Mn Deficiency Research Articles

Ca2+-dependent phosphorylation of NRAMP1 by CPK21 and CPK23 facilitates manganese uptake and homeostasis in Arabidopsis

Homeostasis of the essential micronutrient manganese (Mn) is crucially determined through availability and uptake efficiency in all organisms. Mn deficiency of plants especially occurs in alkaline and calcareous soils, seriously restricting crop yield. However, the mechanisms underlying the sensing and signaling of Mn availability and conferring regulation of Mn uptake await elucidation. Here, we uncover that Mn depletion triggers spatiotemporally defined long-lasting Ca2+ oscillations in Arabidopsis roots. These Ca2+ signals initiate in individual cells, expand, and intensify intercellularly to transform into higher-order multicellular oscillations. Furthermore, through an interaction screen we identified the Ca2+-dependent protein kinases CPK21 and CPK23 as Ca2+ signal-decoding components that bring about translation of these signals into regulation of uptake activity of the high-affinity Mn transporter natural resistance associated macrophage proteins 1 (NRAMP1). Accordingly, a cpk21/23 double mutant displays impaired growth and root development under Mn-limiting conditions, while kinase overexpression confers enhanced tolerance to low Mn supply to plants. In addition, we define Thr498 phosphorylation within NRAMP1 as a pivot mechanistically determining NRAMP1 activity, as revealed by biochemical assays and complementation of yeast Mn uptake and Arabidopsis nramp1 mutants. Collectively, these findings delineate the Ca2+-CPK21/23-NRAMP1 axis as key for mounting plant Mn homeostasis.

Tonoplast-localized transporter ZmNRAMP2 confers root-to-shoot translocation of manganese in maize.

Almost all living organisms require manganese (Mn) as an essential trace element for survival. To maintain an irreplaceable role in the oxygen-evolving complex of photosynthesis, plants require efficient Mn uptake in roots and delivery to above-ground tissues. However, the underlying mechanisms of root-to-shoot Mn translocation remain unclear. Here, we identified an Natural Resistance Associated Macrophage Protein (NRAMP) family member in maize (Zea mays), ZmNRAMP2, which localized to the tonoplast in maize protoplasts and mediated transport of Mn in yeast (Saccharomyces cerevisiae). Under Mn deficiency, two maize mutants defective in ZmNRAMP2 exhibited remarkable reduction of root-to-shoot Mn translocation along with lower shoot Mn contents, resulting in substantial decreases in Fv/Fm and plant growth inhibition compared to their corresponding wild-type (WT) plants. ZmNRAMP2 transcripts were highly expressed in xylem parenchyma cells of the root stele. Compared to the WT, the zmnramp2-1 mutant displayed lower Mn concentration in xylem sap accompanied with retention of Mn in root stele. Furthermore, the overexpression of ZmNRAMP2 in transgenic maize showed enhanced root-to-shoot translocation of Mn and improved tolerance to Mn deficiency. Taken together, our study reveals a crucial role of ZmNRAMP2 in root-to-shoot translocation of Mn via accelerating vacuolar Mn release in xylem parenchyma cells for adaption of maize plants to low Mn stress and provides a promising transgenic approach to develop low Mn-tolerant crop cultivars.

Ru-Doping of P2-NaxMn0.75Ni0.25O2-Layered Oxides for High-Energy Na-Ion Battery Cathodes: First-Principles Insights on Activation and Control of Reversible Oxide Redox Chemistry

