Ion Uptake In Plants Research Articles

Study on the mechanism of salt relief and growth promotion of Enterobacter cloacae on cotton

AimsIn-depth studies on plant ion uptake and plant growth-promoting rhizobacteria (PGPR) at the molecular level will help to further reveal the effects of PGPR on plants and their interaction mechanisms under salt stress.MethodsCotton was inoculated with a PGPR-Enterobacter cloacae Rs-35, and the ion uptake capacity, membrane transporter protein activity, and expression of key genes were determined under salt stress. Changes in the endogenous hormone content of cotton were also determined. Further, the genome-wide metabolic pathway annotation of E. cloacae Rs-35 and its differential enrichment pathway analysis of multi-omics under salinity environments were performed.ResultsIn a pot experiment of saline-alkali soil, E. cloacae Rs-35-treated cotton significantly increased its uptake of K+ and Ca2+ and decreased uptake of Na+, elevated the activity of the H+-ATPase, and increased the sensitivity of the Na+/H+ reverse transporter protein on the vesicle membrane. Meanwhile, inoculation with E. cloacae Rs-35 could promote cotton to maintain the indole-3-acetic acid (IAA) content under salt stress. Genome-wide annotation showed that E. cloacae Rs-35 was respectively annotated to 31, 38, and 130 related genes in osmotic stress, phytohormone and organic acid metabolism, and ion uptake metabolic pathway. Multi-omics differences analysis showed that E. cloacae Rs-35 were enriched to tryptophan metabolism, multiple amino acid biosynthesis, carbon and glucose synthesis, and oxidative phosphorylation metabolic pathways at the transcriptome, proteome, and metabolome.ConclusionE. cloacae Rs-35 can promote cotton balance cell ion concentration, stabilize intracellular IAA changes, stimulate induction of systemic tolerance, and promote the growth of cotton plants under salt stress.

Effect of zinc imbalance and salicylic acid co-supply on Arabidopsis response to fungal pathogens with different lifestyles.

In higher plants, Zn nutritional imbalance can affect growth, physiology and response to stress, with effect variable depending on host–pathogen interaction. Mechanisms through which Zn operates are not yet well known. The hormone salicylic acid (SA) can affect plant ion uptake, transport and defence responses. Thus, in this study the impact of Zn imbalance and SA co‐supply on severity of infection with the necrotrophic fungal pathogen B. cinerea or the biotroph G. cichoracearum was assessed in A. thaliana Col‐0.Spectrophotometric assays for pigments and malondialdehyde (MDA) content as a marker of lipid peroxidation, plant defensin 1.2 gene expression by semi‐quantitative PCR, callose visualization by fluorescence microscopy and diseases evaluation by macro‐ and microscopic observations were carried out.Zinc plant concentration varied with the supplied dose. In comparison with the control, Zn‐deficit or Zn‐excess led to reduced chlorophyll content and PDF 1.2 transcripts induction. In Zn‐deficient plants, where MDA increased, also the susceptibility to B. cinerea increased, whereas MDA decreased in G. cichoracearum. Zinc excess increased susceptibility to both pathogens. Co‐administration of SA positively affected MDA level, callose deposition, PDF 1.2 transcripts and plant response to the two pathogens.The increased susceptibility to B. cinerea in both Zn‐deficient and Zn‐excess plants could be related to lack of induction of PDF 1.2 transcripts; oxidative stress could explain higher susceptibility to the necrotroph and lower susceptibility to the biotroph in Zn‐deficient plants. This research shows that an appropriate evaluation of Zn supply according to the prevalent stress factor is desirable for plants.

Foliar fertigation of ascorbic acid and zinc improves growth, antioxidant enzyme activity and harvest index in barley (Hordeum vulgare L.) grown under salt stress

