Zinc Uptake Research Articles

The efflux system CdfX exports zinc that cannot be transported by ZntA in Cupriavidus metallidurans.

Cupriavidus metallidurans is able to survive exposure to high concentrations of transition metals, but is also able to grow under metal starvation conditions. A prerequisite of cellular zinc homeostasis is a flow equilibrium combining zinc uptake and efflux processes. The mutant strain ∆e4 of the parental plasmid-free strain AE104 with a deletion of all four chromosomally encoded genes of previously known efflux systems ZntA, CadA, DmeF, and FieF was still able to efflux zinc in a pulse-chase experiment, indicating the existence of a fifth efflux system. The gene cdfX, encoding a protein of the cation diffusion facilitator (CDF) family, is located in proximity to the cadA gene, encoding a P-type ATPase. Deletion of cdfX in the ∆e4 mutant resulted in a further decrease in zinc resistance. Pulse-chase experiments with radioactive 65Zn(II) and stable-isotope-enriched 67Zn(II) provided evidence that CdfX was responsible for the residual zinc efflux activity of the mutant strain ∆e4. Reporter gene fusions with cdfX-lacZ indicated that the MerR-type regulator ZntR, the main regulator of zntA expression, was responsible for zinc- and cadmium-dependent upregulation of cdfX expression, especially in mutant cells lacking one or both of the previously characterized efflux systems, ZntA and CadA. Expression of zntR also proved to be controlled by ZntR itself as well as by zinc and cadmium availability. These data indicate that the cdfX-cadA region provides C. metallidurans with a backup system for the zinc-cadmium-exporting P-type ATPase ZntA, with CdfX exporting zinc and CadA cadmium.IMPORTANCEBacteria have evolved the ability to supply the important trace element zinc to zinc-dependent proteins, despite external zinc concentrations varying over a wide range. Zinc homeostasis can be understood as adaptive layering of homeostatic systems, allowing coverage from extreme starvation to extreme resistance. Central to zinc homeostasis is a flow equilibrium of zinc comprising uptake and efflux reactions, which adjusts the cytoplasmic zinc content. This report describes what happens when an imbalance in zinc and cadmium concentrations impairs the central inner-membrane zinc efflux system for zinc by competitive inhibition for this exporter. The problem is solved by activation of Cd-exporting CadA or Zn-exporting CdfX as additional efflux systems.

Xanthomonas axonopodis pv. glycines Zur is involved in pathogenicity in host and hypersensitive responses in nonhosts

The zinc uptake regulator (Zur) has highly conserved sequences in the plant pathogen Xanthomonas, while its functions are diverse in different strains or races. To elucidate the functions of Zur in Xanthomonas axonopodis pv. glycines (Xag), we constructed a zur-deleted mutant (Δzur) by homologous recombination. Compared with the wild type, Δzur demonstrated reduced pathogenicity in the host soybean and reduced ability to trigger hypersensitive responses (HR) in nonhosts such as tobacco, tomato, chili pepper, and eggplant. Additionally, the deletion of zur significantly enhanced Xag's sensitivity to Zn2+, Fe3+, and Cu2+, induced an imbalance in intracellular zinc homeostasis, decreased extracellular polysaccharide (EPS) production, and down-regulated the expression of extracellular hydrolases (cellulase, endo-glucanase, amylase, and protease). Functional complementation restored the defective properties of Δzur to the wild-type levels. The qRT-PCR results showed that zur expression was remarkably induced by Zn2+. Moreover, the deletion of zur evidently reduced the expression levels of hrp representative genes (hrpB1, hrpD6, hrpE, hrcV, and hrcC), extracellular hydrolase encoding genes (engXCA, egl2, pro1, pro2, pro8, pro11, and alpha1), and EPS synthesis genes (gumB, gumD, gumK, gumM, gumG, and gumH) relative to the wild type. In summary, the results suggested that Zur may be involved in pathogenicity in the host soybean and in triggering HR in nonhosts of Xag by regulating the synthesis of virulence factors and the expression of hrp genes. This laid a foundation for further analysis of the mechanism of Zur in Xanthomonas-plant interaction.

