Roots Of Barley Seedlings Research Articles

Effects of Exogenous Linoleic Acid on Barley (Hordeum vulgare L.) Seedlings Under Salinity

Salt stress adversely affects plants and causes different levels of morphological, physiological, biochemical, and molecular changes at different growth stages. Polyunsaturated fatty acids (PUFAs), such as linoleic acid, are main components of membrane lipids and determine the fluidity and stability of the cell membrane. In addition, PUFAs have a crucial role in maintaining the structure and function of the cell membrane which is damaged by salinity. There may be a relationship between level of PUFAs in membrane lipids and salinity tolerance. The present study was carried out to examine the effects of exogenous application of 0.5 mM linoleic acid (LA) on barley seedlings (Hordeum vulgare L. cv. Martı) grown in hydroponic conditions under 160 mM NaCl. The treatment with LA ameliorated the stress generated by NaCl by increasing osmolyte level and decreasing ion leakage percentage and H2O2 content within hours. Besides, LA significantly enhanced expression of salt-responsive transcription factor HvDRF2 and ROS scavenger gene HvMT2 as 105- and 40-fold, respectively, in the leaves of barley seedlings under salinity conditions. While LA slightly increased the gene expression of ascorbate peroxidase (HvAPX), glutathione S-transferase (HvGST6) and copper zinc superoxide dismutase (HvCu/ZnSOD) in the roots of barley seedlings, the expression of these genes was not changed in the leaves under salinity compared to salt-stressed samples. This study provides novel insights for effects of LA on improvement of salinity tolerance in barley.

Anaerobiosis modulation of two phytoglobins in barley (Hordeum vulgare L.), and their regulation by gibberellin and abscisic acid in aleurone cells

The transcript levels of the phytoglobin (Pgb) genes Pgb1 and Pgb3, and the protein content of Pgb1 were responsive to anaerobiosis in several tissues of barley (Hordeum vulgare L.). Oxygen deficiency induced the level of both Pgb transcripts and protein in aleurone layers and coleoptiles, as well as up-regulated both Pgb1 and Pgb3 in leaves, apexes and more strongly in roots of barley seedlings. In O2-depleted aleurone cells the induction of the Pgb transcript-protein pair was reversed by re-supplying O2. Based on this observation, it is suggested that Pgb1 and Pgb3 are inducible in all tissues. In aleurone cells, gibberellic acid (GA) induced Pgb1 and Pgb3 together with α-amylase, whereas abscisic acid (ABA) eliminated the GA stimulating effects on both α-amylase and Pgb1 and Pgb3 expression. While GA had no effects on alcohol dehydrogenase (Adh1, Adh2 and Adh3) transcripts, ABA induced all three Adh genes. It is concluded that Pgb and α-amylase in seeds are regulated reciprocally with the ethanolic fermentation pathway, and that Pgb induction is mediated by GA. Nitric oxide turnover and scavenging mediated by Pgb represents an important alternative to fermentation under anoxia.

Hordatines and Associated Precursors Dominate Metabolite Profiles of Barley (Hordeum vulgare L.) Seedlings: A Metabolomics Study of Five Cultivars

In the process of enhancing crop potential, metabolomics offers a unique opportunity to biochemically describe plant metabolism and to elucidate metabolite profiles that govern specific phenotypic characteristics. In this study we report an untargeted metabolomic profiling of shoots and roots of barley seedlings performed to reveal the chemical makeup therein at an early growth stage. The study was conducted on five cultivars of barley: ‘Overture’, ‘Cristalia’, ‘Deveron’, ‘LE7′ and ‘Genie’. Seedlings were grown for 16 days post germination under identical controlled conditions, and methanolic extracts were analysed on an ultra-high performance liquid chromatography coupled to high-resolution mass spectrometry (UHPLC–HRMS) system. In addition, an unsupervised pattern identification technique, principal component analysis (PCA), was performed to process the generated multidimensional data. Following annotation of specific metabolites, several classes were revealed, among which phenolic acids represented the largest group in extracts from both shoot and root tissues. Interestingly, hordatines, barley-specific metabolites, were not found in the root tissue. In addition, metabolomic profiling revealed metabolites potentially associated with the plants’ natural protection system against potential pathogens. The study sheds light on the chemical composition of barley at a young developmental stage and the information gathered could be useful in plant research and biomarker-based breeding programs.

