The effect of combining green iron nanoparticles and algae on the sustainability of broiler production under heat stress conditions.

Background: Natural feed additives in broiler feed contribute to the overall health, productivity, and economic viability of broiler chickens while meeting consumer demands and preferences for natural products. The purpose of this research was to determine the effect of green iron nanoparticles (Nano-Fe) and Halimeda opuntia supplementation in broiler diets on performance, ammonia excretion in excreta, Fe retention in tissues and serum, carcass criteria, and meat quality under hot environmental conditions. Methods: A total of 256 one-day-old male Ross 308 broiler chicks were randomly assigned to one of four feeding treatments for 42 days. Each treatment had eight replications, with eight chicks per replicate. The treatments were Negative control (CON), positive control (POS) supplemented with 1 g/kg Halimeda opuntia as a carrier, POS + 20 mg/kg Nano-Fe (NFH1), POS + 40 mg/kg Nano-Fe (NFH2). Results: When compared to CON and POS, dietary Nano-Fe up to 40 mg/kg enhanced (p < 0.001) growth performance in terms of body weight (BW), body weight gain (BWG), and feed conversion ratio (FCR). Nano-Fe had the highest BWG and the most efficient FCR (linear, p < 0.01, and quadratic, p < 0.01) compared to POS. Without affecting internal organs, the addition of Nano-Fe and POS enhanced dressing and reduced (p < 0.001) abdominal fat compared to control (CON). Notably, the water-holding capacity of breast and leg meat was higher (p < 0.001), and cooking loss was lower in broilers given Nano-Fe and POS diets against CON. In comparison to POS, the ammonia content in excreta dropped linearly as green Nano-Fe levels increased. When compared to CON, increasing levels of Nano-Fe levels boosted Fe content in the breast, leg, liver, and serum. The birds fed on POS showed better performance than the birds fed on CON. Conclusion: Green Nano-Fe up to 40 mg/kg fed to broiler diets using 1 g/kg Halimeda opuntia as a carrier or in single can be utilized as an efficient feed supplement for increasing broiler performance, Fe retentions, carcass characteristics, meat quality, and reducing ammonia excretions, under hot conditions.

Alleviating cobalt and lead toxicity in rice using zero valent iron (Fe°) amendments.

Simultaneous impact of zero valent iron (Fe°) and rice cultivar on uptake, translocation, and bioaccumulation of cobalt (Co) and lead (Pb) in rice (Oryza sativa L.) was investigated to alleviate Co and Pb toxicity in rice. Kilombero and Faya rice cultivars, amended with Fe° dosages of 0, 6.20, and 12.40 g Fe° kg-1 soil, were cultivated under continuous flooding in pots in a greenhouse. Shoot and grain-Co and Pb concentrations were determined using inductively coupled plasma mass spectrometry (ICP-MS). For Co, amending Faya rice with at least 6.20 g Fe° kg-1 reduced grain-Co accumulation by 33% or more compared to control plants (F = 17.5; p < 0.001) while inconsistent results were obtained for Kilombero. For Pb, Faya also accumulated more than 39% less grain-Pb than control plants (272 µg kg-1) while Kilombero accumulated more than 55% less grain-Pb than control plants under the same conditions. Despite reducing grain-Pb accumulation in both cultivar, Fe amendments of at least 6.20 g Fe° kg-1 reduced grain-Pb accumulation with greater magnitude in Kilombero (55%) than in Faya (39%). Nonetheless, Fe amendments inhibited greater shoots-Co and Pb translocation (≥32%) to grains in Faya compared to Kilombero (≤20%). The work provides a novel promising agronomical practice of reducing Co and Pb bioaccumulation in rice.

Similarities and differences in iron homeostasis strategies between graminaceous and nongraminaceous plants.

Iron (Fe) homeostasis is essential for both plant development and human nutrition. The maintenance of Fe homeostasis involves a complex network in which Fe signaling nodes and circuits coordinate tightly Fe transporters, ferric reductases, H+ -ATPases, low-molecular-mass metal chelators, and transporters of chelators and Fe-chelate complexes. Early-stage studies have revealed different strategies for Fe homeostasis between graminaceous and nongraminaceous plants. Recent progress has refreshed our understanding of previous knowledge, especially on the uptake, phloem transport and systemic signaling of Fe. This review attempts to summarize recent exciting and potentially influential studies on the various routes of Fe uptake and distribution in plants, focusing on breakthroughs that have changed our understanding of plant Fe nutrition.

