Manganese Stress Research Articles

Investigation of the manganese stress on wheat plant by attenuated total reflectance Fourier transform infrared spectroscopy

ABSTRACTThe present paper deals with the investigation of the changes in chemical contents of the leaf of wheat seedling stressed by excess manganese using attenuated total reflectance Fourier transform infrared spectroscopy (FTIR) technique. The infrared spectra of the leaves of control and manganese-treated wheat plants have been recorded in the spectral region 485–4000 cm−1 at a resolution of 4 cm−1. The recorded spectrum has been analyzed with the help of curve-fitting method for the quantitative estimation of chemical contents and conformational changes. The study indicated changes arising in the polysaccharide, lignin, amino acid, secondary structure of protein, and lipid in the leaves of control and manganese-treated wheat plants. Manganese treatment increased the amount of cellulose, lignin, and amide II till 200 μM concentration, while a decrease was observed at 1000 µM concentration. Manganese induced conformational changes in the secondary structure of protein which was indicated by shifting of the bands to the higher wavenumber and change in the β sheet/α helix ratio. In addition, manganese stress decreased lipid content in the leaves of the wheat seedlings. The study demonstrates the potential of attenuated total reflectance FTIR for the non-invasive and rapid monitoring of the plants stressed with heavy metals.

Humic acids protective activity against manganese induced LTR (long terminal repeat) retrotransposon polymorphism and genomic instability effects in Zea mays

Long terminal repeat (LTR) retrotransposon polymorphism and genomic instability are considered to be one of the most important rearranging mechanisms under environmental stress. Triggering of this knowledge, we aimed to elucidate protective effect of humic acid (HA) on genomic instability and LTR retrotransposon polymorphism in Zea mays seeds subjected to manganese stress. REMAP (Retrotransposon-microsatellite Amplified Polymorphism) and IRAP (Inter-Retrotransposon Amplified Polymorphism) were used to define the GTS (Genomic Template Stability) levels and retrotransposon polymorphism. The results showed that all concentration used Mn led to an increase in retrotransposon polymorphism and DNA damage a reduction GTS rate showing the DNA damage. However, the treatments of humic acid (10%) together with Mn resulted as decreasing DNA damage and retrotransposon polymorphism and also increasing GTS. It can be suggested that HA applications removes the negative effects of Mn on retrotransposon polymorphism and GTS, when considering the research results.

Biochemical and ecophysiological responses to manganese stress by ectomycorrhizal fungus Pisolithus tinctorius and in association with Eucalyptus grandis.

At relatively low concentrations, the element manganese (Mn) is essential for plant metabolism, especially for photosynthesis and as an enzyme antioxidant cofactor. However, industrial and agricultural activities have greatly increased Mn concentrations, and thereby contamination, in soils. We tested whether and how growth of Pisolithus tinctorius is influenced by Mn and glucose and compare the activities of oxidative stress enzymes as biochemical markers of Mn stress. We also compared nutrient accumulation, ecophysiology, and biochemical responses in Eucalyptus grandis which had been colonized by the ectomycorrhizal Pisolithus tinctorius with those which had not, when both were exposed to increasing Mn concentrations. In vitro experiments comprised six concentrations of Mn in three concentrations of glucose. In vivo experiments used plants colonized by Pisolithus tinctorius, or not colonized, grown with three concentrations of Mn (0, 200, and 1000μM). We found that fungal growth and glucose concentration were correlated, but these were not influenced by Mn levels in the medium. The anti-oxidative enzymes catalase and glutathione S-transferase were both activated when the fungus was exposed to Mn. Also, mycorrhizal plants grew more and faster than non-mycorrhizal plants, whatever Mn exposure. Photosynthesis rate, intrinsic water use efficiency, and carboxylation efficiency were all inversely correlated with Mn concentration. Thus, we originally show that the ectomycorrhizal fungus provides protection for its host plants against varying and potentially toxic concentrations of Mn.

