Transport Of Mineral Nutrients Research Articles

In situ mapping of ion distribution profiles and gene expression reveals interactions between hypoxia and Mn2+/Fe2+ availability in barley roots

Flooding stress affects soil properties thus altering the availability, uptake, and transport of mineral nutrients in plant roots. Flooding stress also increases the amount of soluble Mn2+ and Fe2+ in the soil and their uptake by plants, causing elemental toxicity. However, as oxygen profiles in plant roots are not uniform, it is still unclear how soil flooding will affect Mn2+/Fe2+ absorption and distribution in different cell types and tissues. In this study, waterlogging sensitive barley variety NasoNijo (NN) and tolerant variety TX9425 (TX) were exposed to hypoxia, metal (Mn2+ and Fe2+), and combined hypoxia + metal treatment to map the in situ ion profiles at different regions of barley root. We found that combined hypoxia and metal stress causes significantly more reduction in plant biomass compared with the single submergence or metal stress. Despite this, more Fe and Mn were accumulated under metal stress condition than those under combined stress, regardless of variety. Cultivar NN absorbed more Fe and Mn than TX in the cortical cells of the root meristem and in the mature zone under metal stress which was also verified by histochemical detection. In the mature zone, the expressions of Fe and Mn transporter genes including HvADPRibase-Mn (Manganese-dependent ADP-ribose), HvZIP1 (zinc-regulated transporter /Fe-regulated transporter-like protein 1), HvYS1 (yellow stripe 1), HvNRAMP5 (Natural Resistance-Associated Macrophage Protein 5) were significantly downregulated under all three treatments in both barley varieties except HvADPRibase-Mn HvZIP1 cortex of TX were unchanged under metal stress. Interestingly, the transcripts of HvMTP1 (metal tolerance protein 1) were significantly downregulated by metal and combined stress in stele and upregulated by hypoxia and metal stress in cortex of TX, but not affected in NN. It is concluded that Fe and Mn absorption involving HvMTP1is associated with the extent of waterlogging tolerance in barley.

Endodermal apoplastic barriers are linked to osmotic tolerance in meso-xerophytic grass Elymus sibiricus.

Drought is the most serious adversity faced by agriculture and animal husbandry industries. One strategy that plants use to adapt to water deficits is modifying the root growth and architecture. Root endodermis has cell walls reinforced with apoplastic barriers formed by the Casparian strip (CS) and suberin lamellae (SL) deposits, regulates radial nutrient transport and protects the vascular cylinder from abiotic threats. Elymus sibiricus is an economically important meso-xerophytic forage grass, characterized by high nutritional quality and strong environmental adaptability. The purpose of this study was to evaluate the drought tolerance of E. sibiricus genotypes and investigate the root structural adaptation mechanism of drought-tolerant genotypes’ responding to drought. Specifically, a drought tolerant (DT) and drought sensitive (DS) genotype were screened out from 52 E. sibiricus genotypes. DT showed less apoplastic bypass flow of water and solutes than DS under control conditions, as determined with a hydraulic conductivity measurement system and an apoplastic fluorescent tracer, specifically PTS trisodium-8-hydroxy-1,3,6-pyrenetrisulphonic acid (PTS). In addition, DT accumulated less Na, Mg, Mn, and Zn and more Ni, Cu, and Al than DS, regardless of osmotic stress. Further study showed more suberin deposition in DT than in DS, which could be induced by osmotic stress in both. Accordingly, the CS and SL were deposited closer to the root tip in DT than in DS. However, osmotic stress induced their deposition closer to the root tips in DS, while likely increasing the thickness of the CS and SL in DT. The stronger and earlier formation of endodermal barriers may determine the radial transport pathways of water and solutes, and contribute to balance growth and drought response in E. sibiricus. These results could help us better understand how altered endodermal apoplastic barriers in roots regulate water and mineral nutrient transport in plants that have adapted to drought environments. Moreover, the current findings will aid in improving future breeding programs to develop drought-tolerant grass or crop cultivars.

Chalcogens reduce grain Cd accumulation by enhancing Cd root efflux and upper organ retention in wheat (Triticum aestivum L.)