Рентгеновская компьютерная томография структуры корней и динамика почвенной биоты на ранних стадиях роста ячменя (Hordeum vulgare L.)

The architecture of the seed bed, a certain alternation of compacted and loose sections of the arable horizon, largely determines the development of the root system of plants. The morphology and growth of the root system of the germinating seed in the created seed bed is also determined by the composition of the surrounding soil biota. Dynamic studies of the development of the root system and composition of the surrounding soil biota is an essential methodological and practical problem in soil cultivation, agrophysics, and soil biology. This task is especially important in the first few days when the root system is laid and the plant rhizosphere is formed. Modern tomography makes it possible to carry out such studies that do not violate the soil-root biological system, in particular, in model mesoscale experimental physical models. The aim of this research was to use x-ray computed tomography to study the structure of the roots of barley seedlings in the early stages of development, while simultaneously studying changes in the number and dominant groups of microorganisms in the basal biota. Barley seeds (variety Mikhailovsky) in a model physical experiment with a twolayer soil bed density (soil density range from 0.7 to 1.2 g / cm3) Albic Glossic Retisols (Lomic, Cutanic), WRB, 2014 were laid for germination at the layer boundary in a special cylindrical box with a volume of about 3 cm3 at optimal humidity. The position of the seed in the soil of the seedbed model is shown in the tomographic image (See Fig. 1). During the period from planting to 7 days, the dynamics of the root system was studied using a Bruker X-ray microtomography “SkyScan 1172G” (Bruker, Belgium) while studying the composition of soil biota, which was reconstructed by microbial markers (fatty acids and their derivatives). Markers were determined by molecular gas chromatography - mass spectrometry. Computer tomography allowed to record the volume distribution of roots at different periods of germination in the aggregated and compacted layers of agro-sod-podzolic soil. In this case, the roots successfully mastered the entire soil space, regardless of the plowing architecture of soil density created at the initial stage of germination. The total number of bacteria also increased by the 5th day with the constant dominance of 3 phyla: Actinobacteria, Proteobacteria and Firmicutes in the biota; the other two, Bacteroidetes and Cyanobacteria, were represented in relatively small numbers. In the phylum Actinobacteria, aerobic hydrolytics of complex carbohydrates Rhodococcus equi were presented in the largest amount on the 5th day, in the Firmicutes phylum it is anaerobic hydrolytic Ruminococcus sp. and the anaerobic nitrogen fixator Clostridium pasteurianum, in the phylum Proteobacteria-the aerobic nitrifier Nitrobacter sp. with a subsequent decrease in the number on the 7th day. The increase in these species indicates the initial destruction of the cellulose shell of the grain and the processes of fixation and conversion of nitrogen in the microbiota of the germinating seed, necessary for the formation of the C/N ratio. During the germination of the seed, pores are formed that are filled with water, gas, or organic matter. The structure of the microbial community changes in response to the ongoing processes, while the accumulation of metabolic products of aerobic and anaerobic species of microorganisms occurs. The quantitative study of the complex of microorganisms by the molecular method allows us to display the reaction of the microbiome to structural changes in the soil, since certain conditions stimulate an increase in the share of species with appropriate ecological functions in the community. The combination with the computer visualization obtained as a result of the application of the X-ray tomography method makes it possible to more clearly characterize the processes occurring in the rhizosphere.

Barley Root Proteome and Metabolome in Response to Cytokinin and Abiotic Stimuli.

Cytokinin is a phytohormone involved in the regulation of diverse developmental and physiological processes in plants. Its potential in biotechnology and for development of higher-yield and more resilient plants has been recognized, yet the molecular mechanisms behind its action are far from understood. In this report, the roots of barley seedlings were explored as a new source to reveal as yet unknown cytokinin-responsive proteins for crop improvement. Here we found significant differences reproducibly observed for 178 proteins, for which some of the revealed cytokinin-responsive pathways were confirmed in metabolome analysis, including alterations phenylpropanoid pathway, amino acid biosynthesis and ROS metabolism. Bioinformatics analysis indicated a significant overlap between cytokinin response and response to abiotic stress. This was confirmed by comparing proteome and metabolome profiles in response to drought, salinity or a period of temperature stress. The results illustrate complex abiotic stress response in the early development of model crop plant and confirm an extensive crosstalk between plant hormone cytokinin and response to temperature stimuli, water availability or salinity stress.