Enhancing Iron and Zinc Uptake in Spring Wheat Through Commercial Arbuscular Mycorrhizal Fungi Inoculation under Different Soil Phosphorus Addition Levels

Improving the concentrations and bioavailability of micronutrients, especially iron (Fe) and zinc (Zn), in crop grains is important to alleviate their deficiencies in humans. Inoculating crops with arbuscular mycorrhizal fungi (AMF) can potentially enhance soil nutrient supply and crop yield, but the effectiveness is influenced by soil factors, particularly soil phosphorus (P) availability. A greenhouse pot experiment was conducted to evaluate the effect of a commercial AMF product on spring wheat (Triticum aestivum L.) yield and grain concentrations of Zn and Fe under different soil P addition levels (0, 5 and 20 mg P kg-1 dry soil). Results showed that AMF inoculation significantly increased root colonization rate of wheat across all P addition levels. Wheat growth, as evidenced by dry weights of shoot and grain, was significantly enhanced by AMF and high P addition treatments. AMF inoculation did not affect grain Zn concentration, but significantly increased grain Fe concentration compared to the un-inoculated control. As expected, P addition resulted in a significant reduction in grain concentrations of Fe and Zn, primarily due to a growth dilution effect. An integrated analysis using the radar plot concludes that AMF inoculation is most effective in increasing crop yield and grain micronutrient concentrations when soil P levels are low. Importantly, while adequate P supply is crucial for maintaining crop productivity, it may decrease grain micronutrient availability without complementary strategies.

Neuronal SLC39A8 deficiency impairs cerebellar development by altering manganese homeostasis.

Solute carrier family 39, member 8 (SLC39A8), is a transmembrane transporter that mediates the cellular uptake of zinc, iron, and manganese (Mn). Human genetic studies document the involvement of SLC39A8 in Mn homeostasis, brain development, and function. However, the role and pathophysiological mechanisms of SLC39A8 in the central nervous system remain elusive. We generated Slc39a8 neuron-specific knockout (Slc39a8-NSKO) mice to study SLC39A8 function in neurons. The Slc39a8-NSKO mice displayed markedly decreased Mn levels in the whole brain and brain regions, especially the cerebellum. Radiotracer studies using 54Mn revealed that Slc39a8-NSKO mice had impaired brain uptake of Mn. Slc39a8-NSKO cerebellums exhibited morphological defects and abnormal dendritic arborization of Purkinje cells. Reduced neurogenesis and increased apoptotic cell death occurred in the cerebellar external granular layer of Slc39a8-NSKO mice. Brain Mn deficiency in Slc39a8-NSKO mice was associated with motor dysfunction. Unbiased RNA-Seq analysis revealed downregulation of key pathways relevant to neurodevelopment and synaptic plasticity, including cAMP signaling pathway genes. We further demonstrated that Slc39a8 was required for the optimal transcriptional response to the cAMP-mediated signaling pathway. In summary, our study highlighted the essential roles of SLC39A8 in brain Mn uptake and cerebellum development and functions.

Milk osteopontin mediates zinc uptake in intestinal cells in the presence of phytic acid

The bioavailability and the intestinal absorption of the essential mineral zinc are challenged by the food matrix and especially the content of zinc chelating antinutrients. Many milk proteins and peptides affect zinc bioavailability. Osteopontin (OPN) is an acidic and highly phosphorylated whey protein that has been shown to bind calcium, magnesium and iron. Here we report the zinc binding properties of OPN, and the effect of OPN-Zn complexes on zinc absorption in Caco-2 cells. By isothermal titration calorimetry milk OPN was shown to bind approximately 36 zinc ions (KD of ∼70 μM). The binding was mainly mediated by the phosphorylations in the protein. OPN retained zinc bound after in vitro simulated gastrointestinal transit. Interestingly the OPN-Zn complex enhanced zinc bioavailability in the presence of phytic acid, compared to inorganic zinc salts. Zinc uptake mediated by OPN significantly upregulated the gene expression of MT1G and ZnT1 which are crucial proteins involved in preserving enterocyte zinc homoeostasis. These results indicate that OPN could be incorporated into functional foods and infant formulas to increase zinc bioavailability and uptake.

