR in Fe nutrition, its relationship with rhizosphere acidification and the genotypic differences in response to iron deficiency in pea (Pisum sativum L.), a glasshouse experiment was conducted hydroponically on four genotypes Merveille de Kelvedon (MK); Lincoln (Lin); Douce de Provence (DP) and Alexandra (Alex). Plants of each genotype were distributed into two plots, the first one received full nutrient solution (+ Fe), the second one received nutrient solution devoid of iron (- Fe). Plant growth, Fe distribution, SPAD index and root acidification and ferric chelate reductase activities were evaluated. Fe deficiency decreased plant growth and SPAD index along with the significant increase of H-ATPase and FeCR activities. Some genotypic differences were observed as follows; Alex showed high tolerance to Fe deprivation as compared to other genotypes. Important H-ATPase and FeCR activities, high Fe use efficiency and adequate membrane efficiency are the main reasons for this tolerance. These physiological parameters could be used as tools of tolerance for further breeding programs

Silicon induces metallochaperone-driven cadmium binding to the cell wall and restores redox status through elevated glutathione in Cd-stressed sugar beet.

Cadmium (Cd) is toxic; however, whether silicon (Si) alleviates Cd toxicity was never studied in sugar beet. The study was conducted on 2-week-old sugar beet cultivated in the presence or absence of Cd (10μM CdSO4 ) and Si (1 mM Na2 SiO3 ) in hydroponic conditions. The morphological impairment and cellular damages observed in sugar beet upon Cd toxicity were entirely reversed due to Si. Si substantially restored the energy-providing ability, absorbed energy flux, and electron transport toward PSII, which might be correlated with the upregulation of BvIRT1 and ferric chelate reductase activity leading to the restoration of Fe status in Cd-stressed sugar beet. Although Si caused a reduction of shoot Cd, the root Cd substantially increased under Cd stress, a significant part of which was retained in the cell wall rather than in the root vacuole. While the concentration of phytochelatin and the expression of BvPCS3 (PHYTOCHELATIN SYNTHASE 3) showed no changes upon Si exposure, Si induced the expression of BvHIPP32 (HEAVY METAL-ASSOCIATED ISOPRENYLATED PLANT PROTEIN 32) in the Cd-exposed root. The BvHIPP32 and AtHIPP32 metallochaperone proteins are localized in the cell wall and they share similar sequence alignment, physiochemical properties, secondary structure, cellular localization, motif locations, domain association, and metal-binding site (cd00371) linked to the metallochaperone-like protein. It suggests that Si reduces the Cd level in shoot by retaining the excess Cd in the cell wall of roots due to the induction of BvHIPP32 gene. Also, Si stimulates glutathione-related antioxidants along with the BvGST23 expression, inferring an ascorbate-glutathione ROS detoxification pathway in Cd-exposed plants.

Application of Novel Microorganism-Based Formulations as Alternative to the Use of Iron Chelates in Strawberry Cultivation

The strawberry is a low-growing, herbaceous perennial plant, sensitive to iron deficiency. The iron deficiency represents a nutritional disorder, leading to a decreased content of photosynthetic pigments, which determines the yellow color characteristic of chlorotic leaves. Therefore, in calcareous soils, the use of synthetic iron chelate is often mandatory in strawberry cultivation. The employment of novel microorganism-based formulations as alternatives to the use of iron chelates, was evaluated during strawberry cultivation by monitoring the morpho-biometric parameters, chlorophylls, the iron content in leaves and roots, and the Fe chelate reductase activity involved in absorption of iron during the chlorosis event in plants using the strategy I. The experimental design envisaged growing strawberry seedlings on an inert substrate (pumice), irrigated with Hoagland solution iron-free, with a 12 h photoperiod. After 42 days, at the first appearance of chlorosis symptoms, plants were transplanted into a calcareous soil, and after seven days, they were treated, by a single application, with a microorganism-based formulations (MBF), an inoculum (In) of Trichoderma spp. and Streptomyces spp., or Sequestrene (Sq). Strawberry plants were sampled and analyzed at 5, 10, 15, and 20 days from the treatments. The results showed that microorganism-based formulations positively affected the strawberry seedlings, by reducing the chlorosis symptoms, producing comparable effects to the Sequestrene treatment.

