Search

Manganese deficiency in soybean [Glycine max (L.) Merr.] reduces seed yield and alters the oil profile. The objective of this study was to evaluate the effect of foliar Mn fertilizer on seed yield, protein and oil concentration, and the oil profile of transgenic high-oleic soybean ('Plenish') and soybean with a normal oil profile (referred to here as "conventional"). Research trials were established in 2014 and 2015 at two locations in Ohio. Treatments included soybean cultivar (four to six Plenish cultivars and two conventional cultivars) and foliar Mn fertilizer application at the R3 soybean growth stage (none, Mn--SO4, and Mn--EDTA). In 2014, the Mn--SO4 application increased soybean seed yield by 140 kg ha-1 at the Wood County location where soybean plants were deficient in Mn. Although Mn-SO4 also supplies S, no S deficiencies were detected. At the other three site-years, soybean seed yield was not affected by Mn application. Manganese application did not influence the oil or protein content of the soybean seed or alter the oil profile. The high-oleic cultivars produced similar yield to the conventional cultivars at the Wood County location both years. In 2014 and 2015 at the Clark County location, the high-oleic cultivars yielded 410 and 270 kg ha-1 less than cultivars with a conventional oil profile, respectively. Plenish soybean cultivars did not need to be managed differently from the conventional soybean cultivars tested in terms of Mn foliar application. [ABSTRACT FROM AUTHOR]

To cope with manganese (Mn) deficiency, plants have evolved an efficient transport system to uptake and redistribute Mn. However, the underlying molecular mechanisms remain to be demonstrated., We carried out a forward genetic screen in a root high-affinity Mn transporter nramp1 mutant background in Arabidopsis thaliana and identified an uncharacterized Mn transport NRAMP2. We investigated the effect of nramp2 mutation on root growth and reactive oxygen species ( ROS) accumulation and we also examined the NRAMP2 expression pattern, and the subcellular localization and transport activity of NRAMP2., Mutation of NRAMP2 impaired plant growth, while overexpression of NRAMP2 improved plant growth under low Mn conditions. In the nramp2-1nramp1 double mutant, Mn deficiency inhibited root cell elongation and root hair development, which was associated with increased hydrogen peroxide (H2O2) accumulation. NRAMP2 is preferentially localized to the trans-Golgi network. NRAMP2 has Mn influx transport activity in yeast, and mutation of NRAMP2 led to greater Mn retention in roots., Our results suggest that under Mn-deficient conditions, increased accumulation of H2O2 is partially responsible for the root growth inhibition and NRAMP2 is involved in remobilization of Mn in Golgi for root growth. [ABSTRACT FROM AUTHOR]

Background and aims: We aimed to investigate the effects of root carboxylate exudation in the interaction between Azospirillum brasilense and Zea mays. We hypothesized that root carboxylate exudation is a mechanism that increases colonization of the maize rhizosphere by A. brasilense and that carboxylate exudation would increase at a low soil phosphorus (P) availability. Methods: We conducted a greenhouse experiment, using maize seeds inoculated and uninoculated with A. brasiliense. Seeds were planted in pots, supplied with nutrient solution, varying in P concentration. After 45 days we measured total plant biomass, root length and area, plant nutrient status, and the root carboxylate-exudation rate. Results: Inoculation increased the root length and area, and this effect increased with increasing P supply. Inoculated plants also showed an increased root carboxylate-exudation rate. For inoculated treatments, the exudation rate was positively correlated with root architecture parameters; however, it was negatively correlated with leaf manganese concentration, a proxy for the amount of carboxylates in the rhizosphere. Conclusion: Inoculation of A. brasilense stimulated root carboxylate exudation, which was positively correlated with root length and area. These positive correlations are probably mediated by the effect of carboxylates on the rhizosphere microbial community. This indicates a positive feedback in which A. brasilense inoculation stimulates root carboxylate exudation, influencing the rhizosphere microbial community. It results in positive effects on maize root architecture. The root length of inoculated plants was positively correlated with P supply, indicating that P supply positively affects the microbial community, modulating the interaction between A. brasilense and Z. mays. [ABSTRACT FROM AUTHOR]