Genome-wide identification and expression profiling of the copper transporter gene family in Populus trichocarpa

Copper transporters (COPT/Ctr) have important roles in the transport of copper (Cu) across the cell membrane in many different species. A comprehensive phylogeny and a molecular structure analysis of the COPT/Ctr family in plants and animals are presented, with an emphasis and bioinformatic analysis of the copper transporter family in Populus trichocarpa (PtCOPT). Structural analyses of PtCOPTs showed that most have 3 transmembrane domains (TMDs), with an exception of PtCOPT4 (2 TMDs). Gene structure, gene chromosomal location, and synteny analyses of PtCOPTs demonstrated that tandem and segmental duplications have likely contributed to the expansion and evolution of the PtCOPTs. Additionally, promoter analyses showed that the function of PtCOPTs is related to Cu and ferrum (Fe) transport. Tissue-specific expression of PtCOPT genes showed that most had relatively high transcript levels in roots and leaves. Quantitative real-time RT-PCR (qRT-PCR) analysis revealed that the expression of PtCOPT genes were induced not only in limited and excessive Cu, Fe, zinc (Zn) and manganese (Mn) stress, but also in lead (Pb), and cadmium (Cd) stress.

The effect of choline-stabilized orthosilicic acid on microelements and silicon concentration, photosynthesis activity and yield of tomato grown under Mn stress

The aim of experiments was to assess the efficiency of choline-stabilized orthosilicic acid (ch-OSA; complex of orthosilicic acid with choline and a bioavailable source of silicon) application under increasing manganese (Mn) stress on the micronutritional composition and yielding of tomato (Solanum lycopersicum L. cvs. ‘Alboney F1’ and ‘Emotion F1’). Plants were grown in rockwool with the application of a nutrient solution varied the Mn concentrations (in mg dm−3): 9.6 and 19.2 which cause strong oxidative stress of plants comparing with optimal concentration of that microelement in nutrient solution. The effect of ch-OSA application (at Si concentration of 0.3 mg dm−3 nutrient solution) was investigated at both Mn-levels. Increasing Mn stress modified the concentration of microelements and silicon (Si) in tomato leaves. Application of ch-OSA also influenced the concentration of nutrients, but the determined changes were generally multidirectional and varied depending on Mn-level and cultivar. Under the increasing Mn stress a significant downward trend was observed for the mean concentration of Fe (in both cultivars) in fruits – but changes of Mn, Zn and Cu were varied depend on cultivar. In the case of cv. ‘Alboney F1’ ch-OSA application caused an increase the mean concentrations of Fe, Zn and Cu, while in the case of cv. ‘Emotion F1’ the reduction of mean concentrations of Zn and Cu was recorded. Ch-OSA treatment did not influence on the Mn concentrations in fruits. A beneficial role of ch-OSA was also found in photosynthesis activity. This was especially valid for lower levels of Mn. Application of ch-OSA improved significantly the marketable yield of tomato under stress by a low Mn level.

A Mur regulator protein in the extremophilic bacterium Deinococcus radiodurans.

Ferric uptake regulator (Fur) is a transcriptional regulator that controls the expression of genes involved in the uptake of iron and manganese, as well as vital nutrients, and is essential for intracellular redox cycling. We identified a unique Fur homolog (DR0865) from Deinococcus radiodurans, which is known for its extreme resistance to radiation and oxidants. A dr0865 mutant (Mt-0865) showed a higher sensitivity to manganese stress, hydrogen peroxide, gamma irradiation and ultraviolet (UV) irradiation than the wild-type R1 strain. Cellular manganese (Mn) ion (Mn2+) analysis showed that Mn2+, copper (Cu2+), and ferric (Fe3+) ions accumulated significantly in the mutant, which suggests that the dr0865 gene is not only involved in the regulation of Mn2+ homeostasis, but also affects the uptake of other ions. In addition, transcriptome profiles under MnCl2 stress showed that the expression of many genes involved in Mn metabolism was significantly different in the wild-type R1 and DR0865 mutant (Mt-0865). Furthermore, we found that the dr0865 gene serves as a positive regulator of the manganese efflux pump gene mntE (dr1236), and as a negative regulator of Mn ABC transporter genes, such as dr2283, dr2284 and dr2523. Therefore, it plays an important role in maintaining the homoeostasis of intracellular Mn (II), and also other Mn2+, zinc (Zn2+) and Cu2+ ions. Based on its role in manganese homeostasis, DR0865 likely belongs to the Mur sub-family of Fur homolog.