Pilot study on the uptake and modification of harmaline in acceptor plants: An innovative approach to visualize the interspecific transfer of natural products

Substances which have been leached out from decomposing plant parts or exuded from vital plants (donor plants), are taken up by acceptor plants and subsequently modified. This phenomenon was likewise established for harmala alkaloids. Employing hydroponically grown barley seedlings, it becomes evident that harmaline and harmine are taken up by the roots of the acceptor plants. Furthermore, based on HPLC and GC-MS analyses, it was demonstrated that these alkaloids also are present in Setaria viridis plants, which grew in the direct vicinity of the alkaloid containing Peganum harmala plants.Since harmaline exhibits a bright green fluorescence, this alkaloid was employed to visualize the uptake into the acceptor plants by feeding it to roots of barley seedlings. In the further course, the imported harmaline was converted in the leaves to yield harmine, which exhibits a dark blue fluorescence. This conversion was also verified by HPLC and GC-MS analyses. Based on the massive differences in the fluorescence properties, both processes, uptake and modification in the acceptor plants, could be monitored by macroscopical studies as well as by confocal laser scanning microscopical analyses. As result, for the first time, the phenomenon of ”Horizontal Natural Product Transfer” is visualized vividly.

Tight DNA-protein complexes isolated from barley seedlings are rich in potential guanine quadruplex sequences.

BackgroundThe concept of chromatin domains attached to the nuclear matrix is being revisited, with nucleus described as a set of topologically associating domains. The significance of the tightly bound to DNA proteins (TBP), a protein group that remains attached to DNA after its deproteinization should be also revisited, as the existence of these interactions is in good agreement with the concept of the topologically associating domain. The work aimed to characterize the DNA component of TBP isolated from barley seedlings.MethodsThe tight DNA-protein complexes from the first leaves, coleoptiles, and roots of barley seedlings were isolated by purification with chromatography on nitrocellulose or exhaustive digestion of DNA with DNase I. Cloning and transformation were performed using pMOSBBlue Blunt Ended Cloning Kit. Inserts were amplified by PCR, and sequencing was performed on the MegaBace 1000 Sequencing System. The BLAST search was performed using sequence databases at NCBI, CR-EST, and TREP and Ensembl Plants databases. Comparison to MAR/SAR sequences was performed using http://smartdb.bioinf.med.uni-goettingen.de/cgi-bin/SMARtDB/smar.cgi database. The prediction of G quadruplexes (GQ) was performed with the aid of R-studio library pqsfinder. CD spectra were recorded on a Chirascan CS/3D spectrometer.ResultsAlthough the barley genome is AT-rich (43% of GC pairs), most DNA fragments associated with TBP were GC-rich (up to 70% in some fractions). Both fractionation procedures yielded a high proportion of CT-motif sequences presented predominantly by the 16-bp CC(TCTCCC)2 TC fragment present in clones derived from the TBP-bound DNA and absent in free DNA. BLAST analysis revealed alignment with different barley repeats. Some clones, however, aligned with both nuclear and chloroplast structural genes. Alignments with MAR/SAR motifs were very few. The analysis produced by the pqsfinder program revealed numerous potential quadruplex-forming sites in the TBP-bound sequences. A set of oligonucleotides containing sites of possible GQs were designed and ordered. Three of them represented the minus strand of the CT-repeat. Two were derived from sequences of two clones of nitrocellulose retained fraction from leaves and contained GC-rich motifs different from the CT motif. Circular dichroism spectroscopy revealed profound changes in spectra when oligonucleotides were incubated with 100 mM KCl. There was either an increase of positive band in the area of 260 nm or the formation of a positive band at 290 nm. In the former case, changes are typical for parallel G-quadruplexes and, in the latter, 3 + 1 structures. DiscussionThe G-quadruplexes anchor proteins are probably involved in the maintenance of the topologically associated domain structure.