A seedling-stage sand culture experiment and whole growth period pot experiment were conducted together to investigate the effects of chalcogenide elements (S, Se, Te) on the morphology, photosynthesis, Cd absorption, Cd and mineral nutrient transport, and transporter gene expression of wheat under Cd stress. Compared with S, Se and Te can alleviate wheat Cd toxicity and reduce Cd accumulation more efficiently. Compared with control conditions, S reduced the root Cd concentration by about 20 %, while SeIV and TeIV reduced the root Cd concentration by more than 60 % and the shoot Cd concentration by about 30 %. Chalcogens reduced Cd uptake by increasing root diameter (by about 50 %) and inhibiting lateral root formation under SeIV and TeIV treatments compared to Cd treatment alone. Moreover, chalcogens accelerated Cd efflux by up-regulating TaTM20 , thereby reducing Cd accumulation. Meanwhile, chalcogens enhanced Cd isolation in the cell wall and vacuole, reduced the active Cd proportion by increasing synthesis of chelates, and improved wheat Cd tolerance. Spraying Se and Te increased both the photosynthetic rate and yield, while also improving mineral nutrient contents (including magnesium, calcium, zinc, iron, manganese, copper, and molybdenum contents) in wheat grains. Selenomethionine (SeMet) was more effective in reducing upper organ Cd reactivation and inhibiting Cd transport from upper organs to grains, which was able to reduce grain Cd content by 27 % in the 5 mg/kg Cd treatment. Additionally, SeIV and TeIV reduced grain Cd content by 14 % and 16 %, respectively; while SeVI increased Cd content by 11 %. The current study reveals the mechanism by which chalcogens alleviate Cd toxicity and reduce grain Cd accumulation, which provides valuable insights for safe wheat production despite Cd soil contamination. • Se and Te alleviate Cd toxicity and increase wheat yield. • Chalcogens decrease Cd uptake by increasing root diameter and inhibiting lateral root growth. • Chalcogens reduce Cd accumulation by increasing root Cd efflux. • Increases in PC S -Cd complexes and up-regulation of HMA2 expression promote Cd transport to shoots. • SeMet reduces Cd transport to grains by reducing Cd reactivation in stem, leaf, and glume tissues.

Silicon-induced mitigation of drought stress in peanut genotypes (Arachis hypogaea L.) through ion homeostasis, modulations of antioxidative defense system, and metabolic regulations

Drought stress considered as a major environmental constraint that frequently limits crop production globally. In the current investigation, drought stress-induced alterations in growth, ion homeostasis, photosynthetic pigments, organic osmolytes, reactive oxygen species (ROS) generation, antioxidative components, and metabolic profile were examined in order to assess the role of silicon (Si) in mitigation of drought effects and to understand the drought adaptive mechanism in two contrasting peanut genotypes (GG7: fast growing and tall, TG26: slow growing and semi-dwarf). Si application significantly improved the leaf chlorophyll content, relative water content % (RWC %), growth and biomass in GG7 compared with TG26 genotype under water stress. Si supplementation considerably promotes the uptake and transport of mineral nutrients under drought condition in both the genotypes, which eventually promote plant growth. Exogenous application of Si protects the photosynthetic pigments from oxidative damage by reducing membrane lipid peroxidation and either maintained or reduced H2O2 accumulation in both the genotypes. The activity of enzymatic antioxidants like superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (GPX), and glutathione reductase (GR) and non-enzymatic antioxidants like ascorbate (AsA) and glutathione (GSH) were either maintained or increased in both the genotypes in response to Si under drought as compared to those without Si. Silicon-induced higher accumulation of metabolites mainly sugars and sugar alcohols (talose, mannose, fructose, sucrose, cellobiose, trehalose, pinitol, and myo-inositol), amino acids (glutamic acid, serine, histidine, threonine, tyrosine, valine, isoleucine, and leucine) in GG7 genotype as compared to TG26, provides osmo-protection. Moreover, Si application increased phytohormones levels such as indole-3-acetic acid (IAA), gibberellic acid (GA3), jasmonic acid (JA), and zeatin in GG7 genotype under drought stress compared to non-Si treated seedlings suggesting its involvement in signaling pathways for drought adaptation and tolerance. Noteworthy increment in polyphenols (chlorogenic acid, caffeic acid, ellagic acid, rosmarinic acid, quercetin, coumarin, naringenin, and kaempferol) in the Si treated seedlings of GG7 genotype as compared to TG26 under drought stress suggests an efficient mechanism of ROS sequestration in GG7 genotype. Our findings provide comprehensive information on physiological, biochemical, and metabolic dynamics associated with Si-mediated water stress tolerance in peanut. This study indicates that the drought tolerance efficacy of peanut genotypes can be improved by Si application.

