Translocation Of Manganese Research Articles

The dynamic response mechanism of crops to manganese uptake and transfer mediated by different intercropping crop attributes.

An issue of pressing concern is the manganese contamination in farmland soils adjacent to industrial areas. To address this, intercropping hyperaccumulator plants with crops emerges as a sustainable approach to ensuring food security. This study aims to investigate the influence of intercropping Sedum alfredii with maize or soybean on their growth and the dynamics of manganese accumulation through field experiments. The results showed that compared with monoculture, the Sedum alfredii-maize intercropping system exhibited a land equivalent ratio (LER) of 1.89, signifying a 71.13% augmentation in bioaccumulation amount (BCA). Additionally, it led to a significant reduction in manganese content in various organs, ranging from 17.05% to 25.50%. However, the Sedum alfredii-soybean intercropping system demonstrated a LER of 1.94, accompanied by a 66.11% increase in BCA, but did not significantly reduce the manganese content in the roots, stems, and pods of soybeans. Furthermore, manganese accumulation in maize and soybean grains was primarily attributed to the aboveground translocation of manganese. The intercropping effect on blocking manganese absorption of maize during growth and maturity is primarily attributed to the earlier manganese accumulation in intercropped maize by 2.63 to 4.35 days, and a reduction of 21.95% in the maximum manganese accumulation rate. The study found that manganese accumulation dynamics vary significantly depending on the crop family. Intercropping Sedum alfredii with maize enhances land-use efficiency and reduces manganese uptake by crops, making it a promising strategy for remediating manganese-contaminated farmland near industrial areas. © 2024 Society of Chemical Industry.

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.

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.

Overexpression of ZNT1 and NRAMP4 from the Ni Hyperaccumulator Noccaea caerulescens Population Monte Prinzera in Arabidopsis thaliana Perturbs Fe, Mn, and Ni Accumulation.

Metalliferous soils are characterized by a high content of metal compounds that can hamper plant growth. The pseudometallophyte Noccaea caerulescens is able to grow on metalliferous substrates by implementing both tolerance and accumulation of usually toxic metal ions. Expression of particular transmembrane transporter proteins (e.g., members of the ZIP and NRAMP families) leads to metal tolerance and accumulation, and its comparison between hyperaccumulator N. caerulescens with non-accumulator relatives Arabidopsis thaliana and Thlaspi arvense has deepened our knowledge on mechanisms adopted by plants to survive in metalliferous soils. In this work, two transporters, ZNT1 and NRAMP4, expressed in a serpentinic population of N. caerulescens identified on the Monte Prinzera (Italy) are considered, and their expression has been induced in yeast and in A. thaliana. In the latter, single transgenic lines were crossed to test the effect of the combined over-expression of the two transporters. An enhanced iron and manganese translocation towards the shoot was induced by overexpression of NcZNT1. The combined overexpression of NcZNT1 and NcNRAMP4 did perturb the metal accumulation in plants.

Manganese translocation across an in vitro model of human villous trophoblast

Manganese translocation across an in vitro model of human villous trophoblast

The structural basis of bacterial manganese import.

Metal ions are essential for all forms of life. In prokaryotes, ATP-binding cassette (ABC) permeases serve as the primary import pathway for many micronutrients including the first-row transition metal manganese. However, the structural features of ionic metal transporting ABC permeases have remained undefined. Here, we present the crystal structure of the manganese transporter PsaBC from Streptococcus pneumoniae in an open-inward conformation. The type II transporter has a tightly closed transmembrane channel due to "extracellular gating" residues that prevent water permeation or ion reflux. Below these residues, the channel contains a hitherto unreported metal coordination site, which is essential for manganese translocation. Mutagenesis of the extracellular gate perturbs manganese uptake, while coordination site mutagenesis abolishes import. These structural features are highly conserved in metal-specific ABC transporters and are represented throughout the kingdoms of life. Collectively, our results define the structure of PsaBC and reveal the features required for divalent cation transport.