Design and development of high-energy, efficient, and structurally stable positive electrodes for Na-ion batteries (NIBs) have recently been focusing on layered transition metal oxides (NaxTMO2, 0 < x < 1). When doped with late transition metals, the redox reactions ensuring the charge compensation upon Na+ removal can rely on the direct participation of anionic chemistry, with encouraging outcomes in terms of both energy density and power. However, the control of reversible O2–/O– reactions is still a major issue, as the undesired release of O2 can lead to detrimental effects on cathode capacity and overall cell stability. The fine-tuning of metal–oxygen bond covalency has recently emerged as a promising strategy toward the reversible access of oxygen redox. Following the route paved by Ru-based Li-rich cathode materials, we hereby present a first-principles investigation of a Ru-doped NaxTMO2 (TM = Ru, Ni, and Mn) system and the related structural and electronic properties of interest for NIB applications. We aim to dissect the specific role of each element sublattice in compensating the electronic charge along desodiation, with a major focus on the anionic contribution. The oxygen activity is addressed in the high-voltage range (i.e.,xNa = 0.25), and the underlying mechanism is derived from PBE + U(-D3BJ) calculations. We also discuss the effects of Mn deficiency as a suitable site for the formation of low-energy superoxide species via preferential breaking of the Ni–O bond. Conversely, breaking a Ru–O bond is unlikely to occur, which assesses the key role of the Ru dopant in stabilizing the oxide lattice and enabling the desired reversible conditions. Our results also highlight the oxygen vacancy formation energy as an effective descriptor for different activities toward the O2–/O–/O2 evolution. All these theoretical insights can be useful to drive further experimental efforts toward the optimal design of efficient and high-energy NIB cathodes with enhanced practical reversible capacity.

Interaction of silicon and manganese in nutritional and physiological aspects of energy cane with high fiber content

BackgroundSilicon (Si) is a multiple stress attenuator element in plants, however more research is needed to elucidate the actions in the plants defense system with low nutrition of manganese (Mn) for a prolonged period, and the attenuation mechanisms involved in the effects of Mn deficiency on energy cane with high fiber content. Thus, the objective of this study was to evaluate whether Si reduces the oxidative stress of the energy cane grown in low Mn in nutrient solution, to mitigate the effects of Mn deficiency, improving enzymatic and non-enzymatic defense, uptake of Mn the plant growth.MethodsAn experiment was carried out with pre-sprouted seedlings of Saccharum spontaneum L. in a 2 × 2 factorial scheme in five replications in which the plants were grown under sufficiency (20.5 μmol L−1) and deficiency (0.1 μmol L−1) of Mn combined with the absence and presence of Si (2.0 mmol L−1) for 160 days from the application of the treatments. The following parameters were evaluated: accumulation of Mn and Si, H2O2, MDA, activity of SOD and GPOX, total phenol content, pigments, and quantum efficiency of PSII.ResultsMn deficiency induced the oxidative stress for increase the H2O2 and MDA content in leaves of plants and reduce the activity of antioxidant enzymes and total phenols causing damage to quantum efficiency of photosystem II and pigment content. Si attenuated the effects of Mn deficiency even for a longer period of stress by reducing H2O2 (18%) and MDA (32%) content, and increased the Mn uptake efficiency (53%), SOD activity (23%), GPOX (76%), phenol contents, thus improving growth.ConclusionsThe supply of Si promoted great nutritional and physiological improvements in energy cane with high fiber content in Mn deficiency. The results of this study propose the supply of Si via fertirrigation as a new sustainable strategy for energy cane cultivation in low Mn environments.

HIF-1α upregulation exerts the antagonistic effect against angiogenesis inhibition in manganese deficiency-induced tibial dyschondroplasia of broiler chicks.

Manganese (Mn) is an essential microelement for broiler breeding and its deficiency causes tibial dyschondroplasia (TD). Tibial growth plate (TGP) development and metaphyseal vascularization are crucial for tibia growth in fast-growing broiler chickens, but their roles in Mn deficiency-induced TD in chicks remain unclear. This study was designed to clarify this issue. A total of 36 one-day-old broilers were divided into the control group and Mn-deficiency (Mn-D) group, which were fed with a standard diet (60mg Mn/kg) and Mn deficiency diet (22mg Mn/kg) for 42 days, respectively. TGP and proximal tibial metaphysis were collected to perform the related assays. This study found that Mn deficiency decreased the tibia length and TGP thickness in the TD model. Also, Mn deficiency increased the irregular and white tibial dyschondroplasia lesions (TDL) region under the TGP, and reduced the expression levels of vascular endothelial growth factor (VEGF) and macrophage migration inhibitory factor (MIF). Combined with histological assessment, it was suggested that Manganese deficiency inhibited angiogenesis in the proximal tibial metaphysis. Meanwhile, Mn deficiency enhanced the expression levels of hypoxia-inducible factor-1 α (HIF-1α), autophagy-related protein 5 (ATG5), and microtubule-associated protein 1 light chain 3 β (LC3-II) in TGP, but decreased the expression level of SQSTM1 (P62), which suggested that autophagy was activated during this process. Collectively, these data indicate that HIF-1α up-regulation and concurrent autophagy activation exert a protective effect against Mn deficiency-induced angiogenesis inhibition, which may provide useful guidance to prevent TD in broilers.