Role of the XylA gene, encoding a cell wall degrading enzyme, during common wheat, durum wheat and barley colonization by Fusarium graminearum

Fusarium graminearum is the main causal agent of fusarium head blight (FHB) of wheat and barley. This filamentous fungus is able to produce hydrolytic enzymes, such as xylanases, that cause cell wall degradation, permitting host colonization. This study investigated the role of the F. graminearum XylA (FGSG_10999) gene during infection, using a knockout mutant in strain CS3005. Assays were carried out on common wheat, durum wheat and barley to compare virulence of a XylA knockout to that of wild type strain. These assays were conducted on wheat and barley seedling roots, seedling stem bases and heads. Furthermore, additional in vitro experiments were conducted to investigate the role of XylA gene in the utilisation of D-xylose, the main component of cereals cell wall. In planta assays showed the importance of XylA gene for F. graminearum virulence towards its main hosts. A positive correlation between symptom incidence and fungal biomass development was also observed for both the wild type and the knockout strains. Finally, gene expression studies performed in a liquid medium enriched with D-xylose, a known xylanase inducer in other fungi, showed that the absence of the gene in the FGSG_10999 locus was not compensated by two other F. graminearum xylanase encoding genes analysed (loci FGSG_06445 and FGSG_11478).

Modulation of biochemical and physiological parameters in Hordeum vulgare L. seedlings under the influence of benzyl-butyl phthalate.

BackgroundPhthalates are man-made chemical compounds with numerous applications especially known for their use as plasticizers. They have weak bonding to the polymeric matrix or products in which they are used. Owing to this reason, they are readily released into the environment which makes them ubiquitous. The agricultural soils are also reported to be polluted with phthalates up to a considerable extent which causes adverse effects on flora and fauna. A few studies have been conducted on phthalate-induced phytotoxicity, which has revealed that phthalates affect the quality and yield of edible plants. In the last decades, some crops were analyzed for phthalate-induced adversities; among them, barley was the least explored.MethodsThe present study has investigated the impact of benzyl-butyl phthalate (BBP) on barley (Hordeum vulgare L.) seedlings to address the biochemical, physiological consequences, and toxicological implications. After the exogenous exposure of BBP (viz. 0, 25, 50, 100, 200, 400, 800, 1,600 mg/L) for 7 days, barley seedlings were analyzed for different indices.ResultsThe exposure of BBP mediated a significant (p ≤ 0.05, 0.01) overall elevation in the contents of pigment, proline, soluble protein, carbohydrate, hydrogen peroxide (H2O2), and malondialdehyde (MDA) in shoots and roots of barley seedlings. The activities of superoxide dismutase (SOD), guaiacol peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) were also stimulated significantly in shoots and roots of seedlings against BBP stress except for SOD activity which declined in the roots. The polyphenols (non-enzymatic antioxidants) content was also altered in all the treated concentrations as compared to the control. Furthermore, BBP caused stomatal abnormalities, induced cytotoxicity, and loss of plasma membrane integrity.ConclusionsBBP disturbed the normal physiology of barley which could also affect the yield of the crop under field conditions.

High-mass-resolution MALDI mass spectrometry imaging reveals detailed spatial distribution of metabolites and lipids in roots of barley seedlings in response to salinity stress

IntroductionMass spectrometry imaging (MSI) is a technology that enables the visualization of the spatial distribution of hundreds to thousands of metabolites in the same tissue section simultaneously. Roots are below-ground plant organs that anchor plants to the soil, take up water and nutrients, and sense and respond to external stresses. Physiological responses to salinity are multifaceted and have predominantly been studied using whole plant tissues that cannot resolve plant salinity responses spatially.ObjectivesThis study aimed to use a comprehensive approach to study the spatial distribution and profiles of metabolites, and to quantify the changes in the elemental content in young developing barley seminal roots before and after salinity stress.MethodsHere, we used a combination of liquid chromatography–mass spectrometry (LC–MS), inductively coupled plasma mass spectrometry (ICP–MS), and matrix-assisted laser desorption/ionization (MALDI–MSI) platforms to profile and analyze the spatial distribution of ions, metabolites and lipids across three anatomically different barley root zones before and after a short-term salinity stress (150 mM NaCl).ResultsWe localized, visualized and discriminated compounds in fine detail along longitudinal root sections and compared ion, metabolite, and lipid composition before and after salt stress. Large changes in the phosphatidylcholine (PC) profiles were observed as a response to salt stress with PC 34:n showing an overall reduction in salt treated roots. ICP–MS analysis quantified changes in the elemental content of roots with increases of Na+ and decreases of K+ content.ConclusionOur results established the suitability of combining three mass spectrometry platforms to analyze and map ionic and metabolic responses to salinity stress in plant roots and to elucidate tolerance mechanisms in response to abiotic stress, such as salinity stress.