Adaptive strategies to minimise iron limiting stress under climate change scenario: A study pertinent to iron stress response of two soybean (Glycine max (L.) Merr.) Genotypes

The response of soybean genotypes to iron deficiency stress under elevated CO2 and temperature condition could be guided by three critical rhizospheric processes viz. proton (H+) extrusion, root exudation and ferric chelate reductase (FCR) activity. In the present study, the iron efficient and responsive (FeER) genotype recorded an impressive performance over iron inefficient and responsive (FeIR) genotype in counteracting iron deficiency stress but experienced modest stress caused by the combined interaction between the genotype (G), environment (E) and HCO3- ion (B). The antagonistic interaction between Fe2+ with HCO3- ion resulted in greater iron stress. Plants grown in the absence of bicarbonate have significantly higher total chlorophyll content (1.79±0.04 mg g-1, mean ± SE) than plants grown in presence of bicarbonate (1.48 ± 0.06 mg g-1). To warfare the constraints in Fe availability, especially under more stressed e-[CO2+T] environmental condition in the presence of bicarbonate ion, the root system of iron efficient genotype of soybean (FeER) exuded out significantly higher amount of low molecular weight organic acids. Furthermore, the presence of bicarbonate ion in the nutrient solution exacerbated the iron deficiency stress and consequently resulted in higher proton extrusion (~1.2 fold increase), lower ferric chelate reductase activity (~1.3 fold decrease) and higher organic acid exudation (up to ~1.9 fold increase in malic acid). The intra-specific variability between contrasting genotypes and their response to elevated CO2 and temperature could be exploited to remediate emerging Fe deficiency of soybean plants under climate change scenario.

Streptomyces hygroscopicus OsiSh-2-induced mitigation of Fe deficiency in rice plants

The limited availability of nutrient Fe severely impairs the health of almost all organisms. Endophytic actinobacteria can benefit the host plant in different ways. We previously inferred that the rice (Oryza) endophytic Streptomyces hygroscopicus OsiSh-2 possesses a highly efficient Fe-acquisition system. In this work, we first evaluated the effects of OsiSh-2 on the Fe-deficiency resilience of the host rice. The results demonstrated that the inoculation of OsiSh-2 considerably increased the plant biomass, Fe concentration and translocation factor, and chlorophyll content, and net leaf photosynthetic rate under Fe limiting condition. The expression of genes involved with Fe3+-reduction-related strategy in rice was up-regulated, while that involved with Fe3+-chelation-related strategy was down-regulated by OsiSh-2 treatment. Meanwhile, the OsiSh-2-rice symbiont showed enhancement of Fe3+-chelate reductase activity, total siderophore production, and acidification trend in the rhizosphere under Fe deficiency compared to plants without this endophyte. In conclusion, endophytic OsiSh-2 could protect plants against Fe-deficient stress by a sophisticated interaction with the host, including modulating Fe chelation, solubilization, reduction and translocation, ultimately leading to enhanced fitness of plant.

Changes in physiological activities and root exudation profile of two grapevine rootstocks reveal common and specific strategies for Fe acquisition

In several cultivation areas, grapevine can suffer from Fe chlorosis due to the calcareous and alkaline nature of soils. This plant species has been described to cope with Fe deficiency by activating Strategy I mechanisms, hence increasing root H+ extrusion and ferric-chelate reductase activity. The degree of tolerance exhibited by the rootstocks has been reported to depend on both reactions, but to date, little emphasis has been given to the role played by root exudate extrusion. We studied the behaviour of two hydroponically-grown, tolerant grapevine rootstocks (Ramsey and 140R) in response to Fe deficiency. Under these experimental conditions, the two varieties displayed differences in their ability to modulate morpho-physiological parameters, root acidification and ferric chelate reductase activity. The metabolic profiling of root exudates revealed common strategies for Fe acquisition, including ones targeted at reducing microbial competition for this micronutrient by limiting the exudation of amino acids and sugars and increasing instead that of Fe(III)-reducing compounds. Other modifications in exudate composition hint that the two rootstocks cope with Fe shortage via specific adjustments of their exudation patterns. Furthermore, the presence of 3-hydroxymugenic acid in these compounds suggests that the responses of grapevine to Fe availability are rather diverse and much more complex than those usually described for Strategy I plants.