Zinc Biofortification of Selective Colored Rice Cultivars: Improvement of Zinc Uptake, Agronomic Traits, and Nutritional Value

It is difficult for ordinary rice to break the zinc-rich standard. However, employing multiple unique rice cultivar resources through biofortification of agronomic measures to achieve the target is a promising attempt. In this study, a pot experiment was conducted on seven different colored rice cultivars (GFHN 166, GFHN 168, GFHN 169, GH 1, GXHZ, GHSZ, and YXN), aiming to analyze the effect on zinc content, growth, quality, and health risk index when spraying zinc (400 g/ha) on the leaves at the heading age. The result indicated that after foliar biofortification treatment, the zinc content and the zinc accumulation of colored rice grains could reach up to 41.55 mg/kg and 2.28 mg/pot, respectively, increased by 43.92% and 65.22%. In addition, the SPAD value and grain protein content was 42.85 and 8.49%, also increased significantly by 2.15% and 2.91%, respectively. Among these, GXHZ and GHSZ could realize the zinc content of polished rice up to 69.7 mg/kg and 55.4 mg/kg, breaking through the standard of zinc-enrich rice (45 mg/kg). GXHZ plant height increased by 11.22%, and the zinc harvest index (6.44%) and zinc use efficiency (26.79%) were the highest. Meanwhile, the biofortification promoted the SPAD value of GHSZ and the protein content of GFHN 166 by 4.95% and 24.81%, respectively. Foliar-applied zinc at the heading stage is a vital practice to get better agronomic indicators, quality, and grain zinc biofortification of colored rice.

Application of machine learning algorithms for predicting the life-long physiological effects of zinc oxide Micro/Nano particles on Carum copticum

Nanoparticles impose multidimensional effects on living cells that significantly vary among different studies. Machine learning (ML) methods are recommended to elucidate more consistence and predictable relations among the affected parameters. In this study, nine ML algorithms [Support-Vector Regression (SVR), Linear, Bagging, Stochastic Gradient Descent (SGD), Gaussian Process, Random Sample Consensus (RANSAC), Partial Least Squares (PLS), Kernel Ridge, and Random Forest] were applied to evaluate their efficiency in predicting the effects of zinc oxide nanoparticles (ZnO NPs: 0.5, 1, 5, 25, and 125 µM) and microparticles (ZnO MPs: 1, 5, 25, and 125 µM) on Carum copticum. The plant root/shoot biomass; number of leaves, branches, umbellates, and flowers; protein content; reducing sugars; phenolic compounds; chlorophylls (a, b, Total); carotenoids; anthocyanins; H2O2; proline; malondialdehyde (MDA); tissue zinc content; superoxide dismutase (SOD) activity; and media ΔpH were measured and considered input variables. All levels of ZnO MPs treatments increased growth parameters compared to the control (ZnSO4). The highest shoot/root fresh and dry mass were recorded at 5 µM ZnO MPs compared with the control. The root fresh/dry mass under ZnO NPs treatments was more sensitive than shoot parameters. The number of flowers increased by 134 and 79% in MPs and NPs treatments compared to the control, respectively. ZnO NPs reduced protein content by up to 81% in 125 µM NPs compared to ZnSO4. Reducing sugar content increased to 25, 40 and 36% in 5, 25, 125 µM MPs and 67, 68, 26, 26 and 21% in 0.5, 1, 5, 25 and 125 µM NPs treatments, respectively. The pH alteration was more significant under NPs and affected zinc uptake. All levels of ZnO NPs treatments increased growth parameters compared to the control. All ML algorithms showed varied efficiencies in predicting the nonlinear relationships among parameters, with higher efficiency in predicting the behavior of root and shoot dry mass, root fresh weight and number of flowers according to R2 index. The model obtained from SVR with the radial basis function (RBF) kernel was selected as a comprehensive model for predicting and determining the efficacy of the results.