Soil micronutrient deficiency adversely affects crop production in intensive agriculture. However, information on the spatial variability of key micronutrients in intensively cultivated regions of India is limited. Thus, the present study was carried out in the Trans-Gangetic Plains (TGP) region of India with the hypothesis that spatial variability of micronutrient availability is high due to small farms and varied management. The major objectives of the study were (i) to assess the spatial variability of plant available micronutrients, viz . extractable zinc (Zn), copper (Cu), manganese (Mn) and iron (Fe) at a regional scale through geostatistical methods, (ii) to develop distribution maps for soil micronutrients using ordinary kriging and (iii) to assess the relationships of micronutrient availability with several soil properties. A total of 5638 soil samples, representative of the surface (0–15 cm) horizon were collected (covering Inceptisols, Entisols, Alfisols and Aridisols) during April to June between 2011 and 2014 from farms in 21 districts of the TGP. For each micronutrient, semivariograms were calculated and their main parameters (nugget effect, sill and range) were obtained. Moderate spatial dependence for extractable Zn, Cu and Fe and strong spatial dependence for extractable Mn were recorded. The nugget/sill ratio values were 0.60, 0.37, 0.34 and 0.19 for extractable Zn, Fe, Cu and Mn, respectively. Available Fe, Zn, Mn and Cu deficiencies (including acute deficiencies) were observed in 28, 15, 14 and 13% of soil samples, respectively. Soil pH showed significant and negative correlations with the concentrations of extractable Zn, Cu, Mn and Fe; whereas the correlation was significant and positive with soil organic carbon (SOC) concentration. The distribution maps generated could be used as a guide for precise and site-specific micronutrient management in the study region. [ABSTRACT FROM AUTHOR]

Chemical forms of Mn and Zn in the soil and its availability to soybeans grown in a Latosol for 12 years under different tillage systems were studied. The effects of these systems on Mn complexation by soil humic acid (HA) were also evaluated. The field experiment was carried out in a randomized block (three blocks) split-plot experimental design. The main treatments consisted of four tillage systems and the secondary, of three soil sampling depths (0.00–0.05 m, 0.05–0.10 m and 0.10–0.20 m). The tillage systems were no tillage (NT), conventional tillage (CT), minimum tillage (MT) and NT with scarification, every three years. The results presented refers to the last 2 years of the experiment, 2000 and 2001. In average numbers, the Zn content of the 0.00–0.05 m layer was lower in soil under CT (2 mg kg −1 ), compared to the other tillage systems (NT and NT with scarification = 2.7 and MT = 2.8 mg kg −1 ). In general, Zn percentages in exchangeable, organic, oxides and residual forms were not modified by the tillage systems. In turn, the Mn content of the soil surface layer under the NT was higher than in the soil under CT. Mn contents extracted with DTPA were 11 and 5.2 mg kg −1 in the soil under NT and CT, respectively. The Mn contents extracted with Mehlich I, Mehlich III and HCl in the soil under CT were 20.8, 8.7 and 16.8 mg kg −1 , respectively. In the soil under NT, the contents extracted with the same extractors were 27.9, 15 and 29.2 mg kg −1 . In the surface layer, higher Mn percentages in the organic fraction were found in the soil under NT (19.2%) and NT with scarification (15.9%) than in soil under CT (11.8%). The Mn content of this layer was also positively correlated with the soil organic matter, but none of the extractors used (DTPA-TEA pH 7.3, HCl 0.1 mol L −1 , Mehlich I and III) properly assessed the levels of Mn and Zn available to plants, suggesting the need for further studies. It was not observed presence of Mn in the HA samples by electron paramagnetic resonance (EPR). Since the digestion by nitro-perchloric acid of the HA samples showed the presence of Mn in these samples, it strengthens the hypothesis that Mn was bound to the HA in the form of stable complexes (covalent bonds), since this form of Mn cannot be detected by EPR. During soybean cultivation, Mn concentrations in the leaves did not vary with the tillage methods and were near or below the range considered adequate for the crop. Furthermore, visual symptoms of Mn deficiency in the leaves were observed in the initial stages of plant development, regardless of treatment. This suggests the need for new correlation and calibration studies for micronutrients in Brazil, especially for soils cultivated under the NT. [ABSTRACT FROM AUTHOR]