A Metal Chaperone Gene Regulates Rice Growth and Seed Development by Manganese Acquisition and Homeostasis

Manganese (Mn) is a mineral element essential for plant growth and development. In agronomy reality, Mn deficiency or overload in crops disturbs metal homeostasis, photosynthesis, and many other biological processes. Mining genetic resources linking Mn acquisition and homeostasis is vitally important to help understand plant adaptation to Mn stress and breeding genetically improved crops for sustainable agriculture. Metallic chaperone (metallochaperone) is a class of family proteins playing an essential role in positive responses to metal and abiotic stresses. Here, we report a novel function of a metal chaperone gene OsHIPP56 in regulating Mn accumulation in rice (Oryza sativa) crops. OsHIPP56 was transcriptionally induced by excessive Mn stress but hardly by Mn deficiency. OsHIPP56-expression in a yeast Mn-sensitive mutant pmr1 rescued the Mn-defective phenotype by increasing Mn accumulation in cells. Knocking out OsHIPP56 by Crispr/cas9 protocol did not affect the growth and physiological responses of rice seedlings supplied with normal Mn concentration. However, excess Mn stress moderately retarded growth of the knockout plants compared with the wild-type. A life span field trial was conducted under natural conditions with the two rice varieties. Knocking out OsHIPP56 also distorted rice growth, leading to reduced plant height, stem elongation, panicle length, spikelet fertility, seed size, and grain yield. Mn concentrations in rice straw (leaves and stem/internodes), brown rice, and husk in cas9 plants were much lower than those in wild-type. This was particularly seen in the brown rice where the Mn concentrations in cas9 plants were reduced by 26.7–49.1% compared with the wild-type control. Overall, these lines of evidence point out that OsHIPP56 plays a primary role required for rice growth, seed development, and Mn acquisition.

Quantitative Trait Locus Mapping of Marsh Spot Disease Resistance in Cranberry Common Bean (Phaseolus vulgaris L.).

Common bean (Phaseolus vulgaris L.) is a food crop that is an important source of dietary proteins and carbohydrates. Marsh spot is a physiological disorder that diminishes seed quality in beans. Prior research suggested that this disease is likely caused by manganese (Mn) deficiency during seed development and that marsh spot resistance is controlled by at least four genes. In this study, genetic mapping was performed to identify quantitative trait loci (QTL) and the potential candidate genes associated with marsh spot resistance. All 138 recombinant inbred lines (RILs) from a bi-parental population were evaluated for marsh spot resistance during five years from 2015 to 2019 in sandy and heavy clay soils in Morden, Manitoba, Canada. The RILs were sequenced using a genotyping by sequencing approach. A total of 52,676 single nucleotide polymorphisms (SNPs) were identified and filtered to generate a high-quality set of 2066 SNPs for QTL mapping. A genetic map based on 1273 SNP markers distributed on 11 chromosomes and covering 1599 cm was constructed. A total of 12 stable and 4 environment-specific QTL were identified using additive effect models, and an additional two epistatic QTL interacting with two of the 16 QTL were identified using an epistasis model. Genome-wide scans of the candidate genes identified 13 metal transport-related candidate genes co-locating within six QTL regions. In particular, two QTL (QTL.3.1 and QTL.3.2) with the highest R2 values (21.8% and 24.5%, respectively) harbored several metal transport genes Phvul.003G086300, Phvul.003G092500, Phvul.003G104900, Phvul.003G099700, and Phvul.003G108900 in a large genomic region of 16.8–27.5 Mb on chromosome 3. These results advance the current understanding of the genetic mechanisms of marsh spot resistance in cranberry common bean and provide new genomic resources for use in genomics-assisted breeding and for candidate gene isolation and functional characterization.