HYGIENIC SUBSTANTIATION FOR THE POSSIBILITY TO USE OF SEWAGE SLUDGE AS AN ORGANIC FERTILIZER

Introduction. Nowadays, in front of large cities, there is an acute problem for finding ways of environmentally safely dispose of accumulated sewage sludge and the possibility of its use. The most profitable way to utilize sewage sludge is to use them as organic fertilizers in agricultural production due to the high content of biogenic elements (nitrogen, phosphorus, potassium) and organic substances in their composition. However, the presence of heavy metals, pathogens, and other toxicants necessitates the study at the regional level the possibility of using these sediments as fertilizers. In each specific case, it is necessary to apply a scientific approach to the use of sewage sludge, since their composition is characterized by a qualitative and quantitative variation of chemical compounds. The purpose of the study was a hygienic justification for the possibility of using sludge for wastewater treatment from the municipal facilities in agricultural production as an organic fertilizer. Material and methods. The object of the study was sludge after treatment with flocculants and centrifugation and sludge stored on the sites of Lviv municipal facilities for 1, 6 and 18 months. In the experiment, the distribution of sludge components in the “plant-soil” dynamic system, as well as the degree of their accumulation in test plants, was determined. Quantitative determination of the of chemical elements content in samples of sludge and phytomass was carried out by atomic absorption spectrophotometry. Results. The effectiveness of the use of sludge from the municipal facilities for wastewater treatment in agricultural production as an organic fertilizer has been studied. It was found that the sludge dose of 50 tons/ha, using immediately after centrifuge, can not be used in the fields as a fertilizer. This dose caused a high phytotoxic effect on plants. The dose of used sludge (30 tons/ha after 1.5 years of maturing on silty areas) had a less pronounced phytotoxic effect, but the fact of fluorine, lead, cadmium, arsenic, mercury and manganese translocation from soil into the plants in high quantities was observed. This dose also cannot be used in the fields as a fertilizer. The use of a smaller dose should be justified by additional experiments.

Hygienic substantiation for the possibility to use of sewage sludge as an organic fertilizer

Introduction. Nowadays, in front of large cities, there is an acute problem for finding ways of environmentally safely dispose of accumulated sewage sludge and the possibility of its use. The most profitable way to utilize sewage sludge is to use them as organic fertilizers in agricultural production due to the high content of biogenic elements (nitrogen, phosphorus, potassium) and organic substances in their composition. However, the presence of heavy metals, pathogens, and other toxicants necessitates the study at the regional level the possibility of using these sediments as fertilizers. In each specific case, it is necessary to apply a scientific approach to the use of sewage sludge, since their composition is characterized by a qualitative and quantitative variation of chemical compounds. The purpose of the study was a hygienic justification for the possibility of using sludge for wastewater treatment from the municipal facilities in agricultural production as an organic fertilizer. Material and methods. The object of the study was sludge after treatment with flocculants and centrifugation and sludge stored on the sites of Lviv municipal facilities for 1, 6 and 18 months. In the experiment, the distribution of sludge components in the “plant-soil” dynamic system, as well as the degree of their accumulation in test plants, was determined. Quantitative determination of the of chemical elements content in samples of sludge and phytomass was carried out by atomic absorption spectrophotometry. Results. The effectiveness of the use of sludge from the municipal facilities for wastewater treatment in agricultural production as an organic fertilizer has been studied. It was found that the sludge dose of 50 tons/ha, using immediately after centrifuge, can not be used in the fields as a fertilizer. This dose caused a high phytotoxic effect on plants. The dose of used sludge (30 tons/ha after 1.5 years of maturing on silty areas) had a less pronounced phytotoxic effect, but the fact of fluorine, lead, cadmium, arsenic, mercury and manganese translocation from soil into the plants in high quantities was observed. This dose also cannot be used in the fields as a fertilizer. The use of a smaller dose should be justified by additional experiments.

Synthesis of Mn3O4 nano complex using aqueous extract of Helianthus annuus seed cake and its effect on biological growth of Vigna radiata

Manganese Oxide complex (MnO3O4) nanoparticles were successfully synthesized by bio-synthesis method using Manganese Acetate as the precursor, mediated by aqueous extract of Helianthus annuus seed cake. The XRD pattern confirms the crystalline nature with tetragonal phase having the average particle size 57 nm. FTIR analysis reveals the presence of Manganese oxide and the absorption peak around 650 nm and 613 nm is assigned to Mn-O stretching. From UV analysis the band gap energy is calculated as 1.47eV. SEM and TEM analysis of the specimen showed, the distribution of nanoparticles is spherical in the range of 10 nm to 70 nm. VSM studies confirm the soft magnetic nature of the sample. The synthesized MnO nanoparticles were incorporated to the sandy loam soil to check the biological growth of Vigna Radiata (Green gram) .Growth attributes measured were plant height, number of leaves, shoot length etc. Germination parameters were calculated based on the observations by POT studies. Harvested plant samples were tested for its phytochemical and biochemical compounds. The results showed an increasing trend of total chlorophyll content and decreased protein content in the MnO treated sample with reference to the untreated plant. The manganese deficiency increased the root surface area due to increased consumption, reduced the amount of manganese translocation caused diminished shoot growth, and yielded an increased root ratio.