Genotypic variation in partitioning of dry matter and manganese between source and sink organs of rice under manganese stress.

Genetic variability in dry matter and manganese partitioning between source and sink organs was the key mechanism for Mn efficient rice genotypes to cope with Mn stress. Considerable differences exist among cereal genotypes to cope manganese (Mn) deficiency, but the underlying mechanisms are poorly understood. Minimal information regarding partitioning and/or remobilization of dry matter and Mn between source and sink organs exists in rice genotypes differing in Mn efficiency. The present study was aimed to assess the growth dynamics in terms of dry matter and Mn remobilization in the whole plant (leaves and tillers as source and panicles and grains as sink) during the grain development in diverse rice genotypes. The efficient genotypes accumulated higher dry matter than inefficient genotypes under low Mn level. The translocation index i.e., uptake in grain/total uptake was 0.11 in efficient genotype (PR 116) and 0.04 in inefficient genotypes (PR 111). The efficient genotype had higher grain Mn utilization efficiency of 0.71 in comparison to 0.48 of inefficient genotype indicating that in efficient genotype, Mn in grain produces more dry matter than inefficient genotypes. The efficient genotypes also had higher flag leaf area and nitrate reductase activity. The source of efficient genotypes contributed to a greater extent to developing sink but further mobilization to grain was hindered by panicle. The panicle of inefficient genotypes had higher per cent of Mn uptake than efficient genotypes indicating that Mn was least mobilized from panicle to grain in inefficient genotypes. The lower per cent uptake of Mn in efficient genotypes indicated that Mn was mobilized from panicle to developing grain and this led to higher Mn translocation index in grain of efficient genotypes. The uptake partitioning revealed that source of all genotypes mobilized the Mn towards the sink to almost same extent but it was the panicle where highest per cent uptake per plant was in inefficient genotypes and lowest in efficient genotypes. The lowest per cent uptake in panicle of efficient genotypes revealed that it supported developing grain to have highest translocation index.

Evolutionary engineering and transcriptomic analysis of nickel-resistantSaccharomyces cerevisiae

Increased exposure to nickel compounds and alloys due to industrial development has resulted in nickel pollution and many pathological effects on human health. However, there is very limited information about nickel response, transport, and tolerance in eukaryotes. To investigate nickel resistance in the model eukaryote Saccharomyces cerevisiae, evolutionary engineering by batch selection under gradually increasing nickel stress levels was performed. Nickel hyper-resistant mutants that could resist up to 5.3 mM NiCl2 , a lethal level for the reference strain, were selected. The mutants were also cross-resistant against iron, cobalt, zinc, and manganese stresses and accumulated more than twofold higher nickel than the reference strain. Global transcriptomic analysis revealed that 640 upregulated genes were related to iron homeostasis, stress response, and oxidative damage, implying that nickel resistance may share common mechanisms with iron and cobalt resistance, general stress response, and oxidative damage.

Populus cathayana males are less affected than females by excess manganese: Comparative proteomic and physiological analyses

The comprehension of sexually different responses in dioecious plants to excess manganese (Mn) stress requires molecular explanation. Physiological and proteomic changes in leaves of Populus cathayana males and females were analyzed after 4 wk of exposure to Mn stress. Under excess Mn conditions, shoot height and photosynthesis decreased more in females than in males. Females also showed severe browning and subcellular damage, higher Mn2+ absorption, and different antioxidant enzyme activities compared with males. There were ten differently regulated protein spots induced by excess Mn stress. They were mainly related to photosynthesis, ROS cleaning, and cell signaling associated to ROS, plant cell death, heat shock, cell defense and rescue, and gene expression and regulation. Variation in protein expression between the sexes clearly showed that males have evolved more efficient photosynthesis capacity, more stable gene expression and regulation, and better cell defense and rescue to prevent further injury under excess Mn stress.