Background: Manganese (Mn) has several essential functions in plants, including a role as cofactor in the oxygen evolving complex (OEC) of photosystem II (PSII). Manganese deficiency is a major plant nutritional disorder in winter cereals resulting in significant yield reductions and winter kill in more severe cases. Among the winter cereals, genotypes of winter barley are known to differ considerably in tolerance to Mn deficiency, but the genes controlling the Mn deficiency trait remains elusive. Results: Experiments were conducted using 248 barley varieties, cultivated in six distinct environments prone to induce Mn deficiency. High-throughput phenotyping for Mn deficiency was performed by chlorophyll a (Chl a) fluorescence analysis to quantify the quantum yield efficiency of PSII. High-throughput phenotyping in combination with ICP-OES based multi-element analyses allowed detection of marker-trait associations by genome wide association (GWA) mapping. Several key candidate genes were identified, including PSII subunit proteins, germin like proteins and Mn superoxide dismutase. The putative roles of the encoded proteins in Mn dependent metabolic processes are discussed. Conclusions: Fifty-four candidate genes were identified by Chl a fluorescence phenotyping and association genetics. Tolerance of plants to Mn deficiency, which is referred to as Mn efficiency, appeared to be a complex trait involving many genes. Moreover, the trait appeared to be highly dependent on the environmental conditions in field. This study provides the basis for an improved understanding of the parameters influencing Mn efficiency and is valuable in future plant breeding aiming at producing new varieties with improved tolerance to cultivation in soil prone to induce Mn deficiency. [ABSTRACT FROM AUTHOR]

Manganese (Mn) is an essential plant micronutrient with an indispensable function as a catalyst in the oxygen-evolving complex (OEC) of photosystem II (PSII). Even so, Mn deficiency frequently occurs without visual leaf symptoms, thereby masking the distribution and dimension of the problem restricting crop productivity in many places of the world. Hence, timely alleviation of latent Mn deficiency is a challenge in promoting plant growth and quality. We describe here the key mechanisms of Mn deficiency in plants by focusing on the impact of Mn on PSII stability and functionality. We also address the mechanisms underlying the differential tolerance towards Mn deficiency observed among plant genotypes, which enable Mn-efficient plants to grow on marginal land with poor Mn availability. [ABSTRACT FROM AUTHOR]

Aims: Using Fe- and Mn-deficient Solanum lycopersicum plants, we investigated the effects of Fe and Mn foliar fertilisers, either individually or combined, on plant biomass, leaf chlorophyll and metal micronutrient levels in leaves and roots. Methods: Plants were grown in hydroponics with different combinations of 0 or 45 μM Fe and 0 or 4.6 μM Mn. Foliar fertiliser formulations (9 mM FeSO and/or 3 mM MnSO, supplemented with a surfactant) were applied in three consecutive doses. Fertilisation was applied to the first three leaf levels, while upper leaf levels were left untreated. Results: Iron and Mn deficiency led to characteristic symptoms. Foliar treatments increased concentrations of Fe and Mn, biomass and chlorophyll in treated leaves, although re-greening was incomplete. Approximately 11-12 % of the Fe increase was in roots (likely mediated via phloem transport), but no Fe increase occurred in untreated leaves. Regarding Mn, a 2 % increase occurred in untreated leaves, but no increase occurred in roots. Conclusions: Iron fertilisation was effective not only in leaves treated with the fertiliser but also in roots, whereas Mn fertilisation had major effects on treated leaves and minor effects on untreated ones. The combined application of Fe + Mn was not detrimental to Fe- or Mn-deficient plants. [ABSTRACT FROM AUTHOR]