A GATA-type transcription factor SreA affects manganese susceptibility by regulating the expression of iron uptake-related genes.

SreA has been identified as a GATA-type transcription factor that represses iron uptake to avoid iron excess during iron sufficiency. However, knowledge about whether SreA also affects the homeostasis of other divalent metal ions is limited. In this study, by screening Aspergillus fumigatus transcription factor deletion mutant libraries, we demonstrate that the sreA deletion mutant shows the greatest tolerance to MnCl2 among the tested divalent metal ions. Fe and Mn stimuli are able to enhance the expression of SreA with the different time-dependent manner, while the expression of SreA contributes to Mn2+ tolerance. Lack of SreA results in abnormally increased expression of a series of siderophore biosynthesis genes and iron transport-related genes, especially under MnCl2 treatment. Further mechanistic exploration indicated that lack of SreA exacerbates abnormal iron uptake, and iron excess inhibits cellular Mn content; thus, deletion of sreA results in Mn tolerance. Thus, findings in this study have demonstrated a new unexplored function for the transcription factor SreA in regulation of the Mn2+ tolerance.

[Effects of Iron Intensity-regulated Root Microbial Community Structure and Function on Cadmium Accumulation in Rice].

Exploring the effects of exogenous iron (Fe) on cadmium (Cd) in rice is of great significance for ensuring food security. The accumulation of Cd and the changes in the microbial community structure in rice roots under three Fe concentrations (5, 50, and 500 µmol·L-1 EDTA-Na2Fe) were studied through a hydroponic experiment. The results showed that the increase in the environmental Fe concentration promoted the formation of iron plaque on the rice roots, and both Fe-deficiency and Fe-sufficiency would enhance the adsorption and fixation of Cd on the root surface. Compared with that of normal Fe levels (50 µmol·L-1), Fe deficiency increased Cd accumulation in rice roots and shoots by 49.76% and 15.68%, respectively. Although Fe sufficiency also increased Cd accumulation in the roots by 18.39%, the Cd concentration in shoots was significantly reduced by 35.95% compared with that of the normal Fe. 16S rRNA high-throughput sequencing was used to determine the root microbial community structure, and through PCA, LEfSe, and RDA analysis, it was found that compared with normal Fe, an Fe-deficient environment reduced the abundance and uniformity of root microbes. Proteobacteria and Bacteroidetes at the phylum level were the dominant flora, Fe deficiency inhibited the increase in the relative abundance of Bacteroidetes, and high-concentration Fe reduced the relative abundance of Proteobacteria. At the genus level, the relative abundance of functional microorganisms Ensifer, Rhodopila, Bdellovibrio, and Dyella were different under different Fe environments, which may have affected the absorption and accumulation of Cd by rice by affecting the formation of Fe plaque on the root and other biochemical processes. In addition, the effect of an Fe-deficient environment on microbial functions was higher than that of the Fe sufficient environment. This study investigated the changes in the rice root microbial community structure and the ability of rice to absorb and transport Cd under different Fe environments, which provided a theoretical basis and an important reference for the inhibition of Fe on Cd accumulation in rice in Cd-polluted paddy soil in southern China.

Desulfoferrobacter suflitae gen. nov., sp. nov., a novel sulphate-reducing bacterium in the Deltaproteobacteria capable of autotrophic growth with hydrogen or elemental iron.