Zinc fortification and legume incorporation in forage based cropping systems: Implications for yield and nutrient dynamics

Aim: To evaluate the synergistic effects of legume intercropping and zinc fortification on forage yield, and plant and soil nutrient dynamics. Methodology: The experiment was laid out in a Factorial Randomized Block Design. Treatment combinations included five cropping systems, i.e., sole maize, sole cowpea, sole soybean, maize + cowpea (2:1), maize + soybean (2:1) and three zinc levels; Zn0= control or no zinc application, Zn1 = 20 kg ZnSO4 ha-1 (basal soil application) and Zn2 = 20 kg ZnSO4 ha-1 (basal soil application) + 0.5% ZnSO4 sprayed twice (30 DAS and 50 DAS). Results: Sole maize recorded highest dry matter (11938 kg ha-1) yield. Soil + foliar zinc application (Zn2) recorded an increase of 37.93 % increase in dry matter yield over control (Zn0). Maize + legumes recorded higher nitrogen uptake. There was an overall increase (122.34%) in zinc uptake from Zn0 to Zn2. Soil + foliar applied Zn increased ZnUE by 27.60 % (619.14 kg) over soil applied Zn (485.19 kg). Zn application increased Zn values of soil to 0.50 ppm with soil application and 0.56 ppm with soil + foliar application from the initial value of 0.36 ppm. Interpretation: Intercropping of legumes and application of 20 kg ZnSO4 as basal soil application plus two foliar applications of 0.5% ZnSO4 at 30 and 50 days after sowing significantly increased forage yield, nutrient uptake and enhanced soil zinc levels. Key words: Cropping systems, Intercropping, Legumes, Nutrient dynamics, Yield, Zn fortification

Genome-wide identification and expression analysis of the ZRT, IRT-like Protein (ZIP) family in Nicotiana tabacum.

Iron (Fe) and Zinc (Zn) are essential micronutrients for plant growth and development. ZIP (ZRT, IRT-like protein) transporters, known for their role in the regulation of Zinc and Iron uptake, are pivotal in facilitating the absorption, transport, and maintenance of Fe/Zn homeostasis in plants. Nicotiana tabacum has been widely used as a model plant for gene function analysis; however, the tobacco ZIP genes have not been identified systematically. In this study, we have identified a comprehensive set of 32 NtZIP genes, which were phylogenetically categorized into three distinct clades. The gene structures, characterized by their exon/intron organization, and the protein motifs are relatively conserved, particularly among genes within the same clade. These NtZIP genes exhibit an uneven distribution across 12 chromosomes. The gene localization analysis revealed the presence of 11 pairs of homeologous locus genes and 7 pairs of tandem duplication genes within the genome. To further explore the functionality of these genes, Real-Time Quantitative Reverse Transcription PCR (qRT-PCR) was employed to assess their expression levels in roots subjected to metal deficiency. The results indicated that certain NtZIP genes are specifically upregulated in response to either Fe or Zn deficiency. Additionally, the presence of specific cis-elements within their promoter regions, such as the E-box associated with Fe deficiency response and the ZDRE box linked to Zn deficiency response, was identified. This study lays a foundational groundwork for future research into the biological functions of NtZIP genes in tobacco in micronutrient regulation and homeostasis.

Comparative impact of seed priming with zinc oxide nanoparticles and zinc sulphate on biocompatibility, zinc uptake, germination, seedling vitality, and antioxidant modulation in groundnut

Comparative impact of seed priming with zinc oxide nanoparticles and zinc sulphate on biocompatibility, zinc uptake, germination, seedling vitality, and antioxidant modulation in groundnut

Exploring the uncharted: Zinc and phosphate solubilization in Zn-P isolates from wheat rhizosphere inceptisols