A weak allele of OsNRAMP5 confers moderate cadmium uptake while avoiding manganese deficiency in rice.

Decreasing cadmium (Cd) concentrations in rice grains can effectively reduce potential risks to human health because rice is the major contributor to Cd intake in many diets. Among several genes involved in rice Cd accumulation, the loss of function of OsNRAMP5 is known to be effective in reducing grain concentration by inhibiting root uptake. However, disruption of this gene simultaneously decreases manganese (Mn) uptake because OsNRAMP5 is a major Mn transporter. With the aim of improving Mn uptake in OsNRAMP5 mutants while still restricting the grain Cd concentration below the upper limit of international standards, we identified a novel OsNRAMP5 allele encoding a protein in which glutamine (Q) at position 337 was replaced by lysine (K). The mutant carrying the OsNRAMP5-Q337K allele showed intermediate Cd and Mn accumulation between that of the wild-type and OsNRAMP5-knockout lines, and exhibited more resistance to Mn deficiency than the knockout lines. Different amino acid substitutions at position Q337 significantly affected the Cd and Mn transport activity in yeast cells, indicating that it is one of the crucial sites for OsNRAMP5 function. Our results suggest that the OsNRAMP5-Q337K allele might be useful for reducing grain Cd concentrations without causing severe Mn deficiency in rice cultivars through DNA marker-assisted breeding.

Crystal growth and magnetic properties of LaMn0.91Sb2 and NdMn0.88Sb2

In this work, single crystals of ${\mathrm{LaMn}}_{0.91}{\mathrm{Sb}}_{2}$ and ${\mathrm{NdMn}}_{0.88}{\mathrm{Sb}}_{2}$ with deficiencies of Mn have been successively grown by using the Bi-flux method. They all crystallize in the ${\mathrm{HfCuSi}}_{2}$-type tetragonal structure with space group $P4$/nmm (No.129). ${\mathrm{LaMn}}_{0.91}{\mathrm{Sb}}_{2}$ displays signs of successive antiferromagnetic transitions around 133 and 108 K for $H||c$. In the case of $H\ensuremath{\perp}c$, ${\mathrm{LaMn}}_{0.91}{\mathrm{Sb}}_{2}$ shows signs of weak ferromagnetic transition around 138 K and antiferromagnetic transition at 56 K. However, there is no anomaly observed in the temperature-dependent specific heat curve. For ${\mathrm{NdMn}}_{0.88}{\mathrm{Sb}}_{2}$ measured with $H||c$, the Mn sublattice orders antiferromagnetically below 170 K and the Nd sublattice shows successive antiferromagnetic orders at 34 and 26 K. The antiferromagnetic state of Nd sublattice can be induced to be a ferromagnetic state through a spin-flop transition at 2 K. When $H\ensuremath{\perp}\mathrm{c}$, the Mn sublattice displays antiferromagnetic orders at 171, 156, and 74 K. The Nd sublattice orders antiferromagnetically below 32 K. Ferromagnetic state for the Nd sublattice is induced by magnetic fields through a spin-flop transition at 2 K. Magnetic phase diagrams for ${\mathrm{NdMn}}_{0.88}{\mathrm{Sb}}_{2}$ are depicted for cases of $H||c$ and $H\ensuremath{\perp}c$, respectively. ${\mathrm{LaMn}}_{0.91}{\mathrm{Sb}}_{2}$ and ${\mathrm{NdMn}}_{0.88}{\mathrm{Sb}}_{2}$ show metallic behavior. Negative magnetoresistance in ${\mathrm{LaMn}}_{0.91}{\mathrm{Sb}}_{2}$ and ${\mathrm{NdMn}}_{0.88}{\mathrm{Sb}}_{2}$ are possibly related to canted-antiferromagnetic orders of Mn sublattices.