A mesophilic sulphate-reducing micro-organism, able to grow chemolithoautotrophically with H2/CO2 (20 : 80) and with elemental iron as a sole electron donor, was isolated from a consortium capable of degrading long-chain paraffins and designated strain DRH4T. Cells were oval shaped often with bright refractile cores and occurred singly or in pairs. The cells formed pili. Strain DRH4T could grow chemolithoautotrophically with H2/CO2 or elemental iron and chemoorganotrophically utilizing a number of organic substrates, such as fatty acids from formate to octanoate (C1-C8). Sulphate and thiosulphate served as terminal electron acceptors, but sulphite and nitrate did not. Optimal growth was observed from 37 to 40 °C and pH from 6.5 to 7.2. Strain DRH4T did not require NaCl for growth and could proliferate under a broad range of salinities from freshwater (1 g l-1 NaCl) to seawater (27 g l-1 NaCl) conditions. The genomic DNA G+C content was 54.46 mol %. Based on 16S rRNA gene sequence analysis. strain DRH4T was distinct from previously described Deltaproteobacteria species exhibiting the closest affiliation to Desulforhabdus amnigena ASRB1T, Syntrophobacterium sulfatireducens TB8106T and Desulfovirga adipica 12016T with 93.35, 93.42 and 92.85 % similarity, respectively. Strain DRH4T showed significant physiological differences with the aforementioned organisms. Based on physiological differences and phylogenetic comparisons, we propose to classify DRH4T as the type strain (=DSM 113 455T=JCM 39 248T) of a novel species of a new genus with the name Desulfoferrobacter suflitae gen. nov., sp. nov.

Genome-Wide Association Analysis Reveals the Genetic Basis of Iron-Deficiency Stress Tolerance in Maize.

Iron (Fe) is an essential trace element for almost all organisms and is often the major limiting nutrient for normal growth. Fe deficiency is a worldwide agricultural problem, which affects crop productivity and product quality. Understanding the Fe-deficiency response in plants is necessary for improving both plant health and the human diet. In this study, Fe-efficient (Ye478) and Fe-inefficient maize inbred lines (Wu312) were used to identify the genotypic difference in response to low Fe stress during different developmental stages and to further determine the optimal Fe-deficient Fe(II) supply level which leads to the largest phenotypic difference between Ye478 and Wu312. Then, genome-wide association analysis was performed to further identify candidate genes associated with the molecular mechanisms under different Fe nutritional statuses. Three candidate genes involved in Fe homeostasis of strategy II plants (strategy II genes) were identified, including ZmDMAS1, ZmNAAT1, and ZmYSL11. Furthermore, candidate genes ZmNAAT1, ZmDMAS1, and ZmYSL11 were induced in Fe-deficient roots and shoots, and the expression of ZmNAAT1 and ZmDMAS1 responded to Fe deficiency more in shoots than in roots. Beyond that, several genes that may participate in Fe homeostasis of strategy I plants (strategy I genes) were identified, which were either encoding Fe transporters (ZmIRT1 and ZmZIP4), or acting as essential ethylene signal transducers (ZmEBF1). Interestingly, ZmIRT1, ZmZIP4, and ZmEBF1 were significantly upregulated under low Fe stress, suggesting that these genes may be involved in Fe-deficiency tolerance in maize which is considered as strategy II plant. This study demonstrates the use of natural variation in the association population to identify important genes associated with Fe-deficiency tolerance and may further provide insights for understanding the molecular mechanism underlying the tolerance to Fe-deficiency stress in maize.

Whole genome re-sequencing of indian wheat genotypes for identification of genomic variants for grain iron and zinc content.

BACKGROUND: Whole-genome sequencing information which is of abundant significance for genetic evolution, and breeding of crops. Wheat (Triticum spp) is most widely grown and consumed crops globally. Micronutrients are very essential for healthy development of human being and their sufficient consumption in diet is essential for various metabolic functions. Biofortification of wheat grains with iron (Fe) and zinc (Zn) has proved the most reliable and effective way to combat micronutrient associated deficiency. Genetic variability for grain micronutrient could provide insight to dissect the traits. METHODS AND RESULTS: In the current study, 1300 wheat lines were screened for grain Fe and Zn content, out of which only five important Indian wheat genotypes were selected on the basis of Fe and Zn contents. These lines were multiplied during at the National Agri-Food Biotechnology Institute (NABI) and re-sequenced to identify genomic variants in candidate genes for Fe and Zn between the genotypes. Whole genome sequencing generated Ì´ 12 Gb clean data. Comparative genome analysis identified 254 genomic variants in the candidate genes associated with deleterious effect on protein function. CONCLUSIONS: The present study demonstrated the fundamental in understanding the genomic variations for Fe and Zn enrichment to generate healthier wheat grains.