Crop productivity is limited by several environmental constraints. Among these, salt stress plays a key role in limiting the growth and yield production of economically important agricultural crops. However, the exogenous fertigation of vitamins and minerals could serve as a “shot-gun” approach for offsetting the deleterious effects of salts present in the rhizosphere. Therefore, an experiment was conducted to quantify the efficacy of foliar fertigation of ascorbic acid (vitamin-C) and zinc (Zn) on the physio-biochemical attributes of barley (Hordeum vulgare L. Genotype B-14011) grown in a saline environment. The salt stress resulted in a reduced biological yield associated with a decrease in chlorophyll pigment, while a significant enhancement in Na+ and Zn2+ was observed under salinity stress. Similarly, the contents of total soluble proteins, total free amino acids, lipid peroxidation, and H2O2 and the activities of antioxidative enzymes (SOD, POD, CAT, APX and proline) were significantly enhanced under salinity stress. Moreover, salinity negatively affected the yield attributes and ion uptake of plants. However, foliar fertigation with AsA +0.03% Zn enhanced vegetative growth, photosynthetic pigments, synchronized ion uptake, the synthesis of enzymatic and non-enzymatic antioxidants, and the harvest index. It is inferred from this study that among all treatments, the effect of foliar fertigation with the AsA+0.03% Zn combination not only improved the salt stress tolerance but also improved the yield attributes, which will aid in the improvement in barley seed yield and is a step to solve the problem of malnutrition through biofortification of vitamin-C and zinc.

Arabidopsis CNGC Family Members Contribute to Heavy Metal Ion Uptake in Plants.

Heavy metal ions, including toxic concentrations of essential ions, negatively affect diverse metabolic and cellular processes. Heavy metal ions are known to enter cells in a non-selective manner; however, few studies have examined the regulation of heavy metal ion transport. Plant cyclic nucleotide-gated channels (CNGCs), a type of Ca2+-permeable-channel, have been suggested to be involved in the uptake of both essential and toxic cations. To determine the candidates responsible for heavy metal ion transport, a series of Arabidopsis CNGC mutants were examined for their response to Pb2+ and Cd2+ ions. The primary focus was on root growth and the analysis of the concentration of heavy metals in plants. Results, based on the analysis of primary root length, indicated that AtCNGC1, AtCNGC10, AtCNGC13 and AtCNGC19 play roles in Pb2+ toxicity, while AtCNGC11, AtCNGC13, AtCNGC16 and AtCNGC20 function in Cd2+ toxicity in Arabidopsis. Ion content analysis verified that the mutations of AtCNGC1 and AtCNGC13 resulted in reduced Pb2+ accumulation, while the mutations of AtCNGC11, AtCNGC15 and AtCNGC19 resulted in less Pb2+ and Cd2+ accumulation in plants. These findings provide functional evidence which support the roles of these AtCNGCs in the uptake and transport of Pb2+ or Cd2+ ion in plants.

Aerated Irrigation and Pruning Residue Biochar on N2O Emission, Yield and Ion Uptake of Komatsuna

After irrigation in intensive vegetable cultivation, the soil is filled with water leading to reduced oxygen content of the soil air which will affect vegetable growth and soil N2O emission. In this study, the effect of aerated irrigation and residue biochar on soil N2O emission, yield, and ion uptake of komatsuna grown in Andosol was explored. The experiment included four treatments; control (tap water irrigation), aerated water irrigation, pruning residue biochar with tap water irrigation, and a combination of aerated irrigation and biochar. The results showed that aerated irrigation had no effect on plant growth, but it also increased N2O emission by 12.3% for several days after planting. Plant ion uptake was not affected by aerated irrigation. Biochar amendment increased shoot dry weight and significantly reduced soil N2O emission by 27.9% compared with the control. Plant uptake of N and K also increased with biochar. This study showed that pruning residue biochar has the potential to mitigate N2O emission while increasing vegetable growth and plant nutrient uptake. However, the study soil, Andosol, already has high soil porosity with low bulk density. Thus, further injection of air through irrigation showed no effect on plant growth but increased N2O emission, hence soil aeration was not a limiting factor in Andosol.