The visual symptomatology of nutriment deficiencies, like iron (Fe) and manganese (Mn) in plant leafs is similar in their coloration and the kind of leaf they present on. A method based on the analysis of digital images of the leaves, capable to discriminate the differences of such deficiencies is required. The aim of this research was to analyze digital images of common bean (Phaseolus vulgaris L. var. Cacahuate), in order to identify differences in the Fe and Mn lesions in the initial development stage, when it is possible to revert damages with fertilization. To do so, we used a classifier created with probabilistic neuronal networks. The experimental treatments were: 1) partial deficiency (DP) of Fe (50 %); 2) DP of Mn (50 %); 3) total deficiency (DT) of Fe (0 %); 4) DT of Mn (0 %); 5) Fe/Mn interaction (0 % Fe, 0 % Mn); 6) control (100 % Fe, 100 % Mn), with 10 repetitions; Steiner solution was used as reference. The mean values of eight color and three texture variables from digital images of six common bean leaf samples were obtained; these were of 100×100 pixels (360 total samples) in 74 dds. These mean values were used as entry variables to generate the classifiers with a cascade correlation algorithm of the Fe and Mn deficiency treatments. The classifiers that only considered textural characteristics had correct global classification of symptoms less or equal to 44 %. In contrast, the highest percentage of correct global classification of the classifiers in the test was of 76.6 % with six variables, which included texture and color characteristics, and six exit classes of difference treatments. The reduction of the number of classes did not increase the percentage of correct classification in the test. [ABSTRACT FROM AUTHOR]

Analysis and research on the nutrition of some Australian native plants as well as diagnostic analysis of failed native plant gardens reinforces the view that manganese (Mn) availability is a major factor in the edaphology and cultivation of Australian native species. Yellow Kandosol soils on sandstone show a unique endemic floral assemblage. These soils show low total soil Mn levels of only 20–30 mg/kg. Despite this, endemic species such asEucalyptus haemastomaandAcacia suaveolensshow greater foliar Mn levels (around 291 and 389 mg/kg, respectively) than iron (Fe) levels, with Fe/Mn ratios as low as 0.14 and 0.27. During pot trial work on artificial soils created from crushed sandstone and green waste compost that were designed to research phosphorus (P) and calcium (Ca) nutrition, some interesting data on Mn uptake were collected. Levels of foliar Mn as high as 1250 and 389 mg/kg, respectively, accumulated inE. haemastomaandA. suaveolenswhen soils were artificially acidified to pH 4.7 (CaCl2) using ferrous sulfate. These Mn levels were associated with visible toxicity symptoms in foliage ofE. haemastomabut not inA. suaveolens. Foliar Mn in both species showed a strong inverse correlation (R2 > 0.93) with soil pH. Previous research has shown that eucalypts from this floral assemblage are prone to Mn toxicity when grown in conditions of high soil Mn availability. Diagnostic analysis of soils and foliage for a client with horticultural problems in a native plant landscape showed severe chlorosis in a wide range of native species due to Mn deficiency induced by neutral soil pH (around 7.0 in CaCl2). Such soil pHs are considerably greater than those of the plant’s natural distribution. Despite apparently elevated soil P and the appearance of what looked like P toxicity, foliar P levels were not sufficiently elevated to conclude acute P toxicity but rather simple and severe Mn deficiency. The work suggests that induced Mn deficiency and toxicity may be underdiagnosed problems in the cultivation of many Australian native plants. [ABSTRACT FROM PUBLISHER]