OsZIP11 is a trans-Golgi-residing transporter required for rice iron accumulation and development

Iron (Fe) is a mineral nutrient necessary for plant growth and development. Whether the rice ZRT/IRT-like protein family metal transporter OsZIP11 is involved in Fe transport has not been functionally defined. The objective of the study is to figure out the essential role of the uncharacterized OsZIP11 played in rice growth, development, and iron accumulation, particularly in seeds. Transient subcellular location assays show that OsZIP11 was targeted to the trans-Golgi network. OsZIP11 was preferentially expressed in the rice tissues (or organs) at later flowering and seed development stages. Transcripts of OsZIP11 were significantly induced under Fe but not under zinc (Zn), copper (Cu) or manganese (Mn) deficiency. Yeast (Saccharomyces cerevisiae) transformed with OsZIP11 sequences displayed an active iron input which turned out that excessive iron accumulated in the cells. Knocking out OsZIP11 by CRISPR-Cas9 approach led to the attenuated rice growth and physiological phenotypes, depicting shorter plant height, reduced biomass, chlorosis (a symptom of lower chlorophyll concentration), and over-accumulation of malondialdehyde (complex representing the peroxidation of membrane lipids) in rice plantlets. The field trials demonstrated that OsZIP11 mutation impaired the capacity of seed development, with shortened panicle and seed length, compromised spikelet fertility, and reduced grain per plant or 1000-grain weight. Knocking out OsZIP11 also lowered the accumulation of iron in the brown rice by 48–51% compared to the wild-type. Our work pointed out that OsZIP11 is required for iron acquisition for rice growth and development.

Characterization of the NRAMP Gene Family in the Arbuscular Mycorrhizal Fungus Rhizophagus irregularis.

Transporters of the NRAMP family are ubiquitous metal-transition transporters, playing a key role in metal homeostasis, especially in Mn and Fe homeostasis. In this work, we report the characterization of the NRAMP family members (RiSMF1, RiSMF2, RiSMF3.1 and RiSMF3.2) of the arbuscular mycorrhizal (AM) fungus Rhizophagus irregularis. Phylogenetic analysis of the NRAMP sequences of different AM fungi showed that they are classified in two groups, which probably diverged early in their evolution. Functional analyses in yeast revealed that RiSMF3.2 encodes a protein mediating Mn and Fe transport from the environment. Gene-expression analyses by RT-qPCR showed that the RiSMF genes are differentially expressed in the extraradical (ERM) and intraradical (IRM) mycelium and differentially regulated by Mn and Fe availability. Mn starvation decreased RiSMF1 transcript levels in the ERM but increased RiSMF3.1 expression in the IRM. In the ERM, RiSMF1 expression was up-regulated by Fe deficiency, suggesting a role for its encoded protein in Fe-deficiency alleviation. Expression of RiSMF3.2 in the ERM was up-regulated at the early stages of Fe toxicity but down-regulated at later stages. These data suggest a role for RiSMF3.2 not only in Fe transport but also as a sensor of high external-Fe concentrations. Both Mn- and Fe-deficient conditions affected ERM development. While Mn deficiency increased hyphal length, Fe deficiency reduced sporulation.

Sustainable Upcycling of Spent Lithium‐Ion Batteries Cathode Materials: Stabilization by In Situ Li/Mn Disorder

AbstractThe non‐destructive repair of spent lithium‐ion batteries cathode materials has been the holy grail in the field of waste‐to‐resource research due to the potential for optimal environmental and economic benefits. Here, Mn deficiency and cationic disorder in degraded materials are discovered for the first time and the degraded crystal structure is repaired by the in situ upcycling process using a low‐carbon and economical technique. The repaired disordered LiMn2O4 (LMO) material can contribute higher capacity and greater stability than ordered LMO materials. This unexpected behavior is attributed to the in‐situ upcycling process that enhances the Li/Mn atomic disorder, thereby altering the electrochemical activity as well as the structural stability of the cathode material. Specifically, the Li/Mn disorder can effectively suppress the Jahn–Teller distortion and two‐phase phase transition and activate the activity of disordered Li, contributing to a stable high discharge capacity of upcycled material. The discovery of the Mn‐deficiency mechanism solves many doubts as to the conventional repair technology and can provide a more adequate theoretical guidance of the development of recycling technology together with the Li‐deficiency mechanism. The atomic disorder structure also provides guidance for the design of battery materials and promotes the sustainable development of future green lithium‐ion batteries.