Reduction of geomagnetic field (GMF) to near null magnetic field (NNMF) affects Arabidopsis thaliana root mineral nutrition

The Earth magnetic field (or geomagnetic field, GMF) is a natural component of our planet and variations of the GMF are perceived by plants with a still uncharacterized magnetoreceptor. The purpose of this work was to assess the effect of near null magnetic field (NNMF, ∼40 nT) on Arabidopsis thaliana Col0 root ion modulation. A time-course (from 10 min to 96 h) exposure of Arabidopsis to NNMF was compared to GMF and the content of some cations (NH4+, K+, Ca2+ and Mg2+) and anions (Cl−, SO4=, NO3− and PO4=) was evaluated by capillary electrophoresis. The expression of several cation and anion channel- and transporter-related genes was assessed by gene microarray. A few minutes after exposure to NNMF, Arabidopsis roots responded with a significant change in the content and gene expression of all nutrient ions under study, indicating the presence of a plant magnetoreceptor that responds immediately to MF variations by modulating channels, transporters and genes involved in mineral nutrition. The response of Arabidopsis to reduced MF was a general reduction of plant ion uptake and transport. Our data suggest the importance to understand the nature and function of the plant magnetoreceptor for future space programs involving plant growth in environments with a reduced MF.

Multiphasic Profiles: Discontinuous Transitions in Conductance-Voltage Data for Ion Channels

Multiphasic profiles, a series of straight lines separated by discontinuous transitions, were first found (Nissen, Annu. Rev. Plant Physiol. 1974) for the concentration-dependence, plotted in linear transformations of the Michaelis-Menten equation, for ion uptake in plants. Reanalyses of recently published data show that conductance-voltage data for ion channels are also well represented as multiphasic. In contrast, the Boltzmann function and other functions giving curvilinear profiles must often be rejected for statistical reasons (very low probabilities by the Runs test that the uneven distribution of points around the profiles is due to chance). Plots of deviates show that the fits to multiphasic profiles are usually better than the fits to curvilinear profiles, i.e. that the data are more precise than apparent from the published plots. As shown by simulation, the better fits to multiphasic profiles are not due to errors (noise) in the data. Adjacent lines are often parallel. The transitions are then necessarily in the form of noncontiguities (jumps). Non-parallel lines are also frequently separated by jumps. Most often, replicate determinations give different multiphasic patterns (number of phases, voltages at which the transitions occur). The use of the averages will then give a meaningless pattern.Whenever the data are sufficiently detailed and precise, multiphasic profiles are also found for a variety of other processes and systems, biological as well as nonbiological: 1) pH profiles, including profiles for non-enzymatic model systems. 2) Binding as determined by fluorescence anisotropy titration or isothermal titration calorimetry (ITC). 3) Folding and unfolding of proteins.Implications for the opening and closing of single biological channels will be discussed.

Effects of Renewal Pattern of Recycled Nutrient Solution on the Ion Balance in Nutrient Solutions and Root Media and the Growth and Ion Uptake of Paprika (Capsicum annuum L.) in Closed Soilless Cultures

Ion imbalance in recycled nutrient solutions is caused by selective ion uptake of plants, which occurs at different rates in different growth stages. The objectives of this study were to investigate the ion balances in both recycled nutrient solutions and rockwool media using different renewal patterns for the nutrient solutions, and to analyze the subsequent effects on uptake of water and nutrients. Over 12 weeks of paprika cultivation, two different renewal patterns (week units) of 6-4-2 and 8-2-2 weeks were compared with a constant renewal pattern of 4-4-4 weeks (control). The nutrient solution in the reservoir tank was constantly maintained at EC <TEX>$2.5dS{\cdot}m^{-1}$</TEX> and pH 5.5-6.5. The changes in the ion balance with the 4-4-4 week pattern were smaller than those with the other treatments. In the early growth stage, however, the ion balances similarly changed among all treatments. Greater changes were subsequently observed for the 6-4-2 week pattern. Although fruit yield and shoot fresh weight of paprika were the lowest with 6-4-2 renewal pattern, no significant differences were observed. Our results indicate that renewal intervals can be extended in consideration of growth stage for more efficient and practical operations in closed soilless cultures.