Phylogenetic Diversity and Physiological Roles of Plant Monovalent Cation/H+ Antiporters.

The processes of plant nutrition, stress tolerance, plant growth, and development are strongly dependent on transport of mineral nutrients across cellular membranes. Plant membrane transporters are key components of these processes. Among various membrane transport proteins, the monovalent cation proton antiporter (CPA) superfamily mediates a broad range of physiological and developmental processes such as ion and pH homeostasis, development of reproductive organs, chloroplast operation, and plant adaptation to drought and salt stresses. CPA family includes plasma membrane-bound Na+/H+ exchanger (NhaP) and intracellular Na+/H+ exchanger NHE (NHX), K+ efflux antiporter (KEA), and cation/H+ exchanger (CHX) family proteins. In this review, we have completed the phylogenetic inventory of CPA transporters and undertaken a comprehensive evolutionary analysis of their development. Compared with previous studies, we have significantly extended the range of plant species, including green and red algae and Acrogymnospermae into phylogenetic analysis. Our data suggest that the multiplication and complexation of CPA isoforms during evolution is related to land colonisation by higher plants and associated with an increase of different tissue types and development of reproductive organs. The new data extended the number of clades for all groups of CPAs, including those for NhaP/SOS, NHE/NHX, KEA, and CHX. We also critically evaluate the latest findings on the biological role, physiological functions and regulation of CPA transporters in relation to their structure and phylogenetic position. In addition, the role of CPA members in plant tolerance to various abiotic stresses is summarized, and the future priority directions for CPA studies in plants are discussed.

Biostimulant Application with a Tropical Plant Extract Enhances Corchorus olitorius Adaptation to Sub-Optimal Nutrient Regimens by Improving Physiological Parameters

The emerging role of plant biostimulants in enhancing nutrient efficiency is important for maintaining soil fertility under sub-optimal nutrient regimens. We aimed to elucidate the morpho-physiological and biochemical effects as well as mineral composition changes of greenhouse jute (Corchorus olitorius L.) treated with a commercial vegetal-derived biostimulant from a tropical plant extract (PE; Auxym®, Italpollina, Rivoli Veronese, Italy). Plants were sprayed in weekly intervals with a solution containing 2 mL·L−1 PE. Jute plants were supplied with three nutrient solution concentrations: full-, half-, and quarter-strength. Decreasing macronutrient concentrations in the nutrient solution (NS), especially at quarter-strength, triggered a decrease in several morphological (plant height, leaf number, and dry biomass) and physiological (net CO2 assimilation rate (ACO2) and SPAD (Soil Plant Analysis Development) index) parameters. PE application triggered specific ameliorative effects in terms of fresh yield at both half- and quarter-strength nutrient solution (15.5% and 29.5%, respectively). This was associated with an enhancement in ACO2, SPAD index, and especially the nutritional status (high nitrate, K, and Mg contents, and low Na content). The foliar application of PE, strongly increased chlorophyll b content, enhancing jute plant adaptation to fluctuating light and therefore the efficiency of photosynthesis, positively affecting starch, soluble proteins, and total amino acids content but only when jute plants were irrigated with full-strength NS, compared to the respective control treatment. At lower nutrient strength, PE reprogrammed the nitrogen distribution, allowing its remobilization from glutamate, which was quantitatively the major amino acid under lower nutrient strength, but not from chlorophylls, thus maintaining efficient photosynthesis. We confirmed that PE Auxym® acts in a balanced manner on the main metabolic pathways of the plant, regulating the uptake and transport of mineral nutrients and protein synthesis, increasing the accumulation of essential amino acids under full nutritive solutions, and re-distributing nitrogen from amino acids to allow leaf growth and expansion even under sub-optimal nutrient conditions. Overall, the use of natural plant biostimulants may be a potential solution in low-input conditions, where environmental constraints and restricted use of fertilizers may affect potential crop productivity.