Ulva prolifera Polysaccharide-Manganese Alleviates Inflammation and Regulates Microbiota Composition in Dextran Sulfate Sodium-Induced Colitis Mice.

Manganese (Mn) deficiency exacerbates colitis symptoms, whereas diet supplemented with inorganic Mn merely maintains colon length in experimental colitis. In the present study, a new form of Mn, Ulva prolifera polysaccharide cheated-Mn (PMn) was used and its treatment effects on dextran sulfate sodium (DSS)-induced colitis were investigated. Male C57BL/6 mice were orally administrated with 3.5% DSS to induce colitis. Then, the colitis mice were treated with PBS or PMn for 7 days. The results showed that PMn administration help retrieve the body weight loss and intestinal morphology damage, and alleviate apoptosis and inflammatory responses in colitis mice. Moreover, PMn administration decreased intestinal infiltration as indicated by decreased concentration of myeloperoxidase and eosinophil peroxidase. Importantly, PMn retrieved the increased abundance of Firmicutes and the decreased abundance of Bacteroidetes caused by DSS, suggested its beneficial roles in regulating microbiota composition in mice with colon inflammation. Gut microbiota composition at the genus level in the mice administrated with PMn was similar to those in control mice, whereas they were clearly distinct from DSS-treated mice. These results support the potential therapeutic role of PMn in the treatment of intestinal colitis and microbes may play critical roles in mediating its effects.

Using EfficientNet and transfer learning for image-based diagnosis of nutrient deficiencies

Early diagnosis of nutrient deficiencies can play a major role in avoiding significant agricultural losses and increasing the final yield while preserving the environment through efficient fertilizer usage. In this work, we study how well nutrient deficiency symptoms can be recognized in RGB images by using deep neural networks and transfer learning. Two different datasets, presenting real-world conditions, were used for this purpose. The first one was the Deep Nutrient Deficiency for Sugar Beet (DND-SB) dataset, which contains 5648 images of sugar beets presenting nitrogen (N), phosphorous (P), and potassium (K) deficiencies, the omission of liming (Ca) and full fertilization. The second one, collected on the field for this research and currently publicly available, was a dataset combining different orange tree images with iron (Fe), potasssium (K), magnesium (Mg), and manganese (Mn) deficiencies. Image classification via fine-tuning with EfficientNetB4, whose original weights came from a noisy student training on ImageNet, obtained the best performances on both datasets with 98.65% and 98.52% Top-1 accuracies. Additionally, the Grad-CAM++ analysis showed that the models were performing an accurate analysis of the most relevant part inside the images. Finally, the use of agricultural transfer learning did not report improvement in the performances.

First‐principles insights on anion redox activity in NaxFe1/8Ni1/8Mn3/4O2: Toward efficient high‐energy cathodes for Na‐ion batteries

AbstractIn the search for high‐energy cathode materials for Na‐ion batteries (NIBs), Fe‐doped layered transition metal oxides have been recently proposed as promising systems that can ensure improved reversible capacity at high working voltage. Exploiting the anionic redox chemistry in this class of materials represents a great advance for the energy storage community, but uncontrolled oxidation process can lead to the formation of unbound molecular oxygen, with detrimental effects on overall capacity and stability upon cycling. The higher TM–O covalency provided by Fe doping seems to prevent oxygen loss and ensure full capacity recovery. Understanding anionic processes and the underlying mechanism with atomistic details can reinforce the experimental efforts and help to outline rational design strategies for novel high‐performing NIB cathodes. To this end, we present a state‐of‐the‐art first‐principles study on the P2‐type NaxTMO2 (TM = Fe, Ni, and Mn—NFNMO) oxide. We compare structural and electronic features of stoichiometric (NaxFe0.125Ni0.125Mn0.75O2) and Mn‐deficient (NaxFe0.125Ni0.125Mn0.68O2) NFNMO to identify and discuss the contribution of each element sublattice on charge compensation processes. Although Mn deficiency is predicted to increase the cathode working voltage, we find the charge compensation being mostly exerted by the Ni and Fe sublattices. Oxygen redox is unfold via the formation of superoxide species at low Na loads with a preferential breaking of more labile Ni–O bonds and binding to Fe atoms. Our calculations predict no release of molecular O2 upon desodiation, thus highlighting the key role of Fe dopant that provides a good TM–O bond strength, preventing oxygen loss while still enabling anionic redox reactions at high voltages with extra reversible capacity.

