Plant Mn Uptake Research Articles

Enhancing Manganese Availability for Plants through Microbial Potential: A Sustainable Approach for Improving Soil Health and Food Security

Manganese (Mn) is essential for plant growth, as it serves as a cofactor for enzymes involved in photosynthesis, antioxidant synthesis, and defense against pathogens. It also plays a role in nutrient uptake, root growth, and soil microbial communities. However, the availability of Mn in the soil can be limited due to factors like soil pH, redox potential, organic matter content, and mineralogy. The excessive use of chemical fertilizers containing Mn can lead to negative consequences for soil and environmental health, such as soil and water pollution. Recent research highlights the significance of microbial interactions in enhancing Mn uptake in plants, offering a more environmentally friendly approach to address Mn deficiencies. Microbes employ various strategies, including pH reduction, organic acid production, and the promotion of root growth, to increase Mn bioavailability. They also produce siderophores, anti-pathogenic compounds, and form symbiotic relationships with plants, thereby facilitating Mn uptake, transport, and stimulating plant growth, while minimizing negative environmental impacts. This review explores the factors impacting the mobility of Mn in soil and plants, and highlights the problems caused by the scarcity of Mn in the soil and the use of chemical fertilizers, including the consequences. Furthermore, it investigates the potential of different soil microbes in addressing these challenges using environmentally friendly methods. This review suggests that microbial interactions could be a promising strategy for improving Mn uptake in plants, resulting in enhanced agricultural productivity and environmental sustainability. However, further research is needed to fully understand these interactions’ mechanisms and optimize their use in agricultural practices.

Mimosine facilitates Fe uptake by Leucaena leucocephala subsp. glabrata in alkaline soils by solubilizing Fe-oxides

PurposeGiant leucaena is a tropical tree-legume that thrives in alkaline and calcareous soils. It contains large amounts of mimosine, the physiological role of which is not well understood. The goals of this study were to determine i) if mimosine is released by giant leucaena into the rhizosphere ii) if mimosine enhances solubility of Fe present in various forms in alkaline soil, and iii) if mimosine enhances transition metal uptake in giant leucaena.MethodsMimosine in the extracts of rhizosphere soil and root exudates was analyzed by high performance liquid chromatography (HPLC) and liquid chromatography/mass spectrometry (LC/MS) to determine if it is released by giant leucaena. Iron concentration in tissue and aqueous samples was determined by ICP-OES analysis.ResultsMimosine was detected in both the rhizosphere eluates and root exudates. Mimosine added to samples of goethite, hematite and FeCl3 increased Fe solubility in water. Giant leucaena plants grown in alkaline soils and supplied with mimosine had higher levels of chlorophyll, Fe and Mn than the control plants.ConclusionMimosine is released by giant leucaena roots into the rhizosphere, where it interacts with Fe. Mimosine enhances solubility of insoluble Fe-oxides and prevents conversion of ferric Fe to insoluble oxides at an alkaline pH. Mimosine enhances Fe and Mn uptake in plants growing in alkaline soil conditions.

Manganese uptake by red maples in response to mineral dissolution rates in soil

Manganese (Mn) is an essential plant micronutrient that influences photosynthesis, ecosystem productivity, and soil carbon storage. Our objective was to quantify how Mn uptake by forest vegetation relates to Mn release into soil solution through mineral dissolution. A greenhouse pot experiment was conducted to quantify Mn uptake by red maple saplings as a function of mineral solubility to test whether Mn uptake was limited by the supply of Mn to soil solution. Differences in soil microbial community composition between treatments, particularly amongst Mn cycling bacteria and fungi, were also evaluated to assess potential microbial impacts on observed Mn fluxes. Plant Mn uptake was highest in systems supplied with dissolved Mn(II) because it was not kinetically limited by mineral weathering. Mn uptake was also higher in systems supplied with a fast-weathering substrate (shale containing Mn(II)-bearing pyrite) than a slow-weathering substrate (Mn(IV)-oxide). However, vegetation accumulated a decreasing proportion of available Mn with increasing solubility, indicating that uptake was tempered relative to solubility. The presence of bacterial phyla containing known Mn-oxidizing bacteria indicates the potential for Mn-oxidizing bacteria to influence Mn solubility within Mn-oxide and dissolved Mn treatments. A relatively low abundance of these bacteria points to their limited capacity to oxidize and retain Mn in the shale treatments, consistent with substantial Mn leaching. We conclude that Mn uptake was primarily controlled by dissolution rates of Mn-bearing minerals but modified by biological processes. The quantitative framework presented here can guide understanding of how biogeochemical processes control element cycling between plants and soils.