Subcellular Mn compartation, anatomic and biochemical changes of two grape varieties in response to excess manganese

To explore the underlying mechanism for the high tolerance to excess manganese stress in the grape species (Vitis vinifera Linn), we observed the subcellular compartment of Mn element, anatomic and biochemical responses of two grape cultivars (Combier and Shuijin) under excess Mn stress in semi-controlled environmental condition. Grape species exhibited typical detoxifying or tolerant mechanism as following: first, majority of Mn element accumulated in leaf was excluded into cell wall or comparted into cell vacuole to avoid cellular Mn-toxicity; Mn and other elements were also secreted into leaf surface or deposited in vascular wall; second, only small amount of Mn was located in cellular organ, and excess Mn in chloroplast was detoxified by depositing in starch granule, which serve as a novel detoxifying strategy; additionally, the cellular Mn was further chelated by phytochelatins; third, to quench the toxic oxygen radicals, the total phenolic compounds and polyamine (putrescine and spermidine) were enhanced. Although the obvious symptom of Mn-toxicity was not detected, we observed the dessication symptom under high level of Mn treatment in the two cultivars, such as sunk stomata, thickened palisade tissue, enhanced palisade/spongy tissue ratio and abscisic acid concentration. The growth inhibition and dessication symptom in the two grape cultivars could be largely associated with osmotic stress resulted from high concentration of leaf Mn.

Temporal changes of polyphenols and enzyme activities in seedlings of Kandelia obovata under lead and manganese stresses

The temporal responses of peroxidase (POD), superoxide dismutase (SOD), total polyphenols (TP), extractable condensed tannins (ECT) to different levels of lead (Pb) or manganese (Mn) stress, as well as the metal accumulation, in seedlings of Kandelia obovata were investigated. Both stress time and stress intensity had significant effects with significant accumulation of Pb and Mn in roots at Day 1. Pb and Mn showed no significant effects on root or leaf TP and ECT at Day 1. Prolonged exposure to metals caused significant drops of root TP and ECT but increased in leaves at Days 7 and 49. POD activities decreased in both roots and leaves at Day 1, while POD and SOD both increased under moderate levels of Pb and Mn at Day 7. The present study showed that antioxidative enzyme activities were more sensitive indicators to Pb or Mn stresses than phenolic compounds.

Manganese homeostasis in Saccharomyces cerevisiae.

Manganese homeostasis in Saccharomyces cerevisiae.

Changes in anatomy and root cell ultrastructure of soybean genotypes under manganese stress

The deleterious effects of both Mn deficiency and excess on the development of plants have been evaluated with regard to aspects of shoot anatomy, ultrastructure and biochemistry, focusing mainly on the manifestation of visual symptoms. However, there is little information in the literature on changes in the root system in response to Mn supply. The objective of this study was to evaluate the effects of Mn doses (0.5, 2.0 and 200.0 μmol L-1) in a nutrient solution on the anatomy of leaves and roots of the Glycine max (L.) cultivars Santa Rosa, IAC-15 and IAC-Foscarin 31. Visual deficiency symptoms were first observed in Santa Rosa and IAC-15, which were also the only cultivars where Mn-toxicity symptoms were observed. Only in IAC-15, a high Mn supply led to root diameter thickening, but without alteration in cells of the bark, epidermis, exodermis and endodermis. The degree of disorganization of the xylem vessels, in particular the metaxylem, differed in the cultivars. Quantity and shape of the palisade parenchyma cells were influenced by both Mn deficiency and toxicity. A reduction in the number of chloroplasts was observed in the three Mn-deficient genotypes. The anatomical alterations in IAC-15 due to nutritional stress were greater, as expressed in extensive root cell cytoplasm disorganization and increased vacuolation at high Mn doses. The degree of changes in the anatomical and ultrastructural organization of roots and leaves of the soybean genotypes studied differed, suggesting the existence of tolerance mechanisms to different intensities of Mn deficiency or excess.