Boron induces seed germination and seedling growth of Hordeum vulgare L. under Nacl stress

Boron (B), an essential micronutrient, helps the plants to complete their life cycle successfully. Therefore, the present experiment was conducted to study (1) the role of B in seed germination and seedling growth, (2) the toxicity effect of B in seed germination and seedling growth and (3) the role of B in tolerance of barley (Hordeum vulgare L. var. ‘Bakore’) to NaCl stress. Under NaCl stress and non-stress conditions, application of high levels of B (100 µM) decreased parameters of germination (G%, VI, GI and MGT), growth (RL, SL, RFW, SFW, RDW and SDW), except the accumulation of Pro and MDA in barley seedlings. Also, a fluorescence study reveals that production of ROS (H2O2 and O2 •—) and non-viable cells increased in roots of barley seedlings treated with NaCl and high dose of B. An alteration in anatomical structure of barley seedlings was observed with the application of NaCl and high dose of B. However, a low concentration of B (50 µM) proved best and increased all germination and growth traits of barley seedlings by increasing further accumulation of Pro. Also, 50 µM of B significantly increased the biosynthesis of photosynthetic pigments (Chl a, b and total Chl) and deceased formation of ROS and viable cells in roots. Therefore, concluded that sufficient dose of B could be beneficial for barley plant in improving the tolerance to NaCl stress.

Средообразующая активность корневой системы регенерантов ячменя в условиях токсичности кислых почв

Regenerative lines of barley 917-01, 781-04, 441-05, 530-98 obtained by cell selection on acid selective media with aluminum, were evaluated with regard to the original sorts 999-93, Novichok and standard Bios 1 in the laboratory, vegetative and field experiments. The dynamics of changes in the medium acidity by the roots of barley seedlings and their biometric indicators against the control (pH 6.0) and stress (pH 4.0 and pH 4.0 + Al 3+ 20 mg/l) backgrounds were studied in the aquatic culture. Regenerated 917-01 and 781-04 were alkalinizing water actively (by 2.4-2.5 pH units) against the background of intensive root growth compared to the control (43%) and biomass accumulation (10%). The solution acidity of Novichok and its regenerantive genotype 441-05 was changing slightly. In vegetation experiments, the environment-forming activity of the regenerative line 530-98 in changing the acidity and content of free aluminum in the zone of the rhizosphere was studied. On soil background with pH 3.9 and A1 3+ 5.6 mg/100 g of soil the level of alkalization reached 0.7 units of pH at decrease in amount of free aluminum by 4.23 mg / 100 g of soil that 1.8 times exceeded the similar indicators of the standard Bios 1. With stress intensification, the increased productivity of the regenerant relative to the standard up to 2 times was revealed (by 0.66 t/ha on the soil background at pH 3.7 and Al 21 mg/100 g of soil). In favorable conditions of cultivation, the productivity of regenerants decreased relative to the standard. In the competitive tests the regenerative genotypes 917-01 and 530-98, possessing high medium forming activity of the root system, were among the best breeding numbers. Line 917-01 received the status of the sort (the Forward). Not all regenerants possessed breeding value. Selection in vitro of Al- resistant sort Novichok has not led to positive results. The conclusion about expediency of involvement in cellular selection of genotypes with low level of stress resistance and potentially high adaptive variability has been made.