Severidade da mancha-marrom em trigo cultivado com diferentes formas de nitrogênio e doses de manganês

A fonte de N fornecido às culturas influencia algumas propriedades do solo como o pH, causando efeitos indiretos na disponibilidade e, consequentemente na absorção de nutrientes pela planta. Em relação ao Mn, que pode influenciar na susceptibilidade de plantas a doenças, pode haver alterações até mesmo nas relações patógeno-hospedeiro. O objetivo deste trabalho foi avaliar o efeito de duas fontes de N e cinco doses de Mn na severidade da mancha-marrom em plantas de trigo, bem como na produção de matéria seca da parte aérea e raízes, a absorção desses nutrientes pelas plantas e a disponibilidade do Mn no solo. O experimento foi instalado em casa de vegetação e os tratamentos dispostos em um esquema fatorial (2 × 5), sendo duas fontes de N (amoniacal e nítrica) e cinco doses de Mn (0; 2,5; 5,0; 10,0 e 20,0 mg dm-3), em delineamento de blocos casualizados, com quatro repetições. Foram utilizadas amostras de um Latossolo Vermelho distrófico em vasos contendo 2,2 dm³, com três plantas de trigo. Aos 45 dias após emergência (DAE), as plantas foram inoculadas com uma suspensão de 10(5) mL-1 conídios de Bipolaris sorokiniana. Foram determinados o grau de severidade final da mancha-marrom, a produção de matéria seca da parte aérea e das raízes, e os teores foliares de N e Mn nas plantas de trigo, assim como a disponibilidade de Mn no solo. Verificou-se efeito das fontes de N e das doses de Mn apenas na severidade da mancha-marrom e nos teores de Mn no solo e nas folhas. Houve respostas quadráticas para os teores de Mn no solo e nas folhas e para a severidade da mancha-marrom no trigo. A fonte amoniacal [(NH4)2SO4] proporcionou maior disponibilidade do Mn no solo do que a fonte nítrica [Ca(NO3)2], que foi acompanhada de aumento do teor foliar de Mn na planta e de diminuição da severidade da mancha-marron em trigo.

Manganese retention by selected calcareous soils as related to soil properties1

Calcareous soils often need supplemental manganese (Mn) to support optimum plant growth, but some reports show that the apparent recovery of applied Mn is very low in such soils, i.e., nearly all of the applied Mn is retained in the soil. This experiment was conducted to find the relationship between the retained Mn and selected properties of calcareous soils. Eleven surface (0–20 cm) soil samples with pH ranging from 7.7 to 8.1 and calcium carbonate equivalent (CCE) ranging from 20 to 50% were used in the Mn adsorption study. Two‐gram subsamples of each soil were equilibrated with 20 mL of 0.01M CaCl2 solutions initially containing 10 to 200 mg Mn L‐1. The Mn that disappeared from solution (after 6 h shaking at 25°C) was considered as adsorbed (retained) Mn. The adsorption data showed a highly significant fit to Freundlich and also to the two‐surface Langmuir adsorption isotherms. The coefficients of both isotherms showed significant positive correlations with cation exchange capacity (CEC), organic matter (OM), and CCE of the soils indicating that OM and calcium carbonate are the sites of Mn retention in calcareous soils. Comparison of the adsorption data of this experiment with those of plant Mn uptake of the same soils (published earlier) shows that as the Langmuir second surface adsorption maxima (maximum retention capacity) of the soils increase the plant Mn concentration and uptake decrease.

Interaction Between High Levels of Applied Heavy Metals and Indigenous Soil Manganese

AbstractThe importance of indigenous soil Mn level on plant Mn uptake from metal salt or sewage sludge amended soils was investigated. Twelve soil materials, six surface and six subsurface, were amended with either varying rates of a composite of Cd, Cu, Ni, and Zn sulfate salts, equivalent to the total of these metals present in a digested sewage sludge (Washington, D.C.) at rates of 0–896 dry metric tons/ha or with the sludge itself, at 224 dry metric tons/ha. Corn (Zea mays L.) was grown in the greenhouse for 30 days, 1 year after amendment application. Two pH levels of about 5.5 and 6.5 were maintained during the experiment on the metal salt amended soil materials.Plant tissue Mn levels increased with the application of Cd, Cu, Ni, and Zn (in combination) as metal salts or as sewage sludge over the range of soil materials used. The amount of increase with a given increase in applied metals was greater for the unlimed than for the limed metal salt treatments. Elevated tissue Mn concentrations were positively and significantly correlated with the indigenous levels of soil Mn. A tissue Mn level of over 3,000 µg/g was observed with unlimed metal salts equivalent to 896 dry metric tons/ha of sludge with Manor Ap horizon soil material. Studies by others suggest that elevation of tissue Mn levels may be related to replacement of Mn from Mn “oxides” by the applied heavy metals.The interaction between applied heavy metals and indigenous soil Mn may affect guidelines for disposition of metal‐bearing wastes on soils. Soils regarded as acceptable for waste disposition, but which have high native Mn levels, may produce higher plant tissue Mn levels than similar soils with lower native Mn.