Role of the manganese efflux system mntE for signalling and pathogenesis in Streptococcus pneumoniae

The ability of bacteria to sense and respond to both environmental and intracellular metal concentrations plays an important role in pathogenesis. The acquisition of manganese is vital for the virulence of several bacterial species. Although manganese uptake systems have been well studied in bacteria, no manganese efflux system has yet been identified. In this study we have identified a cation diffusion facilitator (CDF) protein (Sp1552) of unknown substrate specificity that functions as a manganese export system in Streptococcus pneumoniae. We designated the gene for this manganese efflux system mntE and found that the mutant strain was highly sensitive to manganese stress. Although the mutant was more resistant to oxidative stress and produced more H(2)O(2) and pili, it had reduced virulence in a murine model of infection, indicating that manganese export plays a role in host pathogenesis. There was a distinct differential transcriptional response to extracellular and intracellular manganese accumulation. Our study indicates that manganese efflux is required for invasive disease and may provide a useful antimicrobial target to devise future therapeutics.

Characterization of manganese use efficiency in UK wheat cultivars grown in a solution culture system and in the field

The aim of the research was to describe and characterize the physiological basis of Mn use efficiency among a range of old and modern UK wheat cultivars grown in Mn-depleted solution culture and to ascertain whether the existence of Mn use efficiency conferred a yield advantage under manganese stress conditions in the field. Results of solution culture experiments demonstrated that the old spring wheat cv. Maris Butler is relatively Mn efficient when grown in Mn-deficient conditions in comparison with both a modern winter wheat, cv. Claire, and a modern spring wheat, cv. Paragon. The mean dry weight gain of plants of cv. Maris Butler grown in Mn-depleted nutrient solution was 0·49 of that shown by plants in Mn-sufficient culture, whereas in cvs. Paragon and Claire the equivalent values were 0·38 and 0·21 respectively. When grown in Mn-deficient soil in a farm-based field trial, cv. Maris Butler showed significantly improved (P<0·05) dry matter accumulation and grain yield compared with other spring wheats including cv. Paragon. There was no significant variation in leaf Mn content between the cultivars examined, either under sufficient or depleted Mn supply; however, cv. Maris Butler showed both a relatively high maximum light-saturated rate of photosynthesis and a high photosynthetic apparent quantum yield (based on O2 evolution) when grown under Mn deficiency. It is argued that the apparent Mn use efficiency of cv. Maris Butler is related to superior internal utilization of Mn, resulting in an increased photosynthetic photosytem II efficiency rather than improved Mn uptake and accumulation. The results suggest that the wheat cultivar Maris Butler may provide a potentially useful source of parental material for future crop improvement programmes designed to produce wheat lines resistant to depleted Mn supply.

Metal-free cultivation of Glomus sp. BEG 140 isolated from Mn-contaminated soil reduces tolerance to Mn.

The ability of arbuscular mycorrhizal (AM) fungi of different origin and cultivation history to tolerate excessive levels of manganese (Mn) was studied using hydroponic sand culture. Maize plants were colonised with two lineages of Glomus sp. BEG 140 from Mn-contaminated soil kept for 2 years in metal-free substrate or in the original soil. For comparison, the plants were also inoculated with Glomus intraradices BEG 75 from uncontaminated soil or were left uncolonised. Manganese stress was simulated by irrigation with nutrient solutions containing Mn at high concentrations (0.1, 0.5 and 1 mM); control plants were supplied with 3.8 microM Mn. Whereas the growth of maize plants was not suppressed by Mn at the concentrations examined, the development of AM fungi was negatively influenced by the higher Mn concentrations, with significant differences between isolates and cultivation lineages. The isolate Glomus sp. from Mn-contaminated soil showed higher tolerance to Mn than G. intraradices from uncontaminated soil. Colonisation by G. intraradices was reduced by almost 90% when irrigated with 1 mM Mn, whereas colonisation by the Glomus sp. lineage kept in contaminated soil still reached high levels (65% of the colonisation level of the control plants). The lineage of Glomus sp. cultured in inert metal-free substrate tolerated excessive Mn levels to a lesser extent than the lineage kept long-term in the original contaminated soil, but withstood Mn at higher concentrations than the G. intraradices from uncontaminated soil.