Arbuscular Mycorrhizal Symbiosis Mitigates Iron (Fe)-Deficiency Retardation in Alfalfa (Medicago sativa L.) Through the Enhancement of Fe Accumulation and Sulfur-Assisted Antioxidant Defense.

Iron (Fe)-deficiency is one of the major constraints affecting growth, yield and nutritional quality in plants. This study was performed to elucidate how arbuscular mycorrhizal fungi (AMF) alleviate Fe-deficiency retardation in alfalfa (Medicago sativa L.). AMF supplementation improved plant biomass, chlorophyll score, Fv/Fm (quantum efficiency of photosystem II), and Pi_ABS (photosynthesis performance index), and reduced cell death, electrolyte leakage, and hydrogen peroxide accumulation in alfalfa. Moreover, AMF enhanced ferric chelate reductase activity as well as Fe, Zn, S and P in alfalfa under Fe-deficiency. Although Fe-transporters (MsIRT1 and MsNramp1) did not induce in root but MsFRO1 significantly induced by AMF under Fe deficiency in roots, suggesting that AMF-mediated Fe enhancement is related to the bioavailability of Fe at rhizosphere/root apoplast rather than the upregulation of Fe transporters under Fe deficiency in alfalfa. Several S-transporters (MsSULTR1;1, MsSULTR1;2, MsSULTR1;3, and MsSULTR3;1) markedly increased following AMF supplementation with or without Fe-deficiency alfalfa. Our study further suggests that Fe uptake system is independently influenced by AMF regardless of the S status in alfalfa. However, the increase of S in alfalfa is correlated with the elevation of GR and S-metabolites (glutathione and cysteine) associated with antioxidant defense under Fe deficiency.

Effects of Rahnella aquatilis JZ-GX1 on Treat Chlorosis Induced by Iron Deficiency in Cinnamomum camphora

With the increasing popularity of urban landscaping, there is a greater need to address iron deficiency and chlorosis in Cinnamomum camphora. Beneficial microorganisms can play an important role in improving plant iron nutrition. In this study, we evaluated the greening effect that results from inoculating C. camphora with Rahnella aquatilis JZ-GX1. We conducted in vitro experiments to determine the effectiveness of JZ-GX1 in reducing extracellular iron(III) ions in siderophores and producing organic acids under low-iron conditions. Potted, chlorotic C. camphora seedlings were inoculated, and parameters related to growth and iron nutritional status were measured. Inoculation by JZ-GX1 had a more pronounced greening effect on C. camphora than the traditional iron sulfate treatment for plant iron deficiency. Inoculated plants exhibited higher levels of active iron in the leaves, enhanced rhizosphere acidification capacity and ferric chelate reductase activity. Furthermore, the complete root system and chloroplast developmental structures were observed. Our results demonstrate the potential roles of R. aquatilis JZ-GX1 in promoting iron absorption in C. camphora.

Effects of exogenous SA supplied with different approaches on growth, chlorophyll content and antioxidant enzymes of peanut growing on calcareous soil

To assess the role of salicylic acid (SA) supplied with 5 approaches in alleviating chlorosis induced by iron (Fe) deficiency in peanut plants growing on calcareous soil, SA was supplied as soil incorporation, making slow-release particles, seed soaking, irrigation and foliar application. SA application, particularly, SA supplied by slow release particles, dramatically increased growth parameters, yield and quality of peanut, and increased Fe concentration in peanut grain. Meanwhile, SA application increased the H+-ATPase activity, reduced pH of soil, increased Fe3+-Chelate Reductase (FCR) activity in roots, and increased Fe concentration in roots. Furthermore, SA increased active Fe content and increased chlorophyll content. In addition, SA improved enzymes activities containing superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), and protected Fe deficiency induced oxidative stress. Therefore, SA has a good effect on alleviating chlorosis induced by Fe deficiency on calcareous soil. However, in the 5 SA supplied approaches, foliar application and making slow release particles were more effective.