This research delves into the untapped potential of phosphorous and zinc solubilizing rhizobacteria, known as Zn-P isolates, from wheat rhizosphere inceptisols. A total of thirty rhizosphere soil samples were collected, resulting in recovery of forty unique bacterial isolates. After initial screening, out of forty isolates, recovered on the basis of halozone formation on the nutrient agar medium. four were subjected to biochemical and further molecular identification. Four isolates, identified as Bacillus subtilis (Zn-P-1), Pseudomonas aureginosa (Zn-P-2), Staphylococcus aureus (Zn-P-3), and Methylobacterium organophyllum (Zn-P-4) through a set of 16S rRNA primers, forward (5́- GGATGAGCCCGCGGCCTA-3́) and reverse (5́- CGGTGTGTACAAGGCCCGG-3́), exhibited superior solubilization efficiency of phosphorous and zinc These strains were evaluated via in vitro and pot culture assays. The study found that Zn-P-1 demonstrated the highest zinc solubilization (134.87 mg/l) when ZnO was used as the zinc source as compared to ZnCO3 and Zn-EDTA as also highest at 72.32 mg/l in CaH2PO4 and lowest at 14.44 mg/l with KH2PO4 using P sources, thus highlighting the role of Bacillus in zinc and phosphorous activity with substrate type. The inoculation of tri-calcium phosphate (TCP) and ZnCO3, along with Bacillus and Methylobacterium, led to increased phosphorous and zinc solubilization, uptake, and use efficiency, marking these rhizobacteria as potentially beneficial for nutrient enhancement and PGPR activities in wheat crops grown in inceptisols.

Green synthesis of zinc oxide nanoparticles for the industrial biofortification of (Pleurotus pulmonarius) mushrooms

Zinc malnutrition is major health problem in children and women of reproductive age (WRA) in developing countries. This study aimed to find nutritionally balanced food at an affordable cost. For this purpose, Pleurotus pulmonarius (Mushroom) is fortified with zinc oxide nano particles (ZnO-NPs) synthesized from Nigella sativa seed extract. ZnO-NPs were characterized using UV visible and FTIR Spectroscopy, SEM-EDX, XRD, PSA and Zeta potentials. ZnO-NPs were sprayed in different concentrations on substrate used for the cultivation of P. pulmonarius. Cultivated mushroom fruiting bodies were dried and powdered. Bio absorption of zinc was calculated using atomic absorption spectroscopy. Zinc absorption increased by enhancing the number of nano particles spraying on lingo-cellulosic substrate. The controlled bag had 2.27 ± 0.00 mg of zinc content per 2 g of mushroom powder. The minimum amount (3.46 ± 0.16 mg/2 g of mushroom) of zinc micronutrient was absorbed by the bag having 50 mg spray of ZnO-NPs per Kg of the wheat straw. Maximum amount of bio accumulation was done by bag having 5000 mg spray of ZnO-NPs (10.46 ± 0.08 mg/2 g of mushrooms powder). Zinc fortification had a significant (p < 0.05) effect on the uptake of zinc by fruiting bodies. ZnO-NPs at the concentration of 200 mg per kilogram of substrate gave optimized value of biological efficiency [B.E] (40.2 % ± 0.25), while B.E decreased with the increase in ZnO-NPs spray due to bio accumulation of zinc with increased concentration of ZnO-NPs spray.

Estimation of Nutrient Uptake and Available Nutrient Status of Rabi Safflower Through Soil Test Crop Response in Rainfed Ecosystem