Strategies for optimization of mineral nutrient transport in plants: multilevel regulation of nutrient-dependent dynamics of root architecture and transporter activity.

How do sessile plants cope with irregularities in soil nutrient availability? The uptake of essential minerals from the soil influences plant growth and development. However, most environments do not provide sufficient nutrients; rather nutrient distribution in the soil can be uneven and change temporally according to environmental factors. To maintain mineral nutrient homeostasis in their tissues, plants have evolved sophisticated systems for coping with spatial and temporal variability in soil nutrient concentrations. Among these are mechanisms for modulating root system architecture in response to nutrient availability. This review discusses recent advances in knowledge of the two important strategies for optimizing nutrient uptake and translocation in plants: root architecture modification and transporter expression control in response to nutrient availability. Recent studies have determined (i) nutrient-specific root patterns; (ii) their physiological consequences; and (iii) the molecular mechanisms underlying these modulation systems that operate to facilitate efficient nutrient acquisition. Another mechanism employed by plants in nutrient-heterogeneous soils involves modification of nutrient transport activities in a nutrient concentration-dependent manner. In recent years, considerable progress has been made in characterizing the diverse functions of transporters for specific nutrients; it is now clear that the expression and activities of nutrient transporters are finely regulated in multiple steps at both the transcriptional and post-transcriptional levels for adaptation to a wide range of nutrient conditions.

Altered physiology, cell structure, and gene expression of Theobroma cacao seedlings subjected to Cu toxicity

Seedlings of Theobroma cacao CCN 51 genotype were grown under greenhouse conditions and exposed to increasing concentrations of Cu (0.005, 1, 2, 4, 8, 16, and 32mg Cu L(-1)) in nutrient solution. When doses were equal or higher than 8mg Cu L(-1), after 24h of treatment application, leaf gas exchange was highly affected and changes in chloroplasts thylakoids of leaf mesophyll cells and plasmolysis of cells from the root cortical region were observed. In addition, cell membranes of roots and leaves were damaged. In leaves, 96h after treatments started, increases in the percentage of electrolyte leakage through membranes were observed with increases of Cu in the nutrient solution. Moreover, there was an increase in the concentration of thiobarbituric acid-reactive substances in roots due to lipid peroxidation of membranes. Chemical analysis showed that increases in Cu concentrations in vegetative organs of T. cacao increased with the increase of the metal in the nutrient solution, but there was a greater accumulation of Cu in roots than in shoots. The excess of Cu interfered in the levels of Mn, Zn, Fe, Mg, K, and Ca in different organs of T. cacao. Analysis of gene expression via RTq-PCR showed increased levels of MT2b, SODCyt, and PER-1 expression in roots and of MT2b, PSBA, PSBO, SODCyt, and SODChI in leaves. Hence, it was concluded that Cu in nutrient solution at doses equal or above 8mgL(-1) significantly affected leaf gas exchange, cell ultrastructure, and transport of mineral nutrients in seedlings of this T. cacao genotype.

