Mn Contents In Shoots Research Articles

Effects of Claroideoglomus etunicatum Fungus on the Growth Parameters of Maize (Zea mays L.) Plants under Boron Toxicity and Salt Stress

Soil salinity is an emerging phenomenon threatening arid and semiarid areas due to changing climatic events. Salinity, in combination with other elemental contaminants, can often harm crop performance and productivity. This experiment was conducted to evaluate the mitigating effect of Claroideoglomus etunicatum, an arbuscular mycorrhizal fungus (AMF), on combined boron (B) toxicity and salt stress symptoms in maize plants. After the stress and AMF treatments, plants were subjected to a wide range of analyses, such as AMF colonization rates, ion leakage, plant biomass, and concentration of B, phosphorus, sodium, potassium, iron, zinc, copper, and manganese in root and shoot tissues. The results showed that the combined stress did not affect the AMF colonization rate. AMF inoculation significantly increased plant biomass, the K+/Na+ ratio, and shoot B, sodium, and copper concentrations, but reduced root B concentrations and ion leakage. AMF inoculation slightly increased root dry weight and the sodium, potassium, zinc, copper and Mn contents in shoots under combined B and salinity stress, while AMF reduced the electrolyte leakage in leaves. It is inferred that AMF can ameliorate B toxicity in maize by improving biomass and reducing B concentration in plant tissues. Our research implies that C. etunicatum could be a valuable candidate for assisting in the remediation of boron-contaminated and saline soils.

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.

Rainfed lentil (lens culinaris Medik.) responses to manganese foliar spray when grown in a high-calcareous soil

This study was designed to evaluate the response of rainfed lentil to manganese (Mn) foliar application in high-calcareous soil located in the arid Mediterranean area. Field experiments on two clay calcareous soils containing different free carbonates and exchangeable Mn contents were carried out. The soil“1” has Mn content (DTPA extraction) of 7.5 mg kg −1 and it contains 8.9% of free carbonates. The soil“2” contains 3.3 mg kg −1 of Mn and it has a free carbonates level of 15.9%. Five foliar spray concentrations of Mn in lentil (0 as control; 0.5%; 1%; 3%; and 8%) were tested. Mn was applied in the sulfate form at flower bud and flowering. The soil“1” and soil”2” were evaluated during the 2016–17 and 2017–18 seasons, respectively. Results showed that foliar Mn feeding did not enhance grain yield and its components. Mn foliar spray over than 1% resulted in leaf damage during the rainfall season 2017–18 (429 mm) compared to 2016–17 (289 mm). At 8% of Mn, the phytotoxicity reduced grain yield by 34.5% compared to control. For both calcareous soils, shoot Mn content at the end of flowering was over 30 mg kg −1 for control and exceeded 1800 mg kg −1 at 8% of Mn. No antagonism or synergy between Mn and the other nutrients (N, P, K, Ca, Mg, Cu, and Zn) was recorded.

Alkalinized sewage sludge affects nutrition and growth of common bean cultivated in Ferralsols

A aplicação de lodo de esgoto alcalino em solos agrícolas aumentou, mas as implicações nutricionais para as culturas ainda são pouco exploradas. Com o objetivo de avaliar o efeito do lodo de esgoto alcalinizado na nutrição e crescimento do feijoeiro (Phaseolus vulgaris L.), foi realizado experimento em casa de vegetação com três Latossolos e três tipos de lodo de esgoto. Amostras de Latossolos (texturas franca, muito argilosa e argilosa) foram coletadas em três regiões geologicamente distintas do estado do Paraná, Brasil: arenito, basalto e argilito. Amostras de lodo de esgoto foram estabilizadas com calcário e posteriormente misturadas com as amostras de solo. Lodo de esgoto alcalinizado e calcário foram aplicados aos solos nas taxas correspondentes a 50, 100, 150 e 200% da quantidade necessária para o solo atingir pH 5,5. Aos 67 dias após emergência, foram medidas a altura das plantas, matéria seca da parte aérea e composição elementar das folhas. Em comparação ao calcário, o lodo alcalinizado promoveu maior produção de matéria seca da planta nos solos argilosos. O lodo de esgoto alcalinizado aplicado aos solos resultou em maiores teores de Zn e P na parte aérea da planta do que o calcário, enquanto ambos os corretivos reduziram os teores de K e Mn na parte aérea. A relação Fe/Mn mostrou ser muito efetivo para explicar sintomas foliares que foram observados sob condição de elevada acidez. O lodo alcalinizado apresentou desempenho superior quanto à nutrição e promoção do crescimento do feijoeiro no solo argiloso.