Acid Phosphatases Activity and Growth of Barley, Oat, Rye and Wheat Plants as Affected by Pi Deficiency

Objective: The influence of phosphorus deficit on the growth of plants and acid phosphatases activity in leaves and roots of barley seedlings (Hordeum vulgare L.), as well as oat (Avena sativa L.), rye (Secale cereale L.) and wheat plants (Triticum vulgare L.) was studied. Method: Plants were cultured three weeks in a nutrient media: complete (control, +P) or without phosphorus (-P). The growth on -P medium significantly affected the inorganic phosphate (Pi) content in plants tissues. Pi deficit decreased shoots growth but ratio of root/shoot was higher for -P plants when compared to control. The root elongation was enhanced under Pi deficiency - in -P oat and barley more intensive elongation was observed than in other plants. On the other hand, inhibition of shoot growth was more pronounced for -P rye and wheat. Pi-deficient plants showed higher activity of acid phosphatases in tissue extracts and in exudates from roots than +P plants. Result: Extracellular acid phosphatases activity increased the most for -P rye and wheat plants. Acid phosphatases secretion was intensive in growing parts of Pi-deficient roots. The activity of enzymes secreted by -P roots of all studied plants was higher than intracellular acid phosphatases. Conclusion: Our results indicated that wheat is more sensitive to the Pi deficiency at the early stage of growth than other plants, whereas oat is rather resistant to Pi deficit. The results suggested that acid phosphatases played an important role in acclimation of studied crop plants to moderate Pi deficiency.

Expression analysis of three SERK-like genes in barley under abiotic and biotic stresses

ABSTRACTSomatic embryogenesis receptor-like kinases (SERKs), a subfamily of receptor-like kinases, showed important roles in plant response to abiotic and biotic stresses in addition to embryogenesis and organogenesis in numerous plant species. In the present study, three orthologs of SERK genes (HvSERK1/2/3) were isolated from barley, and their expression patterns during in vitro culture of microspores as well as their responses to different stresses including salinity and powdery mildew were characterized. Sequence analysis suggested that three HvSERK genes were highly conserved in the grass family. Subcellular localization showed the HvSERK1 protein located on the plasma membrane. The HvSERK1 transcript was up-regulated during the microspore culture period, suggesting its roles in microspore embryogenesis. HvSERK1 and HvSERK3 showed the highest expression level in the leaves; however no difference was detected for HvSERK2 expression in different plants’ tissues. Under salt stress, all three HvSERK genes were quickly induced in microspore-derived embryogenic calli, whereas only HvSERK1 was up-regulated in the roots of barley seedlings. Moreover, only HvSERK2 was induced in the barley leaves upon powdery mildew inoculation. These results suggest that barley SERK genes may participate in barley microspores’ development and plant response toward salt and fungal stress, and the function of them has some evolutionary changes.

Plant roots: new challenges in a changing world

Plant roots: new challenges in a changing world

Influence of Merosesquiterpenoids from Marine Sponges on Seedling Root Growth of Agricultural Plants

The impact of the merosesquiterpenoids avarol (1), avarone (2), 18-methylaminoavarone (3), melemeleone A (4), isospongiaquinone (5), ilimaquinone (6), and smenoquinone (7), isolated from marine sponges of the Dictyoceratida order, was studied on the root growth of seedlings of buckwheat (Fagopyrumesculentum Moench), wheat (Triticumaestivum L.), soy (Glycine max (L.) Merr.), and barley (Hordeumvulgare L.). Compounds 2and 6 were effective for the root growth of wheat seedlings, compound 3 stimulated the root growth of seedlings of buckwheat and soy, compound 4 affected the roots of barley seedlings, and compound 5 stimulated the root growth of seedlings of buckwheat and barley. Compounds 1 and 7 showed no activity on the root growth of the seedlings of any of the studied plants. The stimulatory effect depends on the chemical structure of the compounds and the type of crop plant.

Hydrogen sulfide enhances salt tolerance through nitric oxide-mediated maintenance of ion homeostasis in barley seedling roots.