NRAMP6 and NRAMP1 cooperatively regulate root growth and manganese translocation under manganese deficiency in Arabidopsis.

The essential micronutrient manganese (Mn) in plants regulates multiple biological processes including photosynthesis and oxidative stress. Some Natural Resistance-Associated Macrophage Proteins (NRAMPs) have been reported to play critical roles in Mn uptake and reutilization in low Mn conditions. NRAMP6 was demonstrated to regulate cadmium tolerance and iron utilization in Arabidopsis. Nevertheless, it is unclear whether NRAMP6 plays a role in Mn nutrition. Here, we report that NRAMP6 cooperates with NRAMP1 in Mn utilization. Mutation of NRAMP6 in nramp1 but not in a wild-type background reduces root growth and Mn translocation from the roots to shoots under Mn deficient conditions. Grafting experiments revealed that NRAMP6 expression in both the roots and shoots is required for root growth and Mn translocation under Mn deficiency. We also showed that NRAMP1 could replace NRAMP6 to sustain root growth under Mn deficiency, but not vice versa. Mn deficiency does not affect the transcript level of NRAMP6, but is able to increase and decrease the protein accumulation of NRAMP6 in roots and shoots, respectively. Furthermore, NRAMP6 can be localized to both the plasma membrane and endomembranes including the endoplasmic reticulum, and Mn deficiency enhances the localization of NRAMP6 to the plasma membrane in Arabidopsis plants. NRAMP6 could rescue the defective growth of the yeast mutant Δsmf2, which is deficient in endomembrane Mn transport. Our results reveal the important role of NRAMP6 in Mn nutrition and in the long-distance signaling between the roots and shoots under Mn deficient conditions.

Effects of Fe and Mn Deficiencies on the Root Protein Profiles of Tomato (Solanum lycopersicum) Using Two-Dimensional Electrophoresis and Label-Free Shotgun Analyses.

Iron (Fe) and manganese (Mn) are two essential elements for plants that compete for the same uptake transporters and show conflicting interactions at the regulatory level. In order to understand the differential response to both metal deficiencies in plants, two proteomic techniques (two-dimensional gel electrophoresis and label-free shotgun) were used to study the proteome profiles of roots from tomato plants grown under Fe or Mn deficiency. A total of 119 proteins changing in relative abundance were confidently quantified and identified, including 35 and 91 in the cases of Fe deficiency and Mn deficiency, respectively, with 7 of them changing in both deficiencies. The identified proteins were categorized according to function, and GO-enrichment analysis was performed. Data showed that both deficiencies provoked a common and intense cell wall remodelling. However, the response observed for Fe and Mn deficiencies differed greatly in relation to oxidative stress, coumarin production, protein, nitrogen, and energy metabolism.

Phytic acid and its reduction in pulse matrix: Structure–function relationship owing to bioavailability enhancement of micronutrients