Manganese translocation and concentration on Quercus cerris decomposing leaf and wood litter by an ascomycetous fungus: an active process with ecosystem consequences?

Decomposing fungi translocate manganese (Mn) as demonstrated by the fact that Mn has been found to accumulate on decomposing leaves associated with individual fungal hyphae forming insoluble Mn(III,IV) oxides that remain concentrated in diffuse patches. Here, we studied Mn translocation and precipitation by the saprophytic fungus Alternaria sp. strain FBL507 both on naturally decomposing oak leaves and in vitro experiments. Manganese was translocated and precipitated in beads and encrustations along the fungal hyphae. The combination of X-ray diffraction and scanning electron microscopy-energy dispersive X-ray spectroscopy chemical data showed that the precipitates found on leaves were rhodochrosite (MnCO3), birnessite ([Na, Ca, K]Mn2O4× 1.5H2O) and possibly Mn oxalate. The precipitates on wood were an amorphous Mn-O compound, probably MnO. Thus, Mn oxidation state in the precipitates spanned from +2 to +4, with +3 and +4 only in the birnessite on the leaves. In vitro experiments showed that Mn precipitates formed in living hyphae, suggesting the possibility that Mn precipitation is actively produced by the fungus. Such a possibility raises interesting questions regarding the role of readily available Mn in the activity of saprophytic fungi and other soil microorganisms, such as would result in a large involvement of Mn in the cycles of the major nutrient elements.

Phytoremediation capability of nickel and manganese polluted soil by Sorghum biocilor L.

A pot experiment was conducted based on a factorial study and complete random block design with three replicates to investigate the phytoremediation potential of Sorghum biocilor L. in soils polluted with nickel and manganese during 2017-2018. The first factor was nickel nitrate (0, 60, and 120 mg kg-1 soil) and the second factor comprised of manganese sulphate (0, 50, and 100 µM). The characteristics under investigation were shoot height, root length, shoot dry weight, root dry weight, nickel concentration of shoots and roots, manganese concentration of shoots and roots, and nickel and manganese translocation factors. Findings suggested that under nickel and manganese stress, shoot height, root length, shoot dry weight, and root dry weight reduced. Also, with an increase in the soil nickel and manganese, so did the concentration of these heavy metals in roots and shoots of the plants under study. Maximum effect of nickel and manganese were recorded in the treatments comprising 120 mg Kg-1 Nickel and 100 µM manganese sulphate, respectively while compared with nickel, manganese caused less damage to the plants under study. Application of nickel to the soil increased the translocation factor while there was no difference between the two levels of nickel applied. On the other hand, application of manganese did not affect the translocation factor compared to the control and the translocation factors for both elements were less than 1. Therefore, based on the findings of the study, sorghum showed a relatively good tolerance to nickel and manganese, the absorbed nickel and manganese were mostly concentrated in the plant root, and Sorghum biocilor L. is not recommended for phytoremediation.

カンキツにおける微量要素の吸収, 移行に関する研究(第1報) : 温州ミカン幼樹におけるマンガン, 亜鉛, 鉄の吸収, 移行に及ぼす施用形態およびリン酸施用量の影響

カンキツにおける微量要素の吸収, 移行に関する研究(第1報) : 温州ミカン幼樹におけるマンガン, 亜鉛, 鉄の吸収, 移行に及ぼす施用形態およびリン酸施用量の影響

Silicon decreases both uptake and root-to-shoot translocation of manganese in rice.

Silicon (Si) is known to alleviate manganese (Mn) toxicity in a number of plant species; however, the mechanisms responsible for this effect are poorly understood. Here, we investigated the interaction between Si and Mn in rice (Oryza sativa) by using a mutant defective in Si uptake. Silicon alleviated Mn toxicity in the wild-type (WT) rice, but not in the mutant exposed to high Mn. The Mn concentration in the shoots was decreased, but that in the roots was increased by Si in the WT. In contrast, the Mn concentration in the roots and shoots was unaffected by Si in the mutant. Furthermore, Si supply resulted in an increased Mn in the root cell sap, decreased Mn in the xylem sap in the WT, but these effects of Si were not observed in the mutant. A short-term labelling experiment with (54)Mn showed that the uptake of Mn was similar between plants with and without Si and between WT and the mutant. However, Si decreased root-to-shoot translocation of Mn in the WT, but not in the mutant. The expression of a Mn transporter gene for uptake, OsNramp5, was unaffected by a short exposure (<1 d) to Si, but down-regulated by relatively long-term exposure to Si in WT. In contrast, the expression of OsNramp5 was unaffected by Si in the mutant. These results indicated that Si-decreased Mn accumulation results from both Si-decreased root-to-shoot translocation of Mn, probably by the formation of Mn-Si complex in root cells, and uptake by down-regulating Mn transporter gene.