Sebacinales Everywhere: Previously Overlooked Ubiquitous Fungal Endophytes

Inconspicuous basidiomycetes from the order Sebacinales are known to be involved in a puzzling variety of mutualistic plant-fungal symbioses (mycorrhizae), which presumably involve transport of mineral nutrients. Recently a few members of this fungal order not fitting this definition and commonly referred to as ‘endophytes’ have raised considerable interest by their ability to enhance plant growth and to increase resistance of their host plants against abiotic stress factors and fungal pathogens. Using DNA-based detection and electron microscopy, we show that Sebacinales are not only extremely versatile in their mycorrhizal associations, but are also almost universally present as symptomless endophytes. They occurred in field specimens of bryophytes, pteridophytes and all families of herbaceous angiosperms we investigated, including liverworts, wheat, maize, and the non-mycorrhizal model plant Arabidopsis thaliana. They were present in all habitats we studied on four continents. We even detected these fungi in herbarium specimens originating from pioneering field trips to North Africa in the 1830s/40s. No geographical or host patterns were detected. Our data suggest that the multitude of mycorrhizal interactions in Sebacinales may have arisen from an ancestral endophytic habit by specialization. Considering their proven beneficial influence on plant growth and their ubiquity, endophytic Sebacinales may be a previously unrecognized universal hidden force in plant ecosystems.

Root Development and Nutrient Uptake

Root system formation proceeds in close coordination with shoot growth. Accordingly, root growth and its functions are regulated tightly by the shoot through materials cycling between roots and shoots. A plant root system consists of different kinds of roots that differ in morphology and functions. The spatial configuration and distribution of these roots determine root system architecture in the soil, which in turn primarily regulates the acquisition of soil resources like nutrients and water. Morphological and physiological properties of each root and the concomitant tissues further affect nutrient uptake and transport, while the root traits that are related to such acquisition also depend on the kinds of nutrients and their mobility in the soil. In addition, mechanisms involved in the uptake and transport of mineral nutrients recently have been elucidated at the molecular level. A number of genes for acquisition and transport of various mineral nutrients have been identified in model plant systems such as Arabidopsis thaliana, and rice, and in other plant species. An integration of studies on nutrient behavior in soils and the morphological and physiological functions of root systems will further elucidate the mechanism of plant nutrient uptake and transport by roots, and offer a real possibility of genetically improving crop productivity in problem soils. Referee: Dr. Bobbie McMichael, Plant Physiologist, USDA-ARS, Plant Stress and Germplasm Development Unit, 3810 4th St., Lubbock, Texas 79415

Morphology of flux-grown vanadate garnets

The morphologies of vanadate garnets (NaCa 2M 2V 3O 12, M=Ni, Mg or Co) were studied by growing well-formed crystals from sodium vanadate flux. The first rank F-faces were determined by growing crystals at low supersaturation levels and were found to be the {1 1 0} face at lower temperature and the {2 1 1} face at higher temperature. This change was ascribed to a change in the ratio of the bond lengths at the octahedral site to that of the dodecahedral site with increasing temperature. When crystals grew larger in the lower temperature region, predominantly {2 1 1} faces appeared in addition to {1 1 0} faces, whereas in the higher temperature region, {1 1 0} faces were predominant over {2 1 1} faces. The reason for these phenomena was ascribed to the surface kinetics caused by an increase in the rate of mineral nutrient transport to the surface of the crystal with increasing crystal size.

Interaction of copper (Cu) on the dynamic behavior of mineral nutrients in soil-plant system

A pot culture experiment was carried out to assess the influence of soil added copper (Cu) on the availability and transport of mineral nutrients (MNs) such as Na, K, Ca, Mg, P and N. The results showed that the influence of Cu in the rhizosphere environment on the dynamic behavior of mineral nutrients is concentration dependent. Increasing levels of Cu in the soil increases the availability of Na, K, Mg and P. whereas the availability of Ca was affected. As far as the mobility of MNs is concerned, Cu in soil increases the soil to leaf mobility of Ca and N, whereas it affected the mobility of Na, K and Mg. The influence of Cu on the mobility of P from the soil to leaf shown to be neutral.

Mineral nutrient transport by sunflower seedlings grown under saline conditions (NaCl)

Sunflower seeds (Helianthus annuus L., cv. Dwarf) were grown with distilled water only or increasingly saline solutions (NaCl) to determine the influence of salinity on seedling growth and on the distribution of mineral nutrients obtained exclusively from cotyledons. Seedling growth was decreased by moderate (50mM) and high (100mM) concentrations of NaCl in the growth solution. Salinity generally decreased mineral transport (especially Fe, Mn, Mg, and Ca) from seed to seedling, except for K. Transport of Fe, Mg, and Ca to the aerial part was also markedly reduced.