Excess Copper-Induced Changes in Antioxidative Enzyme Activity, Mineral Nutrient Uptake and Translocation in Sugarcane Seedlings.

Sugarcane is a potential species for use in heavy metal remediation. To analyze the effect of excess copper on sugarcane, the biomass, mineral nutrient content and activities of antioxidative enzymes were measured under copper stress. The results revealed that the biomass of roots and shoots significantly decreased with increasing copper concentration in solution. Most copper accumulated in the roots, and the translocation factor of copper decreased with an increase in copper stress. The MDA content in sugarcane roots notably increased under copper stress. The POD activity in sugarcane roots increased, and CAT activity decreased under copper stress. The Zn, Fe and Mn contents in shoots increased significantly under 200μmolL-1 Cu2+ treatments. The Zn and Mg contents in roots notably decreased under copper stress, while the Zn and Mg translocation factors increased. These results indicated that the increase in POD activity and the modification of mineral nutrient uptake and transfer might play an important role in reducing the detrimental effects of excess copper.

Metabolic changes induced by manganese in chamomile

Manganese (Mn) uptake and toxicity in chamomile (Matricaria chamomilla) and changes of phenolic metabolites in plants grown in the soil (1000 μM Mn2+) or hydroponic culture (100 or 1000 μM Mn2+) were studied. Under soil cultivation, Mn excess reduced growth and induced symptoms of oxidative stress (including total ROS, hydroxyl radical and lipid peroxidation as detected by fluorescence microscopy), concomitantly with depletion of non-protein thiols and ascorbic acid. Total soluble phenols and individual phenolic acids were rather depleted (p-coumaric, chlorogenic, and protocatechuic acids) or unaltered (vanillic and caffeic acids). Shoot Mn content reached 2806 μg/g DW with BAF 51.0 in the soil culture. In hydroponics, tetraploid plants contained less Mn in both shoots and roots than diploid ones with bioaccumulation factor and translocation factor (diploid/tetraploid) 57.1/37.9 and 0.39/0.32 in 1000 μM Mn treatment. Plants cultured in hydroponics revealed stimulation of some phenolic acids, mainly chlorogenic acid in the shoots and p-hydroxybenzoic and vanillic acids in the roots (more extensively in tetraploid ones which contained less Mn). Data indicate that excessive Mn accumulation has negative impact not only on the growth but also on phenolic metabolites in young plants mainly. Detailed comparison of the observed metabolic changes with limited literature focused on Mn physiology is provided as well.

Physiological and biochemical mechanisms preventing Cd-toxicity in the hyperaccumulator Atriplex halimus L.

The xero-halophyte Atriplex halimus L., recently described as Cd-hyperaccumulator, was examined to determine Cd toxicity threshold and the physiological mechanisms involved in Cd tolerance. An experiment was conducted to investigate the effect of cadmium from 0 to 1350 μM on chlorophyll fluorescence parameters, gas exchange, photosynthetic pigment concentrations and antioxidative enzyme activities of A. halimus. Cadmium, calcium, iron, manganese, magnesium, potassium, phosphorous, sodium and zinc concentrations were also analyzed. Plants of A. halimus were not able to survive at 1350 μM Cd and the upper tolerance limit was recorded at 650 μM Cd; although chlorosis was observed from 200 μM Cd. Cadmium accumulation increased with increase in Cd supply, reaching maxima of 0.77 and 4.65 mg g−1 dry weight in shoots and roots, respectively, at 650 μM Cd. Dry mass, shoot length, specific leaf area, relative growth rate, net photosynthetic rate, stomatal conductance, pigments contents and chlorophyll fluorescence were significantly reduced by increasing Cd concentration. However, the activities of superoxide dismutase (SOD; EC1.15.1.1), catalase (CAT; EC1.11.1.6) and guaiacol peroxidase (GPx; EC1.11.1.7) were significantly induced by Cd. Exposures to Cd caused also a significant decrease in P contents in roots, Mg and Mn contents in shoots and Fe and K contents in roots and shoots and had no effect on Ca, Na and Zn contents. The tolerance of A. halimus to Cd stress might be related with its capacity to avoid the translocation of great amounts of Cd in its aboveground tissues and higher activities of enzymatic antioxidants in the leaf.