Background: Adoption of SSNM is directly affected by cost of fertilizer. Soil test crop response (STCR) concept attribute to contribution of soil and targeted yield level for fertilizer recommendation for a selected crop. This approach is also known as prescription based fertilizer recommendations. It is specific type of soil, climatic condition and specific location. Nutrient requirement is differ for different crops. The available soil nutrients efficient used and added to those available soil nutrients through fertilizers is different for different type of soil geography under a particular set of climatic conditions. Methods: A research experiment was carried out during rabi 2017-18, 2018-19 and 2019-20 at Research Farm of Agronomy, Dr. P.D.K.V, Akola (Maharashtra). Fertilizers were applied based on uptake pattern of crop, target yield levels and soil test values. The experiment was laid out in FRBD-Factorial randomized block design with two factors. Total 15 treatment combinations were formed which replication 4 times. Result: Significantly greater uptake of nitrogen (62.76, 74.67 and 81.89 kg ha-1), phosphorus (19.15, 24.32 and 29.38 kg ha-1), potassium (80.32, 92.14 and 99.18 kg ha-1), sulphur (18.46, 24.10 and 26.03 kg ha-1) and zinc (493.97, 571.01 and 620.91 g ha-1) recorded in treatment where crop supplied with farm yard manure @ 5 t ha-1 than rest of treatments during 2017-18, 2018-19 and 2019-20, respectively. A similar trend was observed in respect of soil nutrient status such as available N, P2O5, K2O, S and Zn. Application of fertilizers through soil test crop response equation with zinc sulphate @ 25 kg ha-1 and Sulphur @ 10 kg ha-1 registered maximum total uptake of nitrogen (66.89, 78.99 and 90.06 kg ha-1), phosphorus (20.78, 25.31 and 31.96 kg ha-1), potassium (86.05, 97.99 and 109.09 kg ha-1), sulphur (20.27, 26.39 and 29.80 kg ha-1) and zinc (537.78, 618.06 and 696.21 g ha-1) than rest of nutrient management treatments during three years of field experiment, respectively. The same trend was observed with respect to available N, P2O5, K2O, S and Zn under respective treatment during three years of experimentation.

Absorption of commercial and nanoparticulate ZnO and MgO synthesized by combustion reaction applied to maize soil

Nanotechnology has rapidly expanded across various fields, yet its application in agriculture remains underexplored. This study investigates the impact of zinc oxide (ZnO) and magnesium oxide (MgO) nanoparticles on maize cultivation, comparing commercial samples with those synthesized by combustion reaction. Synthesized ZnO and ZnO/MgO (1:1 by mass) were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM) to determine particle size and morphology. The experimental design assessed the effects of different treatments on magnesium and zinc uptake in maize roots and leaves, using atomic absorption spectrometry (AAS) for analysis. Results indicate that commercial ZnO significantly increased Zn absorption compared to synthesized samples and the control group, highlighting the influence of particle size and surface area on nutrient uptake. This study provides valuable insights into the potential of nanomaterials into the plant’s absorption mechanism as well as show that the availability of Zn NP synthesized contributes to the absorption of zinc by the plant without competing with Mg. On the other hand, when in Zn commercial, Mg absorption may be impaired.

Zinc/Iron-Regulated Transporter-like Protein CsZIP4 Enhances Zinc and Nitrogen Uptake and Alleviates Zinc Stresses with Nitrogen Supply in Camellia sinensis.

Zinc (Zn) and nitrogen (N) are the two crucial nutrients for tea plant growth and development and contribute to the quality formation of tea fresh leaves. In this study, a zinc/iron-regulated transporter-like protein 4 gene (i.e., CsZIP4) was functionally characterized. Expression profiling showed that CsZIP4 could be induced by Zn stresses and a N deficiency. Heterologous expression of CsZIP4 in yeast revealed that CsZIP4 possessed the capacity for Zn transport but not ammonium. Moreover, CsZIP4 overexpression in Arabidopsis thaliana promoted Zn and N uptake and transport and contributed to alleviate Zn stresses by collaborating with N supply, which might be interrelated to the expression of N or Zn metabolism-related genes, such as AtNRT1.1 and AtZIP4. Additionally, CsZIP4 was localized in the plasma membrane and chloroplast, which was helpful in maintaining cellular homeostasis under a Zn excess. Furthermore, silencing of CsZIP4 in tea plants by virus-induced gene silencing increased the chlorophyll content but decreased the Zn content. Finally, the yeast one-hybrid assay demonstrated that CsbZIP2 bound to the CsZIP4 promoter. These results will shed light on the functions of CsZIP4 in the N and Zn interaction in tea plants.