Manganese (Mn) deficiency is commonly connected with soil properties, and application of Mn is frequently performed to winter barley (Hordeum vulgare L.) in fields with a history of deficiency. Since the availability of Mn also is affected by seasonal variations, there is a risk of excessive application in some seasons while the application is not sufficient in other seasons in such fields. The objective of this study was to investigate the effect of foliar application of Mn in autumn and early spring on barley winter hardiness, in combination with or without N application in autumn. We also evaluated a commercially available Mn-scanner as a tool to identify the need for Mn application. Two field experiments per growing season were performed in south Sweden in 2010-2011 and 2011-2012 in fields where Mn deficiency often occurs. Foliar applications of various Mn products were made once (in October) or twice (in October and in March the following year). A single dose of 0 or 30kgha-1 N was applied, as NNO3, in October. Barley leaves were collected and Mn status determined with the NN-Easy55 Mn-scanner. Yield was determined in the field experiments in 2011-2012. Our results showed that the requirement of Mn application varied between sites and seasons and was affected by N supply. Mn application increased the winter survival by 33% and the grain yield by 36% in the barley plants with the lowest Mn status in autumn. The risk of Mn deficiency increased when N (NO3N) was applied in autumn. In one of the harvested field experiments, yield was suppressed by N application in autumn and was recovered by Mn application. Repeated Mn applications might be required to increase winter survival and grain yield, especially when N has been applied in the autumn. To reach an optimal Mn application, tools such as the NN-Easy55 Mn-scanner can be used to monitor the Mn status of the plants. Thereby unnecessary application of Mn is prevented and sufficient amounts are applied during deficiency. [ABSTRACT FROM AUTHOR]

Background and aims: Manganese (Mn) deficiency represents a major plant nutritional disorder in winter cereals. The deficiency frequently occurs latently and the lack of visual symptoms prevents timely remediation and cause significant yield reductions. These problems prompted us to investigate chlorophyll (Chl) a fluorescence as a tool for diagnosis of latent Mn deficiency. Methods: Barley plants grown under controlled greenhouse conditions or in the field were exposed to different intensities of Mn deficiency. The responses were characterised by analysis of Chl a fluorescence, photosystem II (PSII) proteins and mineral elements. Results: Analysis of the Chl a fluorescence induction kinetics (FIK) revealed distinct changes long before any visual symptoms of Mn deficiency were apparent. The changes were specific for Mn and did not occur in Mg, S, Fe or Cu deficient plants. The changes in Mn deficient plants were accompanied by a marked reduction of the D1 protein in PSII. Foliar Mn application fully restored PSII functionality, ensured winter survival, and increased grain yields under field conditions. Conclusions: The efficiency and stability of PSII are markedly affected by latent Mn deficiency. Chlorophyll a fluorescence measurements constitute a powerful and valuable tool for diagnosis and remediation of latent Mn deficiency. [ABSTRACT FROM AUTHOR]

Abstract: In Tunisia, date orchards are being decimated by a disease called brittle leaf disease of unknown origin. Previous studies reported that affected soils, roots and leaves were manganese deficient. In this study, we investigated the biochemical and molecular response of MFC-affected date palms to the oxidative stress generated by manganese deficiency. Both the malondialdehyde (MDA) content which is indicative of lipid peroxidation and the activities of antioxidant enzyme were measured in affected leaves and roots. The expression profiles of oxidative stress-related genes encoding superoxide dismutases and peroxidases were also investigated. The data show that the MDA concentration increased but not significantly in affected leaves. However, such MDA increase was significant in roots of MFC-affected plants. The total superoxide dismutase (SOD) activity increased in affected leaves and roots, while RT-PCR experiments showed that MnSOD RNA decreased in affected leaves and roots unlike FeSOD and Cu/Zn-SOD RNA expression increased in these organs. In addition ascorbate peroxidase (APx) and glutathione peroxidase (GPx) RNA expression increased in diseased leaves and roots. [Copyright &y& Elsevier]