Comparison of manganese tolerance and accumulation among 24 Salix clones in a hydroponic experiment: Application for phytoremediation

Willows (Salix spp.) are excellent candidates for phytoremediation owing to their large biomass, high metal tolerance and accumulation capacity. In this study, manganese tolerance and accumulation capability in 24 Salix clones were evaluated exposed to 1mM Mn by a hydroponic system for 21days. Results suggested that there were wide variations in Mn tolerance and accumulation capability among the clones. Clonal variation in biomass production ranged from growth reduction to growth stimulation. The clonal differences in Mn concentrations (μgg−1, dry weight, DW) ranged from 3183.10 to 5827.7 in leaves, from 1840.48 to 4572.17 in stems, and from 2733.33 to 10,253.88 in roots exposed to excess Mn. The total Mn contents in shoots (including leaves and stems) varied 5.8-fold among clones under Mn treatment. Five clones exhibited high Mn tolerance and accumulation capacity, and clone J333 (Salix babylonica×Salix matsudana) had a relatively high Mn tolerance index and the highest Mn content in aboveground tissues. Consequently, further evaluation of the Salix clones for Mn tolerance and phytoremediation potential is recommended in field experiments.

Toxicity of naturally-contaminated manganese soil to selected crops.

The impact of manganese excess using naturally contaminated soil (Mn-soil, pseudototal Mn 6494 vs 675 μg g(-1) DW in control soil) in the shoots of four crops was studied. Mn content decreased in the order Brassica napus > Hordeum vulgare > Zea mays > Triticum aestivum. Growth was strongly depressed just in Brassica (containing 13696 μg Mn g(-1) DW). Some essential metals (Zn, Fe) increased in Mn-cultured Brassica and Zea, while macronutrients (K, Ca, Mg) decreased in almost all species. Toxic metals (Ni and Cd) were rather elevated in Mn-soil. Microscopy of ROS, NO, lipid peroxidation, and thiols revealed stimulation in all Mn-cultured crops, but changes were less visible in Triticum, a species with low shoot Mn (2363 μg g(-1) DW). Antioxidative enzyme activities were typically enhanced in Mn-cultured plants. Soluble phenols increased in Brassica only while proteins rather decreased in response to Mn excess. Inorganic anions (chloride, sulfate, and phosphate) were less accumulated in almost all Mn-cultured crops, while the nitrate level rather increased. Organic anions (malate, citrate, oxalate, acetate, and formate) decreased or remained unaffected in response to Mn-soil culture in Brassica, Hordeum, and Triticum but not in Zea. However, the role of organic acids in Mn uptake in these species is not assumed. Because control and Mn-soil differed in pH (6.5 and 3.7), we further studied its impact on Mn uptake in solution culture (using Mn concentration ∼5 mM deducted from water-soluble fraction of Mn-soil). Shoot Mn contents in Mn-treated plants were similar to those observed in soil culture (high in Brassica and low in Triticum) and pH had negligible impact. Fluorescence indicator of "general ROS" revealed no extensive or pH-dependent impact either in control or Mn-cultured roots. Observed toxicity of Mn excess to common crops urges for selection of cultivars with higher tolerance.

Application of High Copper and Zinc Compost and Its Effects on Soil Properties and Growth of Barley

A compost of high copper (Cu) and zinc (Zn) content was added to soil, and the growth of barley (Hordeum vulgare L.) was evaluated. Four treatments were established, based on the addition of increasing quantities of compost (0, 2, 5, and 10% w/w). Germination, plant growth, biomass production, and element [nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), sodium (Na), magnesium (Mg), iron (Fe), Cu, manganese (Mn), and Zn] contents of soil and barley were determined following a 16‐week growing period. Following harvesting of the barley, analysis of the different mixtures of soil and compost was performed. Micronutrient contents in soils as affected by compost additions were determined with diethylene–triamine–pentaacetic acid (DTPA) (Cu, Mn, Fe, and Zn) or ammonium acetate [Ca, Na, Mg, K, cation exchange capacity (CEC)] extractions, and soils levels were compared to plant uptake where appropriate. Increasing rates of compost had no affect on Ca, Mg, or K concentration in barley. Levels of Cu, Zn, Mn, and Na, however, increased with compost application. High correlations were found for DTPA‐extractable Cu and Zn with barley head and shoot content and for Mn‐DTPA and shoot Mn content. Ammonium acetate–extractable Na was highly correlated with Na content in the shoot. High levels of electrical conductivity (EC), Cu, Zn, and Na may limit utilization of the compost.