Identification of Quantitative Trait Loci Associated With Iron Deficiency Tolerance in Maize.

Iron (Fe) is a limiting factor in crop growth and nutritional quality because of its low solubility. However, the current understanding of how major crops respond to Fe deficiency and the genetic basis remains limited. In the present study, Fe-efficient inbred line Ye478 and Fe-inefficient inbred line Wu312 and their recombinant inbred line (RIL) population were utilized to reveal the physiological and genetic responses of maize to low Fe stress. Compared with the Fe-sufficient conditions (+Fe: 200 µM), Fe-deficient supply (-Fe: 30 µM) significantly reduced shoot and root dry weights, leaf SPAD of Fe-efficient inbred line Ye478 by 31.4, 31.8, and 46.0%, respectively; decreased Fe-inefficient inbred line Wu312 by 72.0, 45.1, and 84.1%, respectively. Under Fe deficiency, compared with the supply of calcium nitrate (N1), supplying ammonium nitrate (N2) significantly increased the shoot and root dry weights of Wu312 by 37.5 and 51.6%, respectively; and enhanced Ye478 by 23.9 and 45.1%, respectively. Compared with N1, N2 resulted in a 70.0% decrease of the root Fe concentration for Wu312 in the -Fe treatment, N2 treatment reduced the root Fe concentration of Ye478 by 55.8% in the -Fe treatment. These findings indicated that, compared with only supplying nitrate nitrogen, combined supply of ammonium nitrogen and nitrate nitrogen not only contributed to better growth in maize but also significantly reduced Fe concentration in roots. In linkage analysis, ten quantitative trait loci (QTLs) associated with Fe deficiency tolerance were detected, explaining 6.2-12.0% of phenotypic variation. Candidate genes considered to be associated with the mechanisms underlying Fe deficiency tolerance were identified within a single locus or QTL co-localization, including ZmYS3, ZmPYE, ZmEIL3, ZmMYB153, ZmILR3 and ZmNAS4, which may form a sophisticated network to regulate the uptake, transport and redistribution of Fe. Furthermore, ZmYS3 was highly induced by Fe deficiency in the roots; ZmPYE and ZmEIL3, which may be involved in Fe homeostasis in strategy I plants, were significantly upregulated in the shoots and roots under low Fe stress; ZmMYB153 was Fe-deficiency inducible in the shoots. Our findings will provide a comprehensive insight into the physiological and genetic basis of Fe deficiency tolerance.

Mapping of the Quantitative Trait Loci and Candidate Genes Associated With Iron Efficiency in Maize.

Iron (Fe) is a mineral micronutrient for plants, and Fe deficiency is a major abiotic stress in crop production because of its low solubility under aerobic and alkaline conditions. In this study, 18 maize inbred lines were used to preliminarily illustrate the physiological mechanism underlying Fe deficiency tolerance. Then biparental linkage analysis was performed to identify the quantitative trait loci (QTLs) and candidate genes associated with Fe deficiency tolerance using the recombinant inbred line (RIL) population derived from the most Fe-efficient (Ye478) and Fe-inefficient (Wu312) inbred lines. A total of 24 QTLs was identified under different Fe nutritional status in the Ye478 × Wu312 RIL population, explaining 6.1-26.6% of phenotypic variation, and ten candidate genes were identified. Plants have evolved two distinct mechanisms to solubilize and transport Fe to acclimate to Fe deficiency, including reduction-based strategy (strategy I) and chelation-based strategy (strategy II), and maize uses strategy II. However, not only genes involved in Fe homeostasis verified in strategy II plants (strategy II genes), which included ZmYS1, ZmYS3, and ZmTOM2, but also several genes associated with Fe homeostasis in strategy I plants (strategy I genes) were identified, including ZmFIT, ZmPYE, ZmILR3, ZmBTS, and ZmEIN2. Furthermore, strategy II gene ZmYS1 and strategy I gene ZmBTS were significantly upregulated in the Fe-deficient roots and shoots of maize inbred lines, and responded to Fe deficiency more in shoots than in roots. Under Fe deficiency, greater upregulations of ZmYS1 and ZmBTS were observed in Fe-efficient parent Ye478, not in Fe-inefficient parent Wu312. Beyond that, ZmEIN2 and ZmILR3, were found to be Fe deficiency-inducible in the shoots. These findings indicate that these candidate genes may be associated with Fe deficiency tolerance in maize. This study demonstrates the use of natural variation to identify important Fe deficiency-regulated genes and provides further insights for understanding the response to Fe deficiency stress in maize.