Abstract: Brittle leaf disease or maladie des feuilles cassantes (MFC) is a disorder affecting date palms (Phoenix dactylifera L.) which after a long declining process eventually leads to the death of the plant. No causal agent for the disease has been found so far but leaflets of affected palms are Mn-deficient despite the existence of adequate exchangeable Mn in the soils in which affected palms grow. The disease is specifically associated with an increase in a series of chloroplastic RNAs. A proteomic analysis of leaflets of affected and unaffected date palms showed differences in quantities of several proteins. Mn-binding PSBO and PSBP proteins, components of the oxygen-evolving complex of photosystem II, were decreased in affected tissue, reinforcing the relation between MFC and Mn deficiency. The quantities of other proteins were increased by disease suggesting a response to stress. [Copyright &y& Elsevier]

A 130-day hydroponic experiment was carried out in a glasshouse to examine whether manganese (Mn) concentration in the nutrient solution affects the nutritional status of olive plants and to find out whether the chlorophyll fluorescence technique is suitable to assess Mn toxicity and/or deficiency stress in olive plants prior to the appearance of these two nutritional disorders. For this purpose, chlorophyll fluorescence parameters (Fv/Fm and Fv/F0 ratios) were recorded every 40 days in the leaves of 'Kothreiki' and 'FS-17' olive cultivars, which were irrigated with Hoagland's nutrient solutions containing various Mn concentrations. In parallel the elongation of the main shoot of all experimental plants, as well as the concentrations of Mn, iron (Fe), zinc (Zn), boron (B), phosphorus (P), calcium (Ca), magnesium (Mg), and potassium (K) in their leaves were recorded. The following Mn treatments were applied: 0 μM Mn (to induce Mn deficiency), 40 μM Mn (to promote normal growth), and 640 μM Mn (to induce Mn toxicity). Our results indicated that not only the rate of shoot elongation but also the fluctuation with time of the leaf concentrations of all determined mineral elements (except for Mn) was not significantly affected by the Mn concentration in the nutrient solution, irrespectively of the cultivar. This was not observed with regard to the time variation of the Fv/Fm and Fv/F0 ratios, where the values of these parameters were significantly reduced in the 640 μM Mn treatment at the 80th and 130th day of the experiment in both olive cultivars, compared to the relevant previous ones (those of the days 0 and 40th), something which did not happen in the other two Mn treatments (0 and 40 μM). However, in none of the two cultivars tested and in any of the three Mn treatments (0, 40 and 640μM) the Fv/Fm and Fv/F0 ratios did not drop below the critical values of 0.8 and 4, respectively, even at the end of the experiment, where high Mn concentrations were found in the leaves of both cultivars treated with 640 μM Mn (616 μg g-1 d.w. in 'FS-17' and 734 μg g-1 d.w. in 'Kothreiki'). Symptoms of Mn toxicity (curling and brown speckles) were observed in the top leaves of both cultivars, after the 90th day of the experiment. At the same time, the final leaf Mn concentrations (those of the 130th day of the experiment) in plants grown under 0 μM Mn were 23 μg g-1 d.w. in 'FS-17' and 20 μg g-1 d.w. in 'Kothreiki', i.e., a little above of the deficiency range (<20 μg g-1 d.w.). At the 130th day, Mn concentration in nutrient solution, as well as Mn concentration in the leaves of both olive cultivars was negatively correlated with the leaf concentration of Fe and the values of the Fv/Fm and Fv/F0 ratios, and positively with the concentrations of Zn and P in the leaves. Finally, the periodical measurement of the Fv/Fm and Fv/F0 ratios was proved to be a non-reliable means to predict the appearance of the visible symptoms of Mn toxicity in olive leaves (although their values declined significantly at the 80th and 130th day of the experiment in both olive cultivars). [ABSTRACT FROM AUTHOR]

Manganese (Mn) deficiency may be induced by adding large quantities of iron (Fe), provided that soil manganese is marginally deficient. Results of a greenhouse study showed that iron soil application did not influence shoot dry matter yield of dry bean due to the fact that the iron:manganese ratio in aerial parts of dry bean was higher than 0.4. A foliar spray of 2% iron sulfate significantly reduced it probably due to the high level of shoot iron and iron:manganese ratio greater than 4. Iron application decreased concentration/uptake of shoot manganese due to the iron-manganese antagonistic relationships. Mangenese soil application is not an effective method in correction of manganese deficiency induced by iron fertilizers. Iron did not affect root manganese uptake, indicating that manganese absorption was not affected by iron application. Both manganese/iron soil tests are recommended in calcareous soils with manganese soil test in marginal range. [ABSTRACT FROM AUTHOR]