Cucumber metal tolerance protein CsMTP9 is a plasma membrane H⁺-coupled antiporter involved in the Mn²⁺ and Cd²⁺ efflux from root cells.

Members of the plant metal tolerance protein (MTP) family have been classified into three major groups - Zn-CDF, Mn-CDF and Zn/Fe-CDF - however, the selectivity of most of the MTPs has not been confirmed yet. Cucumber gene CsMTP9 encoding a putative CDF transporter homologous to members of the Mn-CDF cluster is expressed exclusively in roots. The relative abundance of CsMTP9 transcript and protein in roots is significantly increased under Mn excess and Cd. Immunolocalization with specific antibodies revealed that CsMTP9 is a plasma membrane transporter that localizes to the inner PM domain of root endodermal cells. The plasma membrane localization of CsMTP9 was confirmed by the expression of the fusion proteins of GFP (green fluorescent protein) and CsMTP9 in yeast and protoplasts prepared from Arabidopsis cells. In yeast, CsMTP9 transports Mn(2+) and Cd(2+) via a proton-antiport mechanism with an apparent Km values of approximately 10 μm and 2.5 μm for Mn(2+) and Cd(2+) , respectively. In addition, CsMTP9 expression in yeast rescues the Mn- and Cd-hypersensitive phenotypes through the enhanced efflux of Mn(2+) and Cd(2+) from yeast cells. Similarly, the overexpression of CsMTP9 in A. thaliana confers increased resistance of plants to Mn excess and Cd but not to other heavy metals and leads to the enhanced translocation of manganese and cadmium from roots to shoots. These findings indicate that CsMTP9 is a plasma membrane H(+) -coupled Mn(2+) and Cd(2+) antiporter involved in the efflux of manganese and cadmium from cucumber root cells by the transport of both metals from endodermis into vascular cylinder.

A polarly localized transporter for efficient manganese uptake in rice.

Manganese is an essential metal for plant growth. A number of transporters involved in the uptake of manganese from soils, and its translocation to the shoot, have been identified in Arabidopsis and rice. However, the transporter responsible for the radial transport of manganese out of root exodermis and endodermis cells and into the root stele remains unknown. Here, we show that metal tolerance protein 9 (MTP9), a member of the cation diffusion facilitator family, is a critical player in this process in rice (Oryza sativa). We find that MTP9 is mainly expressed in roots, and that the resulting protein is localized to the plasma membrane of exo- and endodermis cells, at the proximal side of these cell layers (opposite the manganese uptake transporter Nramp5, which is found at the distal side). We demonstrate that MTP9 has manganese transport activity by expression in proteoliposomes and yeast, and show that knockout of MTP9 in rice reduces manganese uptake and its translocation to shoots. We conclude that at least in rice MTP9 is required for manganese translocation to the root stele, and thereby manganese uptake.

OsNRAMP5 contributes to manganese translocation and distribution in rice shoots.

Manganese (Mn) is an essential micronutrient for plants playing an important role in many physiological functions. OsNRAMP5 is a major transporter responsible for Mn and cadmium uptake in rice, but whether it is involved in the root-to-shoot translocation and distribution of these metals is unknown. In this work, OsNRAMP5 was found to be highly expressed in hulls. It was also expressed in leaves but the expression level decreased with leaf age. High-magnification observations revealed that OsNRAMP5 was enriched in the vascular bundles of roots and shoots especially in the parenchyma cells surrounding the xylem. The osnramp5 mutant accumulated significantly less Mn in shoots than the wild-type plants even at high levels of Mn supply. Furthermore, a high supply of Mn could compensate for the loss in the root uptake ability in the mutant, but not in the root-to-shoot translocation of Mn, suggesting that the absence of OsNRAMP5 reduces the transport of Mn from roots to shoots. The results suggest that OsNRAMP5 plays an important role in the translocation and distribution of Mn in rice plants in addition to its role in Mn uptake.

Development of Lymantria dispar affected by manganese in food.