Development of zerovalent iron and titania (Fe0/TiO2) composite for oxidative degradation of dichlorophene in aqueous solution: synergistic role of peroxymonosulfate (HSO5-).

Binary composite of zerovalent iron and titanium dioxide (Fe0/TiO2) was synthesized for the catalytic removal of dichlorophene (DCP) in the presence of peroxymonosulfate (PMS). The as-prepared composite (Fe0/TiO2) exhibits synergistic effect and enhanced properties like improved catalytic activity of catalyst and greater magnetic property for facile recycling of catalyst. The results showed that without addition of PMS at reaction time of 50 min, the percent degradation of DCP by TiO2, Fe0, and Fe0/TiO2 was just 5%, 11%, and 12%, respectively. However, with the addition of 0.8 mM PMS, at 10 min of reaction time, the catalytic degradation performance of Fe0, TiO2, and Fe0/TiO2 was significantly improved to 82%, 18%, and 88%, respectively. The as-prepared catalyst was fully characterized to evaluate its structure, chemical states, and morphology. Scanning electron microscopy results showed that in composite TiO2 causes dispersion of agglomerated iron particles which enhances porosity and surface area of the composites and X-ray diffraction (XRD), energy dispersive X-ray (EDX), and Fourier-transform infrared (FTIR) results revealed successful incorporation of Fe0, and oxides of Fe and TiO2 in the composite. The adsorption-desorption analysis verifies that the surface area of Fe0/TiO2 is significantly larger than bare Fe0 and TiO2. Moreover, the surface area, particle size, and crystal size of Fe0/TiO2 was surface area = 85 m2 g-1, particle size = 0.35 µm, and crystal size = 0.16 nm as compared to TiO2 alone (surface area = 22 m2 g-1, particle size = 4.25 µm, and crystal size = 25.4 nm) and Fe0 alone (surface area = 65 m2 g-1, particle size = 0.9 µm, and crystal size = 7.87 nm). The as-synthesized material showed excellent degradation performance in synthesized wastewater as well. The degradation products and their toxicities were evaluated and the resulted degradation mechanism was proposed accordingly. The toxicity values decreased in order of DP1 > DP5 > DP2 > DP3 > DP4 and the LC50 values toward fish for 96-h duration decreased from 0.531 to 67.2. This suggests that the proposed technology is an excellent option for the treatment of antibiotic containing wastewater.

Stable immobilization of uranium in iron containing environments with microbial consortia enriched via two steps accumulation method.

The stable stabilization of uranium (U) in iron (Fe) containing environments is restricted by the reoxidation of UO2. In the current study, based on air reoxidation tests, we propose a novel two steps accumulation method to enrich microbial consortia from paddy soil. The constructed microbial consortia, denoted as the Fe-U bacteria, can co-precipitate U and Fe to form stable Fe-U solids. Column experiments running for 4 months demonstrated the production of U(IV)-O-Fe(II) precipitates containing maximum of 39.51% uranium in the presence of Fe-U bacteria. The reoxidation experiments revealed the U(IV)-O-Fe(II) precipitates were more stable than UO2. 16S rDNA high throughput sequencing analysis demonstrated that Acinetobacter and Stenotrophomonas were responsible for Fe and U precipitation, while, Caulobacteraceae and Aminobacter were crucial for the formation of U(VI)-PO4 chemicals. The proposed two steps accumulation method has an extraordinary application potential in stable immobilization of uranium in iron containing environments.

A reciprocal inhibitory module for Pi and iron signaling.