Barley (Hordeum vulgare) genotypes display a marked difference in their ability to tolerate growth at low manganese (Mn) concentrations, a phenomenon designated as differential Mn efficiency. Induction of Mn deficiency in two genotypes differing in Mn efficiency led to a decline in the quantum yield efficiency for both, although faster in the Mn-inefficient genotype. Leaf tissue and thylakoid Mn concentrations were reduced under Mn deficiency, but no difference between genotypes was observed and no visual Mn deficiency symptoms were developed. Analysis of the fluorescence induction kinetics revealed that in addition to the usual O-J-I-P steps, clear K and D steps were developed in the Mn-inefficient genotype under Mn deficiency. These marked changes indicated damages to photosystem II (PSII). This was further substantiated by state transition measurements, indicating that the ability of plants to redistribute excitation energy was reduced. The percentage change in state transitions for control plants with normal Mn supply of both genotypes was 9% to 11%. However, in Mn-deficient leaves of the Mn-inefficient genotypes, state transitions were reduced to less than 1%, whereas no change was observed for the Mn-efficient genotypes. Immunoblotting and the chlorophyll a/b ratio confirmed that Mn deficiency in general resulted in a significant reduction in abundance of PSII reaction centers relative to the peripheral antenna. In addition, PSII appeared to be significantly more affected by Mn limitation than PSI. However, the striking genotypic differences observed in Mn-deficient plants, when analyzing state transitions and fluorescence induction kinetics, could not be correlated with specific changes in photosystem proteins. Thus, there is no simple linkage between protein expression and the differential reduction in state transition and fluorescence induction kinetics observed for the genotypes under Mn deficiency. [ABSTRACT FROM AUTHOR]

Manganese (Mn) deficiency is an important plant nutritional disorder in many parts of the world. Barley (Hordeum vulgare) genotypes differ considerably in their ability to grow in soils with low Mn2+ availability. Differential genotypic Mn efficiency can be attributed to differences in Mn2+ uptake kinetics in the low nanomolar concentration range. However, the molecular basis for these differences has not yet been clarified. We present here the identification and characterization of the first barley gene encoding a plasma membrane-localized metal transport protein able to transport Mn2+. The gene is designated HvIRT1 (for IRON-REGULATED TRANSPORTER1) because it belongs to the ZIP gene family and has a high similarity to rice (Oryza sativa) OsIRT1. A novel yeast uptake assay based on inductively coupled plasma-mass spectrometry analysis of 31 different metal and metalloid ions showed that the HvIRT1 protein, in addition to Mn2+, also transported Fe2+/Fe3+, Zn2+, and Cd2+. Both Mn and iron deficiency induced an up-regulation of HvIRTI in two barley genotypes differing in Mn efficiency, but the expression levels in all cases were highest (up to 40%) in the Mn-efficient genotype. The higher expression of HvIRTI correlated with an increased Mn2+ uptake rate. We conclude that HvIRT1 is an important component controlling Mn2+ uptake in barley roots and contributes to genotypic differences in Mn2+ uptake kinetics. [ABSTRACT FROM AUTHOR]