AbstractThe bioavailability of minerals and proteins in the pulse is endured due to the presence of antinutrient phytic acid. Phytic acid is a proton donor that produces hydrogen ions (H+) and “phytate” anion, which readily forms salts with available minerals and protein. These phytate complexes are not bioavailable to humans and led to several public health problems like anemia, skeletal abnormalities, osteoporosis, malabsorption, and kwashiorkor syndrome due to Fe, Mn, Ca, Zn, and protein deficiency. Thus, it is a severe concern to the vegetarian population who strongly rely upon pulses to fulfill their daily nutrition requirements. Improving the bioavailability of micronutrients in the pulse matrix requires reduction of phytic acid. A phytic acid reduction strategy should ensure its efficient reduction leading to enhanced micronutrient bioavailability. This article provides a throughout view of the available phytic acid reduction technologies conducted at the postharvest stages of pulse processing. The mechanism of phytic acid reduction during conventional (soaking, cooking, and germination) and novel processing (irradiation, ultrasound, and high pressure) regarding its degradation and interaction with other components has been explored here, providing insight into structure–function relationships. Further, an in‐depth analysis of the combined treatments offering better phytic acid reductions has been explained in the light of structural alteration of phytic acid to its lower inositol phosphates. The summarized data on prospects and drawbacks of different phytic acid reduction strategies would provide background information to explore the futuristic possibilities for efficient phytic acid reduction and micronutrient fortification.Practical ApplicationsThe presence of phytic acid in the pulse matrix restricts the micronutrient absorption by complexing with micronutrients leading to their ineffectiveness. The bottom‐line population of the income pyramid, who are unable to intake micronutrients from other sources, suffers from several public health problems related to nutrient or combined nutrient deficiencies. Therefore, the degradation of phytic acid in pulses is necessary. This article aims to provide a comprehensive overview and explanation of phytic acid degradation during various postharvest pulses processing. The chelation of micronutrients by phytate, structural alterations during processing, and structure–function correlation of pulse matrices have been comprehensively enlightened here. These insights will aid researchers in exploring the future potential for phytic acid reduction and help develop proper strategies for pulse fortification.

Improving Rabbiteye Blueberry Performance in a Calcareous Soil by Growing Plants in Pits Filled with Low-CaCO3 Growth Media

Calcareous soils are not suitable for blueberry cultivation. Our aim was to improve the performance of blueberry plants in calcareous soils by using pits filled with growth media in combination with high levels of RNH4+ (proportion of N-NH4+ among the total applied N). Rabbiteye blueberry (Vaccinium virgatum Ait. cv. Ochlockonee) plants were grown in pits filled with a tuff/peat mixture (TP), a sandy soil (S) or a calcareous (CC), in full factorial combination with three levels of RNH4+: 33%, 66% or 100%. The two higher RNH4+ treatments decreased the pH of the low-CaCO3 (S) and no-CaCO3 (TP) media to ≤6.0 over 250 days of fertilization, but did not affect the pH of the CC soil over 650 days. Plant performance was superior in the TP and S media, as compared to the CC soil. The type of growth medium was the dominant factor accounting for the improved plant performance. The plants were sensitive to Mn deficiency in leaves during the spring period. The current results suggest that growing blueberry in pits filled with good aeration and low pH buffering capacity medium in combination with a high level of RNH4+ is a positive approach for its cultivation in calcareous soils.

Biofortification of wheat with Mn through tank mixed formulations of MnSO4 7H2O and CO(NH2)2—a fast mode of Mn accumulation on light textured soils of Punjab, India

In the Indo-gangetic plains, the continuous cultivation of rice-wheat cropping system in light-textured soils has aggravated a manganese (Mn) deficiency. Wheat is sensitive to Mn availability in soil and its deficiency has become one of the major constraints in sustaining its productivity on soils cropped with rice. Thus, field experiments were conducted to evaluate the response of tank-mixed formulations of manganese sulfate (MnSO4·7H2O) and urea (CO(NH2)2) at critical growth stages. The experiment comprised of six different treatments of MnSO4·7H2O (0.5%) and tank-mixed formulation of MnSO4·7H2O (0.5%) and CO(NH2)2 (1%) sprayed 35, 50 and 70 days after sowing (DAS). The results revealed that for biofortification, tank mixed formulation of MnSO4·7H2O (0.5%) with and without CO (NH2)2 (1.0%) at different growth stages resulted in significantly higher yield and Mn accumulation over control. The protein content, micronutrient concentrations (Zn, Fe and Mn) and accumulation in wheat were highest in the treatment having tank-mixed formulation of MnSO4·7H2O and CO(NH2)2 at 35, 50 and 75 DAS stages. However, it was statistically at par with tank-mixed formulation of MnSO4·7H2O (0.5%) and CO(NH2)2 (1.0%) sprayed at 35 and 50 DAS. The net return and B:C ratio were maximum (Rs 75,671 ha−1 and 2.97) in the treatment having tank-mixed formulation of MnSO4·7H2O plus CO(NH2)2 applied at 35 and 50 DAS. The results of the study concluded that the tank-mixed formulation is the appropriate combination for higher accumulation of Mn in wheat grains through biofortification.