Effect of Chinese Milk Vetch on Zinc Content and Zinc Absorption of Rice in Purple Tidal Mud Soil

Rice is a staple food crop that feeds billions globally. Addressing Zn deficiency in rice is crucial for improving nutrition and food security. Zn deficiency in rice is a widespread issue, especially in purple tidal mud substrates, which often exhibit low Zn availability. The objective of this two-year pot study was to explore the relationship between Zn content, yield components, and Zn absorption in rice grown in purple tidal mud substrate with varying amounts of Chinese milk vetch (Astragalus sinicus L.) incorporation. The experimental design consisted of seven treatments: an unfertilized control, a Chinese milk vetch control, a chemical fertilizer control, and four treatment variations incorporating Chinese milk vetch alongside chemical fertilizer applications. The results indicated that planting and applying Chinese milk vetch improved the grain yield of rice in purple tidal mud substrate, and the yield increased with higher levels of Chinese milk vetch applied. The increased grain yield resulted in higher Zn absorption in rice grains. The application of Chinese milk vetch, both solely and in combination with chemical fertilizers, had varying effects on zinc uptake and grain zinc formation efficiency in early and late rice, with the control and low-level Chinese milk vetch treatments generally exhibiting the highest performance across the two-year period. By introducing Chinese milkvetch following the use of chemical fertilizers, the Zn content in rice grains increased starting from the second year. The treatment with Chinese milkvetch applied at a rate of 2.25 t/hm2 showed the best results in increasing the Zn content in rice grains. The increase in Zn content and Zn uptake by the rice plants gave rise to a lowering of the DTPA-extractable Zn content in the purple tidal mud substrate. Sole Chinese milk vetch application and using Chinese milk vetch following chemical fertilizer application both increased Zn content extracted by DTPA in purple tidal mud substrate.

Fluorescent protein-based Zn2+ sensors reveal distinct responses of aerobic and anaerobic Escherichia coli cultures to excess Zn2+

Zinc ions are required by all known organisms. Maintaining zinc homeostasis by preventing toxic overload while ensuring sufficient acquisition for cellular functions is crucial for survival and growth of bacteria. Bacteria, however, frequently encounter and must survive in various environments. During infection in host animals, for example, bacteria are exposed to acidic conditions in the stomach and anaerobic conditions in the intestines, but the effects of oxygen on zinc homeostasis in E. coli have not been well-studied. Previously, we reported a flavin-binding fluorescent protein-based zinc sensor, CreiLOVN41C, which can respond to changes in labile Zn2+ levels in bacteria under both aerobic and anaerobic conditions. Here, we combined the use of CreiLOVN41C with established oxygen-dependent fluorescent protein-based sensors, inductively coupled plasma-mass spectrometry (ICP-MS), and growth curves to evaluate how oxygen levels affect zinc uptake in E. coli. ICP-MS results showed that cells grown aerobically with added zinc acquired more zinc, but no additional zinc was accumulated when cells were grown anaerobically. Using oxygen-independent CreiLOVN41C and the oxygen-dependent ZapCY series of sensors, intracellular labile zinc was detected in E. coli grown with varied zinc under varied conditions. Although little to no endogenous zinc was detected by any sensor in E. coli cells grown with up to 2 mM added zinc, CreiLOVN41C revealed that when Zn2+ was added and detected by cells in real-time, anaerobic cells required more Zn2+ to similarly saturate the sensor. Overall, this work reveals that zinc uptake in E. coli is impacted by oxygen levels during cell growth.

Contribution of plant growth-promoting endophytic bacteria from hyperaccumulator to non-host plant zinc nutrition and health

Application of microbial agents is a novel strategy to improve the quality and health of plant, which can be used to increase zinc (Zn) uptake and alleviate Zn toxicity. Here, endophytic bacteria with Zn solubilizing and growth-promoting properties were isolated from hyperaccumulating ecotype (HE) of Sedum alfredii Hance and their effects on Zn absorption and accumulation of non-hyperaccumulating ecotype (NHE) were studied. The results showed that most endophytic bacteria of HE have good Zn solubilizing or growth-promoting properties. Under the condition of 20 μM ZnSO4, the biomass of NHE inoculated with SaPS1, SaEN2, SaPR2, SaBA2, SaBA3 was 2.8–3.2 times higher than that of non-inoculation control, and the Zn concentration of shoots was increased by 45.9, 89.0, 53.7, 77.5, and 42.6% after inoculation with SaPA1, SaP1, SaEN2, SaBA1, and SaBA2. Under the condition of 100 μM ZnSO4, inoculation with SaVA1, SaPS3, SaB1, SaPR1, and SaEN3 alleviated Zn stress and significantly reduced Zn concentration of shoots. Therefore, endophytic bacteria can be an effective means of improving plant Zn nutrition quality in the normal condition and benefit plant health in the stress environment.