Hydrogen sulfide (H2S) and nitric oxide (NO) are emerging as messenger molecules involved in the modulation of plant physiological processes. Here, we investigated a signalling network involving H2S and NO in salt tolerance pathway of barley. NaHS, a donor of H2S, at a low concentration of either 50 or 100 μM, had significant rescue effects on the 150 mM NaCl-induced inhibition of plant growth and modulated the K+/Na+ balance by decreasing the net K+ efflux and increasing the gene expression of an inward-rectifying potassium channel (HvAKT1) and a high-affinity K+ uptake system (HvHAK4). H2S and NO maintained the lower Na+ content in the cytoplast by increasing the amount of PM H+-ATPase, the transcriptional levels of PM H+-ATPase (HvHA1) and Na+/H+ antiporter (HvSOS1). H2S and NO modulated Na+ compartmentation into the vacuoles with up-regulation of the transcriptional levels of vacuolar Na+/H+ antiporter (HvVNHX2) and H+-ATPase subunit β (HvVHA-β) and increased in the protein expression of vacuolar Na+/H+ antiporter (NHE1). H2S mimicked the effect of sodium nitroprusside (SNP) by increasing NO production, whereas the function was quenched with the addition of NO scavenger. These results indicated that H2S increased salt tolerance by maintaining ion homeostasis, which were mediated by the NO signal.

Cadmium effect on vacuolar H+-ATPase gene expression in the roots of barley seedlings of different age

Expression of two genes (HvVHA E and HvVHA c) of vacuolar H+-ATPase was studied in the cells of barley (Hordeum vulgare L., cv. Zazerskii 85) roots in seedlings of different age in the presence of cadmium (100 μM). Three-day-old seedlings were kept for four days on cadmium solution, which caused suppression of root growth accompanied by an increase in HvVHA E gene expression. In this case, the content of reduced glutathione (GSH) decreased. When seven-day-old seedlings were placed on cadmium solution and kept there for four days, the content of metal in the root was higher, but its growth was not suppressed and expression of both studied genes markedly increased. The content of GSH also apparently increased, ensuring the maintenance of high enzyme activity. A comparison of gene expression encoding two subunits of vacuolar H+-ATPase and cadmium resistance of the seedlings of different age showed that the enzyme participates in the mechanism of the improvement of barley tolerance to this metal.

Vertical gradient in soil temperature stimulates development and increases biomass accumulation in barley

We have detailed knowledge from controlled environment studies on the influence of root temperature on plant performance, growth and morphology. However, in all studies root temperature was kept spatially uniform, which motivated us to test whether a vertical gradient in soil temperature affected development and biomass production. Roots of barley seedlings were exposed to three uniform temperature treatments (10, 15 or 20°C) or to a vertical gradient (20-10°C from top to bottom). Substantial differences in plant performance, biomass production and root architecture occurred in the 30-day-old plants. Shoot and root biomass of plants exposed to vertical temperature gradient increased by 144 respectively, 297%, compared with plants grown at uniform root temperature of 20°C. Additionally the root system was concentrated in the upper 10cm of the soil substrate (98% of total root biomass) in contrast to plants grown at uniform soil temperature of 20°C (86% of total root biomass). N and C concentrations in plant roots grown in the gradient were significantly lower than under uniform growth conditions. These results are important for the transferability of 'normal' greenhouse experiments where generally soil temperature is not controlled or monitored and open a new path to better understand and experimentally assess root-shoot interactions.

Protein carbonylation in barley seedling roots caused by aluminum and proton toxicity is suppressed by salicylic acid

Proton (H+) and aluminum (Al3+) toxicities are major factors limiting crop production on acid soils. To study whether salicylic acid (SA) is functional in alleviating protein damage caused by H+ and Al3+ toxicities, an investigation of the antioxidant defense response regulated by SA was carried out on barley (Hordeum vulgare L.) seedlings under H+, Al3+, and combined stresses. It was found that the relative root elongation of seedlings, which grew in the solutions supplemented with SA, was significantly higher than that of seedlings without SA treatment after 24-h treatments with H+, Al3+, and combined stresses. The lesser amount of carbonylated proteins with molecular weights ranging from 14.4 to 97 kD, was accumulated in seedlings treated with SA than that in the seedlings without SA treatment. The higher activities of antioxidant enzymes and lesser content of MDA were observed in seedlings treated with SA compared with the seedlings without SA treatment. Moreover, the nitroblue tetrazolium staining of roots showed that ROS accumulation was decreased by SA treatments. This study suggested that SA could alleviate cell damage caused by H+ and Al3+ toxicities on acid soils by both activating antioxidant defense responses and reducing the contents of carbonylated proteins caused by ROS in barley seedlings.