Phosphorous (P) and iron (Fe), two essential nutrients for plant growth and development, are highly abundant elements in the earth's crust but often display low availability to plants. Due to the ability to form insoluble complexes, the antagonistic interaction between P and Fe nutrition in plants has been noticed for decades. However, the underlying molecular mechanism modulating the signaling and homeostasis between them remains obscure. Here, we show that the possible iron sensors HRZs, the iron deficiency-induced E3 ligases, could interact with the central regulator of phosphate (Pi) signaling, PHR2, and prompt its ubiquitination at lysine residues K319 and K328, leading to its degradation in rice. Consistent with this, the hrzs mutants displayed a high Pi accumulation phenotype. Furthermore, we found that iron deficiency could attenuate Pi starvation signaling by inducing the expression of HRZs, which in turn trigger PHR2 protein degradation. Interestingly, on the other hand, rice PHRs could negatively regulate the expression of HRZs to modulate iron deficiency responses. Therefore, PHR2 and HRZs form a reciprocal inhibitory module to coordinate Pi and iron signaling and homeostasis in rice. Taken together, our results uncover a molecular link between Pi and iron master regulators, which fine-tunes plant adaptation to Pi and iron availability in rice.

Higher zero valent iron soil amendments dosages markedly inhibit accumulation of As in Faya and Kilombero cultivars compared to Cd.

Impact of zero valent iron (Fe°) amendment on grain-yield (GY) and grain-As and Cd accumulation in rice (Oryza sativa L.) cultivars Kilombero and Faya were investigated. Rice plants were amended with Fe° dosages of 0, 3.1, 6.2, and 12.4 g Fe°/kg soil in pots in greenhouse experiments under continuous flooding water regime. GY in each treatment was determined at maturity, grain-As and Cd and arsenic species concentrations were determined using ICP-MS and HPLC tandem ICP-MS respectively. Mean GY in Faya (5.5 ± 1.0 g/plant) and Kilombero (4.2 ± 0.4 g/plant) amended with at least 6.2 g Fe°/kg soil were at least 57% and 22% respectively significantly higher (F = 11; p = 0.003) than that in controls (3.7 ± 0.6 and 3.4 ± 0.4 g/plant). For As bioaccumulation, mean grain-As concentration in Faya T2 (≤227 ± 32 µg/kg) and Kilombero (≤218 ± 25 µg/kg) amended with at least 6.2 g Fe°/kg soil in were at least 83% and 77% respectively significantly lower (F = 7; p = 0.004) than that in controls (973 ± 43 µg/kg and 1278 ± 208 µg/kg). Mean grain-Cd concentrations in Faya (10 ± 2 µg/kg) and Kilombero (13 ± 3 µg/kg) amended with corresponding Fe° dosages were at least 26% and 39% significantly lower (F = 4; p < 0.05) than that in controls (18 ± 3 and 23 ± 1 µg/kg). Results indicated that amending Kilombero with at least 6.2 g/kg Fe° effectively optimally regulated both grain-As and Cd accumulation to values lower than the European Commission's legislated maximum contaminant limits (MCL) of 200 µg/kg without negating grain yield benefits. Our results suggest that bioaccumulation of both As and Cd in rice grains may be completely circumvented by adopting cultivar-specific Fe° amendment dosage.

Force Field Parameters for Fe2+4S2-4 Clusters of Dihydropyrimidine Dehydrogenase, the 5-Fluorouracil Cancer Drug Deactivation Protein: A Step towards In Silico Pharmacogenomics Studies.

The dimeric dihydropyrimidine dehydrogenase (DPD), metalloenzyme, an adjunct anti-cancer drug target, contains highly specialized 4 × Fe2+4S2-4 clusters per chain. These clusters facilitate the catalysis of the rate-limiting step in the pyrimidine degradation pathway through a harmonized electron transfer cascade that triggers a redox catabolic reaction. In the process, the bulk of the administered 5-fluorouracil (5-FU) cancer drug is inactivated, while a small proportion is activated to nucleic acid antimetabolites. The occurrence of missense mutations in DPD protein within the general population, including those of African descent, has adverse toxicity effects due to altered 5-FU metabolism. Thus, deciphering mutation effects on protein structure and function is vital, especially for precision medicine purposes. We previously proposed combining molecular dynamics (MD) and dynamic residue network (DRN) analysis to decipher the molecular mechanisms of missense mutations in other proteins. However, the presence of Fe2+4S2-4 clusters in DPD poses a challenge for such in silico studies. The existing AMBER force field parameters cannot accurately describe the Fe2+ center coordination exhibited by this enzyme. Therefore, this study aimed to derive AMBER force field parameters for DPD enzyme Fe2+ centers, using the original Seminario method and the collation features Visual Force Field Derivation Toolkit as a supportive approach. All-atom MD simulations were performed to validate the results. Both approaches generated similar force field parameters, which accurately described the human DPD protein Fe2+4S2-4 cluster architecture. This information is crucial and opens new avenues for in silico cancer pharmacogenomics and drug discovery related research on 5-FU drug efficacy and toxicity issues.