Iron (III) oxide nanoparticles alleviate arsenic induced stunting in Vigna radiata

Iron nanoparticles (NPs) are widely used for the removal of arsenic from water. In this study, we evaluated the interaction between arsenate (AsO43−) and Fe2O3-NPs on early seedling growth of Vigna radiata. Seedlings were raised in AsO43− and Fe2O3-NPs, alone and in combination. While Fe2O3-NPs slightly promoted seedling growth, AsO43− reduced seedling growth drastically. AsO43--induced decline in the seedling growth was recovered by Fe2O3-NPs. In contrast, equivalent concentrations of FeCl3, alone and together with AsO43−, inhibited seed germination completely. Lower arsenic content in seedlings raised in the presence of Fe2O3-NPs indicated that Fe2O3-NPs restricted arsenic uptake. Ability of Fe2O3-NPs to restrict the arsenic uptake of the seedlings was due to adsorption of AsO43−, as revealed by transmission and scanning electron microscopy. Non-toxic levels of iron in seedlings were due to restriction of Fe2O3-NPs to root-surface. AsO43− enhanced the ferric chelate reductase activity of root which was recovered by Fe2O3-NPs. The AsO43--induced oxidative stress, evident from high levels of proline, H2O2 and malondialdehyde, and lowered root oxidisability was ameliorated by Fe2O3-NPs. AsO43-induced enhancement in total antioxidant capacity, superoxide dismutase and catalase activity, and decline in guaiacol peroxidase activity were antagonized by Fe2O3-NPs. Our findings reveal that Fe2O3-NPs provide effective resistance/amelioration to arsenic toxicity by reducing arsenic availability to plants.

Nano-hives for plant stimuli controlled targeted iron fertilizer application

In spite of iron being an abundant element present in soil, often crops show iron deficiency, because it is not present in phyto-available forms. External application is also not successful, because of soil carbonate/bicarbonate ions assisted conversion into unavailable oxy hydroxyl forms. Here the chitosan coating on iron powder loaded mesoporous silica have been found to control the above undesired soil reaction. The coating acts as gate, which close the pores in the presence of carbonate ions to keeps the iron in phyto-available forms, whereas open the pores in the presence of the uptake proton signal from the roots. This phenomenon of excellent control in the nutrient supply to plant is a complementary effect of the pH responsive chitosan and the mesoporous channel. Because in the absence of either of the component, the performance is reduced. In the tomato plant experiment, the ferric chelate reductase activity, an iron deficiency parameter, is reduced by ~20% in plants treated with FeSO4@MS@CH compared to the one treated with FeSO4@MS.

Cadmium tolerance is associated with the root-driven coordination of cadmium sequestration, iron regulation, and ROS scavenging in rice

Excess cadmium (Cd) is a serious threat to agriculture and the environment. High Cd availability showed no significant decline in growth, chlorophyll synthesis, soluble protein, cell and membrane stability in Sonarbangla (Cd-tolerant), while these were severely affected in BRRI 72 (Cd-sensitive). Atomic absorption spectroscopy analysis demonstrated a huge increment of Cd and Fe in root and shoot of BRRI 72; however, Sonarbangla only exhibited a significant increase of Cd in roots. It suggests that excess Cd in Sonarbangla possibly retained in roots through vacuolar sequestration without interfering cell functions. This was further confirmed by the increased accumulation of cysteine, glutathione, and phytochelatin along with OsPCS1 and OsHMA3 upregulation, possibly facilitated by nitric oxide in roots of Sonarbangla. Further, Fe chelate reductase activity in conjunction with the genes (OsFRO1, OsNRAMP1, OsIRT1, and OsYSL15) associated with Fe availability significantly upregulated in BRRI 72 but not in Sonarbangla in response to Cd. It advises that Fe acquisition and transport were tightly regulated in Cd-tolerant Sonarbangla. Furthermore, elevated CAT, APX, GR, NO in root along with shoot sugar helps rice plants to withstand Cd-induced oxidative damage. Finally, reciprocal grafting combining Sonarbangla rootstock with either BRRI 72 or Sonarbangla scion showed Sonarbangla type tolerance along with no changes of H2O2 and Fe reductase activity in roots under high Cd. It indicates that the signal inducing the responses to adjust Cd stress is originated in the root system. These messages deliver essential background for further breeding program to produce Cd-free rice.