Precise partial root-zone irrigation technique and potassium-zinc fertigation management improve maize physio-biochemical responses, yield, and water use in arid climate

BackgroundTo optimize irrigation water use and productivity, understanding the interactions between plants, irrigation techniques, and fertilization practices is crucial. Therefore, the experiment aims to assess the effectiveness of two application methods of potassium humate combined with chelated zinc under partial root-zone drip irrigation techniques on maize nutrient uptake, yield, and irrigation water use efficiency across two irrigation levels.MethodsOpen-field experiments were carried out in two summer seasons of 2021 and 2022 under alternate and fixed partial root-zone drip irrigation techniques to investigate their impacts at two irrigation levels and applied foliar and soil applications of potassium humate or chelated zinc in a sole and combinations on maize.ResultsDeficit irrigation significantly increased hydrogen peroxide levels and decreased proline, antioxidant enzymes, carbohydrate, chlorophyll (a + b), and nutrient uptake in both partial root-zone techniques. The implementation of combined soil application of potassium humate and chelated zinc under drought conditions on maize led to varying impacts on antioxidant enzymes and nutritional status, depending on the type of partial root-zone technique. Meanwhile, the results showed that fixed partial root-zone irrigation diminished the negative effects of drought stress by enhancing phosphorus uptake (53.8%), potassium uptake (59.2%), proline (74.4%) and catalase (75%); compared to the control. These enhancements may contribute to improving the defense system of maize plants in such conditions. On the other hand, the same previous treatments under alternate partial root zone modified the defense mechanism of plants and improved the contents of peroxidase, superoxide dismutase, and the uptake of magnesium, zinc, and iron by 81.3%, 82.3%, 85.1%, 56.9%, and 80.2%, respectively.ConclusionsAdopting 75% of the irrigation requirements and treating maize plants with the soil application of 3 g l−1 potassium humate combined with 1.25 kg ha−1 chelated zinc under alternate partial root-zone technique, resulted in the maximum root length, leaf water content, chlorophyll content, yield, and irrigation water use efficiency.

Effect of Zinc Application on Growth, Yield, Zinc uptake and Zinc Use Indices of Rice

A field experiment was conducted at the agriculture farm, Palli Siksha Bhavana, Visva-Bharati, Birbhum, West Bengal, India during kharif (rainy) seasons (June–September) of 2016 and 2017 to study effect of zinc application on growth, yield and nutrient uptake of rice. The experiment was laid out in split plot design replicated thrice, consisting two main plot treatments i.e. crop establishment methods (CEMs) and seven sub-plot treatments (levels of zinc and methods of application). Two CEMs were direct seeded rice (DSR) and transplanted puddled rice (TPR) and seven levels of zinc and methods of application were namely control (Zn0), Seed coating of Zn @ 1250 mg kg-1 (Zn1), Seed coating of Zn @ 2500 mg kg-1 (Zn2), Seed coating of Zn @ 3750 mg kg-1 (Zn3), two foliar sprays @ 1050 mg kg-1 (Zn4), three foliar spray @ 1050 mg kg-1 (Zn5), 2500 mg kg-1 seed coating+2-foliar spray @ 1050 mg kg-1 (Zn6). In respect of yield attribute and yield, Zn6 resulted significantly highest number of Panicle m-2 as well as number of filled grains panicle-1. Zn3 though recorded 5.7% more grain yield than Zn6 but later Zn6 resulted highest zinc concentration and uptake. Zn1 recorded highest zinc use indices. Zn1 resulted much highest Zn use efficiency than foliar application and combined application of seed coating and foliar spray. Correlation between Zn levels and Zn concentration in both grain and straw of rice was highly positive; very highly positive correlation was recorded with the Zn levels and Zn uptake by both grain and straw.