DNA methylation is involved in acclimation to iron-deficiency in rice (Oryza sativa).

Iron (Fe) is an essential micronutrient in plants, and Fe limitation significantly affects plant growth, yield and food quality. While many studies have reported the transcriptomic profile and pursue molecular mechanism in response to Fe limitation, little is known if epigenetic factors play a role in response to Fe-deficiency. In this study, whole-genome bisulfite sequencing analysis, high-throughput RNA-Seq of mRNA, small RNA and transposable element (TE) expression with root and shoot organs of rice seedlings under Fe-sufficient and Fe-deficient conditions were performed. The results showed that widespread hypermethylation, especially for the CHH context, occurred after Fe-deficiency. Integrative analysis of methylation and transcriptome revealed that the transcript abundance of Fe-deficiency-induced genes was negatively correlated with nearby TEs and positively with the 24-nucleotide siRNAs. The ability of methylation to affect the physiology and molecular response to Fe-deficiency was tested using an exogenous DNA methyltransferase inhibitor (5-azacytidine), and genetically using a mutant for domains rearranged methyltransferase 2 (DRM2), that lacks CHH methylation. Both approaches resulted in decreased growth and Fe content in rice plants. Thus, alterations in specific methylation patterns, directed by siRNAs, play an important role in acclimation of rice to Fe-deficient conditions. Furthermore, comparison with other reports suggests this may be a universal mechanism to acclimate to limited nutrient availability.

Biocompatibility nanoprobe of MXene N-Ti3C2 quantum dot/Fe3+ for detection and fluorescence imaging of glutathione in living cells.

MXene quantum dots have attracted much attention due to their great optical performance and excellent water solubility. Glutathione (GSH) plays a key role in living cells. In this study, a biocompatibility nanoprobe was prepared for detecting intracellular GSH based on MXene N-Ti3C2 quantum dots (N-Ti3C2 QDs). The N-Ti3C2 QDs act as the fluorescence reporters and the ferric iron (Fe3+) as the quenchers based on nonradiative electron-hole annihilation. When Fe3+ encounters the amino group of N-Ti3C2 QDs, the electrons of N-Ti3C2 QDs in the excited state will transfer to the half-filled 3d orbitals of Fe3+, leading to the fluorescence quenching of N-Ti3C2 QDs. When the N-Ti3C2 QDs/Fe3+ nanoprobe acts on the cancer cell MCF-7, the abundant GSH in the cancer cells can reduce Fe3+ to Fe2+, which will restore the fluorescence of N-Ti3C2 QDs. The N-Ti3C2 QDs/Fe3+ nanoprobe displays a high sensitivity for GSH with a detection limit of 0.17 µM in range of 0.5-100 µM. It becomes a promising probe for detecting and showing cellular imaging of GSH in MCF-7 cells. The N-Ti3C2 QDs/Fe3+ nanoprobe might provide a new way for imaging-guided precision cancer diagnosis.

Enhancement of Photosynthetic Iron-Use Efficiency Is an Important Trait of Hordeum vulgare for Adaptation of Photosystems to Iron Deficiency.