Accumulation of amino acids, proline, and carbohydrates in response to aluminum and manganese stress in maize

Synthesis of amino acids, proline, and carbohydrates was studied in roots and shoots of 5 maize accessions, differing in aluminum (Al) and manganese (Mn) tolerance, in response to Al and Mn stress at the seedling stage in solution culture. The concentrations of these metabolites increased in roots and shoots of the seedlings in the nutrient solution with added Al (0.22 mM), and Mn (2.0 mM). Both Al and/or Mn tolerant and non‐tolerant accessions accumulated more metabolites under stress than control. Generally, the tolerant accessions accumulated more solutes than the non‐tolerant maize accessions examined.

Differential genotypic tolerance response to manganese stress in triticale

Manganese (Mn) tolerance response in two aluminum (Al)‐tolerant triticale (× Triticosecale Wittmack) varieties was characterized by measurements of growth and dry matter production of seedlings in nutrient solution culture containing 100 mg L‐1 Mn. Root weight index (RWI) and total weight index (TWI) based on relative plant growth were two indicators of differentiating genotypic Mn tolerance; these two indices were used to make a comparative assessment of the degree of Mn tolerance in a group of eight Australian and South African genotypes which differ in apparent Al tolerance. The G4–95A was more Mn‐tolerant than its Al‐tolerant counterpart Tahara. A wide range of Mn tolerance was found in the eight genotypes, but few were tolerant of both Al and Mn stresses; measurements of RWI at 100 mg L‐1 Mn stress differentiated them into three response types (i.e., Mn‐tolerant, moderately Mn‐tolerant/Mn‐sensitive, and Mn‐sensitive) at the two critical values of 0.30 and 0.60. Covariation analysis indicated no association between Mn tolerance and Al tolerance; selective breeding for acidic stress tolerance should focus on both stress tolerances.

Cytological and ultrastructural response of Nicotiana tabacum L. roots to manganese stress

ABSTRACT The effects of manganese on the morphology and ultrastructure of root cells were studied in in vitro selected plantlets tolerant to high concentrations (5 mM) of Mn which, in a previous investigation, had shown a significant reduction in root growth when compared to the control (0.1 mM Mn). A decrease in the length of the root cap and meristematic region was observed. The most serious effects of Mn toxicity occurred in the outer root cap and outer meristematic cells where extensive cytoplasmic disorganisation was observed. The plasma membrane, in particular, displayed ruptures associated with the formation of vesicular and multi-lamellar bodies. Mitochondria also revealed strong structural alterations. However, the cells in the inner regions of the meristem showed better preserved subcellular components and exhibited normal mitotic activity. These last conditions suggest a possible resistance strategy which permits root development to continue. The primary root structure was not affected by the metal, except the central cylinder where 5 mM Mn induced precocious xylem differentiation (protoxylem and metaxylem), while in the corresponding zone control roots showed protoxylem elements only. Moreover, the epidermis-esoderm cell morphology seemed to be influenced by the metal.

Effect of metal stress on the thermal infrared emission of soybeans: A greenhouse experiment: Possible utility in remote sensing

Manganese-sensitive forest and manganese-tolerant lee soybean cultivars were subjected to differential manganese stress in loring soil in a greenhouse experiment. Leaf temperature measurements were made using thermistors for forest and lee. Manganese-stressed plants had higher leaf temperatures than control plants in both forest and lee. Results of this experiment have potential applications in metal stress detection using remote sensing thermal infrared data over large areas of vegetation. This technique can be useful in reconnaissance mineral exploration in densely-vegetated regions where conventional ground-based methods are of little help.