We studied the response of gypsy moth (Lymantria dispar (Linnaeus) (Lepidoptera: Lymantriidae)) to the content of manganese in food in the laboratory breeding of caterpillars. The food of the caterpillars {Betula pendula Roth (Fagales: Betulaceae) leaves} was contaminated by dipping in the solution of MnCl2 · 4H2O with manganese concentrations of 0, 0.5, 5 and 10 mg ml(-1), by which differentiated manganese contents (307; 632; 4,087 and 8,124 mg kg(-1)) were reached. Parameters recorded during the rearing were as follows: effect of manganese on food consumption, mortality and length of the development of caterpillars, pupation and hatching of imagoes. At the same time, manganese concentrations were determined in the offered and unconsumed food, excrements, and exuviae of the caterpillars, pupal cases and imagoes by using the AAS method. As compared with the control, high manganese contents in the food of gypsy moth caterpillars affected the process of development particularly by increased mortality of the first instar caterpillars (8 % mortality for caterpillars with no Mn contamination (T0) and 62 % mortality for subjects with the highest contamination by manganese (T3)), by prolonged development of the first-third instar (18.7 days (T0) and 27.8 days (T3)) and by increased food consumption of the first-third instar {0.185 g of leaf dry matter (T0) and 0.483 g of leaf dry matter (T3)}. The main defence strategy of the caterpillars to prevent contamination by the increased manganese content in food is the translocation of manganese into frass and exuviae castoff in the process of ecdysis. In the process of development, the content of manganese was reduced by excretion in imagoes to 0.5 % of the intake level even at its maximum inputs in food.

Chromium Phytotoxicity in Radish (Raphanus sativus): Effects on Metabolism and Nutrient Uptake

In the present investigation, chromium (VI) induced toxicity on metabolic activity and translocations of nutrients in radish were evaluated under controlled glass house conditions. Chromium was found to induce toxicity and significantly affect plant growth and metabolic activity. Excess of chromium (0.4 mM) caused a decrease in the concentration of iron in leaves (from 134.3 to 71.9 μg g(-1) dw) and significant translocation of sulphur, phosphorus and zinc. Translocation of manganese, copper and boron were less affected from root to stem. After 15 days of Cr exposure, maximum accumulation of Cr was found in roots (327.6 μg g(-1) dw) followed by stems (186.8 μg g(-1) dw) and leaves (116.7 μg g(-1) dw) at 0.4 mM Cr concentration. Therefore, Cr may affect negatively not only production, but also the nutritive quality of the radish; likewise, higher Cr content may cause health hazards for humans.

CHROMIUM TOXICITY IN HYBRID EUCALYPTUS (EUCALYPTUS UROPHYLLA S. T. BLAKE X GRANDIS W. HILL EX. MAIDEN) CUTTINGS

A greenhouse experiment was carried out to evaluate chromium (Cr) toxicity in urograndis (Eucalyptus urophylla S. T. Blake x grandis W. Hill ex. Maiden). Chromium nitrate was amended to Clark's nutrient solution (0.00, 0.04, 0.08, 0.16, 0.32 and 0.64 mmol L−1 Cr), which was used to breed one urograndis cutting per pot (four replications). Regression analysis revealed that Cr rates of 0.08 mmol L−1 or higher significantly decreased (P < 0.01) dry matter yield of shoot and root. Chromium accumulation order in plant was: root > stem > leaves. Critical Cr toxicity level in leaves was 0.74 mg kg−1. Uptake and translocation of nutrients were affected differently by Cr. Mostly have their uptake reduced due to root damage. Magnesium, iron and manganese translocation increases, supposedly to maintain normal photosynthetic activity. Wilting is the main visual symptom of Cr toxicity. Urograndis may be suitable for contaminated sites phytostabilization and receive industrial waste fertilization.

Uptake and Translocation of Manganese by Native Tree Species in a Constructed Wetland Treating Landfill Leachates

A surface flow constructed wetland was used to treat stormwater runoff from surrounding watersheds which are comprised primarily of commercial properties and two former landfills. The uptake of manganese by red maple, white birch and red spruce trees growing under flooded soil conditions in the constructed wetland was compared to that of the same trees growing under well drained soil conditions in a nearby reference site. The seasonal variability of manganese and its distribution in different compartments of these trees (leaves, twigs, branches, trunk wood, trunk bark and roots) were studied. The average manganese concentrations in the aboveground compartments of red maple, white birch and red spruce trees were within the range of manganese concentrations reported in the literature for these trees. The concentrations of manganese in the aboveground compartments of red maple, white birch and red spruce trees in the reference site were significantly greater than those in the constructed wetland (with the exception of manganese concentrations in the trunk wood of red maple trees) because of the acidic soil conditions of the reference site. The percent distribution of manganese in the aboveground compartments of trees did not vary during the growing season. Higher concentrations of manganese were present in the trunk bark and either the leaves or twigs of species on both the constructed wetland and the reference site regardless of the sampling date.