Leaf iron (Fe) contents in Fe-deficiency-tolerant plants are not necessarily higher than that in Fe-deficiency-susceptible ones, suggesting an unknown mechanism involved in saving and allowing the efficient use of minimal Fe. To quantitatively evaluate the difference in Fe economy for photosynthesis, we compared the ratio of CO2 assimilation rate to Fe content in newly developed leaves as a novel index of photosynthetic iron-use efficiency (PIUE) among 23 different barley (Hordeum vulgare L.) varieties. Notably, varieties originating from areas with alkaline soil increased PIUE in response to Fe-deficiency, suggesting that PIUE enhancement is a crucial and genetically inherent trait for acclimation to Fe-deficient environments. Multivariate analyses revealed that the ability to increase PIUE was correlated with photochemical quenching (qP), which is a coefficient of light energy used in photosynthesis. Nevertheless, the maximal quantum yield of photosystem II (PSII) photochemistry, non-photochemical quenching, and quantum yield of carbon assimilation showed a relatively low correlation with PIUE. This result suggests that the ability of Fe-deficiency-tolerant varieties of barley to increase PIUE is related to optimizing the electron flow downstream of PSII, including cytochrome b6f and photosystem I.

Generation Mean Analysis Reveals the Predominant Gene Effects for Grain Iron and Zinc Contents in Pearl Millet.

Pearl millet [Pennisetum glaucum (L.) R. Br.] is a climate-resilient dryland cereal that has been identified as a potential staple food crop that can contribute to alleviating micronutrient malnutrition, particularly with respect to grain iron (Fe) and zinc (Zn) contents, in Sub-Saharan Africa and India. In this regard, an understanding of the inheritance pattern of genes involved in Fe and Zn contents is vital for devising appropriate breeding methods to genetically enhance their levels in grains. In this study, we aimed to determine the genetic effects underlying such inheritance and their interactions based on the generation mean analyses. Four experimental crosses and their six generations (P1, P2, F1, BCP1, BCP2, and F2) were independently evaluated in a compact family block design in 2017 rainy and 2018 summer seasons. ANOVA revealed highly significant mean squares (p < 0.01) among different generations for grain Fe and Zn contents. Six-parameter generation mean analyses revealed a predominance of additive genetic effect and a significant (p < 0.05) additive × dominant interaction for the grain Fe content. The additive genetic effect for the grain Zn content was also highly significant (p < 0.01). However, interaction effects contributed minimally with respect to most of the crosses for the grain Zn content and hence we assume that a simple digenic inheritance pattern holds true for it. Furthermore, we established that narrow-sense heritability was high for the grain Fe content (>61.78%), whereas it was low to moderate for the grain Zn content (30.60-59.04%). The lack of superior parent heterosis coupled with non-significant inbreeding depression for Fe and Zn contents in grains further confirmed the predominance of an additive genetic effect. These findings will contribute to strategizing a comprehensive breeding method to exploit the available variability of grain Fe and Zn contents for the development of biofortified hybrids of pearl millet.

Synergistic Zerovalent Iron (Fe0) and Microbiological Trichloroethene and Perchlorate Reductions Are Determined by the Concentration and Speciation of Fe.

Trichloroethene (TCE) and perchlorate (ClO4-) are cocontaminants at multiple Superfund sites. Fe0 is often used during TCE bioremediation with Dehalococcoides mccartyi to establish anoxic conditions in the aquifer. However, the synergy between Fe0 abiotic reactions and microbiological TCE and ClO4- reductions is poorly understood and seldom addressed in the literature. Here, we investigated the effects of Fe0 and its oxidation product, Fe2+, at field-relevant concentrations in promoting microbial TCE and ClO4- reductions. Using semibatch microcosms with a Superfund site soil and groundwater, we showed that the high Fe0 concentration (16.5 g L-1) expected during Fe0in situ injection mostly yielded TCE abiotic reduction to ethene/ethane. However, such concentrations obscured dechlorination by D. mccartyi, impeded ClO4- reduction, and enhanced SO42- reduction and methanogenesis. Fe2+ at 0.25 g L-1 substantially delayed conversion of TCE to ethene when compared to no-Fe controls. A low concentration of aged-Fe0 synergistically promoted microbiological TCE dechlorination to ethene while achieving complete ClO4- reduction. Collectively, these results illustrate scenarios relevant at or downstream of Fe0 injection zones when Fe0 is used to facilitate microbial dechlorination. Results also underscore the potential detrimental effects of Fe0 and bioaugmentation cultures coinjection for in situ treatment of chlorinated ethenes and ClO4-.