Abstract: Manganese deficiency symptoms are more often observed in crops at early stages of growth since Mn2+ can be easily mobilized from the surface soil. The objectives of this study were to evaluate some of the popular rotation crops grown in Hungary for tolerance to low external Mn2+ levels and to determine the critical tissue concentration for Mn2+ deficiency during early stages of growth. Indicator plants of sunflower (Helianthus annuus L.) were grown with NPKCaMg-fertilization induced of 0.0425–0.0700gkg−1; of tobacco (Nicotiana tabacum L.) 0.0237–0.0337gkg−1; of triticale (x Triticosecale W.) 0.0103–0.0327g NH4-acetate+EDTA extractable soil Mn2+ kg−1; and were grown for 73, 50, and 191 days. The minimum Mn2+ concentration required in soil nutrient contents was 0.0425gkg−1 for sunflower, 0.0243gkg−1 for tobacco, and 0.0103gkg−1 for triticale. Sunflower, tobacco and triticale achieved optimum growth from 0.048 to 0.065gMn2+ kg−1, from 0.0249 to 0.0321gMn2+ kg−1, and from 0.0287 to 0.0296gMn2+ kg−1, respectively. Critical ABP''s dry weight Mn2+ concentration at early stages of growth was 0.0536gkg−1 in sunflower, 0.458gkg−1 in tobacco, and 0.1938gkg−1 in triticale. Our results demonstrate that the tolerance to low external Mn2+ (triticale <0.0302gkg−1; sunflower <0.0562gkg−1; tobacco <0.0693gkg−1) and the critical tissue Mn2+ levels for deficiency varied significantly among crop species tested. [Copyright &y& Elsevier]

Nickel (Ni) contamination occurred near a Ni refinery at Port Colbome, Ontario, on soils susceptible to Mn deficiency. Previous studies showed that adding limestone to remediate these soils induced Mn deficiency in plants. This greenhouse pot experiment was conducted with Welland loam and Quany muck soils to learn the application of MnSO4 needed when these soils were limed. Limestone application, along with Mn fertilizer, allowed normal growth of oat and red beet known as sensitive to Ni phytotoxicity and Mn deficiency. Strontium (Sr)-nitrate extractable Ni was a smooth function of slurry pH with much higher Ni extractable from the Welland loam than Quany muck. Ni phytotoxicity was severe at low pH for the Welland loam but it was generally prevented by liming. No severe Mn deficiency was observed in this experiment when nitrogen was applied as combination of urea, ammonia, and nitrates. Manganese fertilization greatly improved Mn uptake by both crops in both soils. [ABSTRACT FROM AUTHOR]

Manganese (Mn) deficiency is a major constraint of alkaline soils around the world, particularly for cultivation of durum wheat, which is more intolerant of low Mn levels than either common wheat or barley. Genetic variation for Mn efficiency exists in the current germplasm of durum wheat. Several restriction fragment length polymorphisms (RFLPs) previously shown to be linked to the Mel1 locus for Mn efficiency on chromosome 4HS of barley were tested on 88 selected F2 plants of the durum cross, `Stojocri 2' (Mn efficient) × `Hazar' (Mn inefficient). The Mel1 -linked RFLP marker Xcdo583a was closely linked to the trait and explained over 42% of the total variation for Mn efficiency in the `Stojocri 2'/`Hazar' F2 progeny. This marker has the potential to provide a valuable tool for the marker-assisted selection of Mn-efficient durum progeny derived from crosses with `Stojocri 2'. [ABSTRACT FROM AUTHOR]

Manganese deficiency in chloroplasts of Eureka lemon leaves resulted in 23% and 40% increase of chloroplast nitrogen and protein, respectively, on a chlorophyll unit basis. Acrylamide gel electrophoresis carried out on extracts of these chloroplasts disclosed also qualitative differences between the normal and deficient leaves. Calculated on chloroplast N basis there is an increase of 17% in the chloroplast protein under Mn deficiency. This increase apparently indicates a more intense protein synthesis in the Mn deficient chloroplasts. Hill activity of the -Mn leaves was about one-third of the analog control leaves. Manganese infiltration into detached but intact leaves restored the activity in the -Mn leaves up to 70% of the control. Lemon leaves affected by other macro- and micro-nutrient deficiencies did not respond to the manganese infiltration; therefore, the use of this infiltration method is suggested for the evaluation of the manganese nutrition status of citrus and probably other higher plants. [ABSTRACT FROM AUTHOR]