Quantification of the confounding effect of seed manganese content in screening for manganese efficiency in durum wheat (triticum turgidum L. var. durum)

Whether due to the genotype or the environment of the mother plant, the nutrient content of seeds vary over a wide range; the amount of the nutrient contributes greatly to seedling vigor, especially on deficient soils and may result in major differences in grain yield. This effect has important implications for breeding programs. This paper examines the impact of seed manganese (Mn) on screening of durum wheats for tolerance to Mn‐deficient soils. Seed stocks with a range of Mn contents (0.4–2.4 μg seed‐1) were produced, and the effect on expression of Mn efficiency measured as either relative yield or shoot Mn content for two durum wheat (Triticum turgidum L. var. durum) genotypes differing in Mn efficiency. Both genotypes responded to seed Mn content in terms of enhanced root and shoot growth; there was no genotype by seed Mn interaction, so Mn provided in seed was utilized additively by both Mn‐efficient and Mn‐inefficient genotypes. Manganese efficiency, measured as relative yield, was a function of seed Mn content and varied from 40 to 70% in Hazar and 58 to 90% in Stojocri 2, in the same assay using seed of variable Mn content. From the response curves of yield vs. soil Mn added, the Mn required for 90% relative yield was determined for each level of seed Mn content. Seed Mn was regressed against the soil added Mn needed to obtain 90% of maximal growth at each level of seed Mn content (a total of 8 levels) for each of two genotypes. There was an inverse linear relationship between the amount of soil Mn and seed Mn needed for each genotype. Using the Mn‐efficient genotype with high seed Mn content, the soil Mn needed to obtain 90% growth was nil, while inefficient genotypes with low Mn content required 75 mg Mn kg‐1 soil to produce the same relative yield. This relationship can be used to adjust the levels of soil applied Mn to be used in a pot bioassay when seeds have a certain Mn content, so as to maintain the screening at an optimal overall level of Mn stress.

Effect of corncob compost on plant growth in an acid red soil

A comparison of corncob compost with lime on plant growth was studied in acid red soil with pH of 4.07. Lettuce, pea, and corn were selected as test plants for their varying tolerance to acid soil. The pot experiment compared six soil treatments and a check. Soil amendments were 1, 2, and 4 cmol calcium carbonate (CaCO3) kg‐1 and 5, 10, and 20 g corncob compost kg‐1 soil. Results showed higher manganese (Mn) than aluminum (Al) content of the shoot in all check group plants. Reduced shoot Mn content increased shoot dry weight in all test plants, regardless of acid soil tolerance or soil treatment. The higher the test plant resistance to soil acidity, the weaker the detoxification effect of corncob compost was on Al uptake when compared with the check group. Liming was more effective at reducing shoot Mn content than corncob compost with the exception of the more acidity sensitive lettuce. Shoot phosphorus (P) content, however, increased with corncob compost from enhanced organic matter rates. Corncob compost treatments significantly increased shoot dry weight over liming in the acid soil. This study demonstrated an environmentally acceptable use for an agricultural waste.

Effect of different levels of humic acids on nutrient content and growth of corn (Zea mays L.)

The effect of humic acids on nutrient uptake and growth of corn plants (Zea mays L.) was investigated by growing corn in plastic growth pouches containing a Hoagland nutrient solution to which were added 0, 320, 640, 1,600 or 3,200 ppm HA, pH 7.0. The experiments were carried out in three replicates for a growing period of 16 days after germination. Humic acid was in general beneficial to shoot and root growth of corn plants. Dry matter yield in corn shoots was stimulated by HA, especially by treatments with 640 ppm HA. Nutrient uptake showed a number of differences as a result of treatments with HA. Moderate applications with HA resulted in a significant increase in N content of corn shoots, while large amounts of HA had a tendency to reduce the N concentration in corn shoots. As a result of the HA treatments, P concentrations in corn shoots were decreased, but differences in K contents were statistically nonsignificant and Mn contents in shoots were also nonsignificantly different among the treatments. However, Zn content showed a tendency to increase with increasing applications of HA.