Cadmium effects on influx and transport of mineral nutrients in plant species

Abstract Solution culture experiments were conducted under controlled environmental conditions to determine the effects of cadmium(II) [Cd(II)] activity (0, 8, 14, 28, 42, and 54 μM) on influx (IN) into roots and transport (TR) from roots to shoots of zinc (Zn), copper (Cu), iron (Fe), manganese (Mn), calcium (Ca), magnesium (Mg), phosphorus (P), and sulfur (S) in ryegrass (Lolium perenne L.), maize (Zea mays L.), white clover (Trifolium repens L.), and cabbage (Brassica oleracea var. capitata L.). Shoot and root dry matter (DM) decreased with increased external Cd, and plant species differed extensively. Ryegrass and cabbage were relatively tolerant to Cd toxicity compared to white clover and maize. Influx and TR of Cu, Zn, Fe, Mn, Ca, and Mg were lower with increasing external Cd compared to controls, and species also differed. Influx and TR of P were enhanced in each species with up to 14 μM Cd, decreased in white clover and cabbage at higher Cd levels, while in maize and ryegrass continued to increase as Cd increased. Influx and TR of S were high in white clover at 8 μM Cd and decreased as Cd increased. Influx of S was high in ryegrass, but TR of S remained relatively constant as Cd increased. Influx and TR of S did not significantly change in maize, but decreased in cabbage as Cd increased. With Cd up to 14 μM, decreases in both IN and TR of Zn, Fe, Mn, Ca, and Mg were greater in white clover than in cabbage. Sensitivity of the dicotyledonous plant species to Cd toxicity might have been associated with Cd effects on IN and TR of Fe, Mn, Ca, and Mg. However, differences in plant sensitivities to Cd toxicity between ryegrass and maize were not reflected in Cd effects on IN and TR of mineral nutrients.

Plant tolerance to nickel toxicity: II nickel effects on influx and transport of mineral nutrients in four plant species

Abstract Nickel (Ni) is an essential micronutrient for higher plants but is toxic to plants at excess levels. Plant species differ extensively for mineral uptake and accumulation, and these differences often help explain plant tolerances to mineral toxicities/deficiencies. Solution culture experiments were conducted under controlled conditions to determine the effects of Ni on influx into roots (IN) and transport from roots to shoots (TR) of zinc (Zn), iron (Fe), copper (Cu), manganese (Mn), calcium (Ca), magnesium (Mg), phosphorus (P), and sulfur (S) in white clover (Trifolium repens L.), cabbage (ßrassica oleracea van capitata L.), ryegrass (Lolium perenne L.), and maize (Zea mays L.). Nickel decreased both IN and TR of Zn, Cu, Ca, and Mg, but only TR of Fe and Mn in white clover. Both IN and TR of Cu, Fe, Mn, Mg, and S were markedly decreased by Ni >30 μM in cabbage, whereas IN and TR of P increased with Ni treatment. For ryegrass, TR of Cu, Fe, Mn, Ca, and Mg was decreased, but IN of these elements except Mg was not affected by Ni. The IN and TR of P and S were increased in ryegrass with increasing external Ni levels. Nickel inhibited IN of Cu, Ca, and Mg, and TR of Zn, Cu, Fe, Mn, Ca, and Mg in maize. Plant species differed in response to Ni relative to IN and TR of mineral nutrients. Plant tolerance to Ni toxicity was associated with the influence of Ni on IN and TR of Cu, Fe, and Mn in white clover and cabbage but not in maize and ryegrass.

An Introduction to Crop Physiology

Prefaces Acknowledgements 1. Prolegomena 2. The environment 3. The supply and use of water 4. The absorption and transport of mineral nutrients 5. Photosynthesis and respiration 6, Germination and seeding emergence 7. vegetative growth 8. Flowering and fruit growth 9. Some aspects of overall growth and its modification 10. The prediction of responses Glossary Appendices Index.

Metabolism of Glucose and Acetate in Chlorella Cell in Relation to the Active Transport of Mineral Nutrients

Metabolism of Glucose and Acetate in Chlorella Cell in Relation to the Active Transport of Mineral Nutrients