Isolation and characterization of 24-Epibrassinolide from Brassica juncea L. and its effects on growth, Ni ion uptake, antioxidant defense of Brassica plants and in vitro cytotoxicity

Brassinosteroids (BRs) are a group of steroidal plant hormones which are essential for growth and development of plants. These hormones affect plant growth and development through a spectrum of physiological responses. Recent reports showed their stress-protective, antiviral, antitumor and antigenotoxic potential. In the present study, an attempt was made to isolate 24-Epibrassinolide from 30-days-old Brassica juncea L. plants which was characterized by ESI–MS analysis. The ESI–MS analysis of isolated Brassinolide was compared with the standard 24-Epibrassinolide, which confirmed its MS/MS fragmentation pattern. Various concentrations of the isolated brassinosteroid were given as pre-sowing treatment to the seeds of B. juncea for 8 h. The pre-treated seeds were then raised in experimental pots containing different concentrations of nickel ion. After 30 days, plants were harvested and analyzed for growth parameters, ion uptake and antioxidant defense system. It was observed that pre-treatment of isolated 24-Epibrassinolide lowered the Ni ion uptake in plants and improved growth. The amelioration of Ni toxicity was also observed by the activities of antioxidant enzymes. The in vitro cytotoxicity of natural 24-Epibrassinolide against different cancer cell lines was checked by employing sulphorhodamine bioassay and it revealed significant inhibition in the lung cancer cell line.

Alleviation by calcium of cadmium-induced root growth inhibition in Arabidopsis seedlings

Cadmium (Cd) is a highly toxic element for living organisms. Its toxicity and the thereof by calcium (Ca) in 2-week-old Arabidopsis seedlings were studied. The seedlings were treated with Cd at concentrations of 50–500 µM for 24 h. Retardation of root growth was evident through increased cell death at the root elongation zone. Supplementing with 30 mM Ca restored root elongation in the presence of up to 200 µM Cd, resulting in up to a 1/3 decrease in Cd content in the seedlings compared to Arabidopsis treated with Cd alone. Ca was able to alleviate Cd toxicity, presumably through competition for metal ion influx. These results provide us with information regarding plant ion uptake systems and metal ion toxicities.

Copper Activity in Soil Solution: II. Relation to Copper Accumulation in Young Snapbeans

AbstractSoil solution Cu2+ activity measured in soil saturation extracts was compared with Cu accumulation in young snapbeans (Phaseolus vulgaris L.). Copper was supplied through sewage sludge mixtures of varied Cu concentrations and through Cu‐salt additions to the soil. Treatments were a factorial combination of four levels of Cu additions and four levels of total sludge additions. Soil and sludge pH values were limited to pH 5.0 to 5.5. Plant yield differences were minor. Data are reported showing the relationships of root, shoot, and total plant Cu contents with Cu2+ activity, with DTPA‐extractable Cu, with soluble Cu, and with sludge Cu concentration. The Cu source (sludge vs. salt) produced distinctly different curves in most every case. Sludge treatments demonstrated nonlinear relationships of Cu activity vs. Cu accumulation; these were fit with exponential functions. Higher shoot Cu concentrations occurred with the Cu salt treatments. Higher root Cu levels occurred at lower Cu2+ activity values with sludge as the Cu source. This probably reflects the superior ability of the sludge to replenish or maintain the Cu supply in soil solution. Total soluble Cu was not related to plant Cu. The proportion of Cu in the sludge was closely linked with shoot Cu (r2 = 0.94); root Cu levels also reflected the proportion of Cu in the sludge, but higher sludge rates resulted in increased root Cu. Increased labile, soluble, Cu‐organic complexes with increased sludge rates would explain both the observed differences between salt and sludge treatments and the positive correlation of root Cu and sludge rate. Physiological control of Cu translocation within the plant is implicit in this reasoning. Continual monitoring of soil solution ion activity or a buffering index is needed to improve predictions of plant ion uptake.

Peptide Alcohols as Promoters of Nitrate and Ammonium Ion Uptake in Plants

Several aryl-carbamoyl dipeptide alcohols increased the uptake of nitrate and ammonium ions into corn root segments by up to 50% and 90%, respectively. The most effective one was N-carbobenzoxy-l-prolyl-l-valinol. Foliar application of this compound to underfertilized corn plants caused an increase in the rate of plant growth in the greenhouse and provided modest (6-10%) corn yield increases in field tests in Delaware.

Autoradiography of 35SO 4 in plant tissue

An improved technique for the study of ion uptake in plants has been evolved by combining a controlled temperature freezing-sectioning method for plant tissues with an autoradiographic method for studying water-soluble compounds. Preliminary results with 35SO 4 have demonstrated the presence of a higher concentration of ions in the stele than the cortex on feeding for 14 hr.