for Journals by Title or ISSN
for Articles by Keywords
help

Publisher: Elsevier   (Total: 2566 journals)

 A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z  

  First | 19 20 21 22 23 24 25 26     

The end of the list has been reached. Please navigate to previous pages.

  First | 19 20 21 22 23 24 25 26     

Journal Cover Plant Physiology and Biochemistry
   Journal TOC RSS feeds Export to Zotero [11 followers]  Follow    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 0981-9428
     Published by Elsevier Homepage  [2566 journals]   [SJR: 0.996]   [H-I: 63]
  • Foliar potassium nitrate application improves the tolerance of Citrus
           macrophylla L. seedlings to drought conditions
    • Abstract: Publication date: October 2014
      Source:Plant Physiology and Biochemistry, Volume 83
      Author(s): V. Gimeno , L. Díaz-López , S. Simón-Grao , V. Martínez , J.J. Martínez-Nicolás , F. García-Sánchez
      Scarcity of water is a severe limitation in citrus tree productivity. There are few studies that consider how to manage nitrogen (N) nutrition in crops suffering water deficit. A pot experiment under controlled-environment chambers was conducted to explore if additional N supply via foliar application could improve the drought tolerance of Citrus macrophylla L. seedlings under dry conditions. Two-month-old seedlings were subjected to a completely random design with two water treatments (drought stress and 100% water/field capacity). Plants under drought stress (DS) received three different N supplies via foliar application (DS: 0, DS + NH4NO3: 2% NH4NO3, DS + KNO3: 2% KNO3). KNO3-spraying increased leaf and stem DW as compared with DS + NH4NO3 and DS treatments. Leaf water potential (Ψ w) was decreased by drought stress in all the treatments. However, in plants from DS + NH4NO and DS + KNO3, this was due to a decrease in the leaf osmotic potential, whereas the decrease in those from the DS treatment was due to a decrease in the leaf turgor potential. These responses were correlated with the leaf proline and K concentrations. DS + KNO3-treated plants had a higher leaf proline and K concentration than DS-treated plants. In terms of leaf gas exchange parameters, it was observed that net assimilation of CO2 ( A CO 2 ) was decreased by drought stress, but this reduction was much lower in DS + KNO3-treated plants. Thus, when all results are taken into account, it can be concluded that a 2% foliar-KNO3 application can enhance the tolerance of citrus plants to water stress by increasing the osmotic adjustment process.
      Graphical abstract image

      PubDate: 2014-09-16T07:55:26Z
       
  • Dual effects of different selenium species on wheat
    • Abstract: Publication date: October 2014
      Source:Plant Physiology and Biochemistry, Volume 83
      Author(s): B. Guerrero , M. Llugany , O. Palacios , M. Valiente
      Wheat (Triticum aestivum) and its derivative products account for a major source of dietary intake of selenium (Se) in humans and animals, because of its essentiality due to its presence in vital enzymes. Se antioxidant role has resulted in the popularity of agronomic biofortification practises in Se deficient areas. Controlling Se uptake, metabolism, translocation and accumulation in plants will be important to decrease healthy risk of toxicity and deficiency and to help selecting adequate methods for biofortification. Selenate and selenite are the two main inorganic Se forms available in soil and in most of the studies are given separately. That study reveals that both Se species behave differently but combined the prevalent pattern is that of selenite; so it is taken up faster and it seems that interferes with selenate uptake and transport. Selenium has dual effects on wheat plants; at low concentrations it acts as growth stimulant whereas at high concentrations it reduces root elongation and biomass production and alters uptake and translocation of several essential nutrients.


      PubDate: 2014-09-11T22:33:12Z
       
  • Influence of silicon on maize roots exposed to antimony – Growth and
           antioxidative response
    • Abstract: Publication date: October 2014
      Source:Plant Physiology and Biochemistry, Volume 83
      Author(s): Miroslava Vaculíková , Marek Vaculík , Lenka Šimková , Ivana Fialová , Zuzana Kochanová , Barbora Sedláková , Miroslava Luxová
      Pollution of antimony (Sb) raises a serious environmental problem. Although this non-essential element can be taken up by roots and accumulated in plant tissues in relatively high concentrations, there is still lack of knowledge about the effect of Sb on biochemical and metabolic processes in plants. It was shown that application of silicon (Si) can decrease the toxicity of other heavy metals and toxic elements in various plants. The aim of this study was to assess how Si influences the growth and antioxidative response of young Zea mays L. roots exposed to elevated concentrations of Sb. Antimony reduced the root growth and induced oxidative stress and activated antioxidant defense mechanisms in maize. Silicon addition to Sb treated roots decreased oxidative stress symptoms documented by lower lipid peroxidation, proline accumulation, and decreased activity of antioxidative enzymes (ascorbate peroxidase, EC 1.11.1.11; catalase, EC 1.11.1.6; and guaiacol peroxidase, EC 1.11.1.7). Although neither positive nor negative effect of Si has been observed on root length and biomass, changes in the oxidative response of plants exposed to Sb indicate a possible mitigation role of Si on Sb toxicity in plants.


      PubDate: 2014-09-11T22:33:12Z
       
  • Cytokinin producing bacteria stimulate amino acid deposition by wheat
           roots
    • Abstract: Publication date: October 2014
      Source:Plant Physiology and Biochemistry, Volume 83
      Author(s): Guzel R. Kudoyarova , Alexander I. Melentiev , Elena V. Martynenko , Leila N. Timergalina , Tatiana N. Arkhipova , Galina V. Shendel , Ludmila Yu Kuz'mina , Ian C. Dodd , Stanislav Yu Veselov
      Phytohormone production is one mechanism by which rhizobacteria can stimulate plant growth, but it is not clear whether the bacteria gain from this mechanism. The hypothesis that microbial-derived cytokinin phytohormones stimulate root exudation of amino acids was tested. The rhizosphere of wheat plants was drenched with the synthetic cytokinin trans-zeatin or inoculated with Bacillus subtilis IB-22 (which produces zeatin type cytokinins) or B. subtilis IB-21 (which failed to accumulate cytokinins). Growing plants in a split root system allowed spatial separation of zeatin application or rhizobacterial inoculation to one compartment and analyses of amino acid release from roots (rhizodeposition) into the other compartment (without either microbial inoculation or treatment with exogenous hormone). Supplying B. subtilis IB-22 or zeatin to either the whole root system or half of the roots increased concentrations of amino acids in the soil solution although the magnitude of the increase was greater when whole roots were treated. There was some similarity in amino acid concentrations induced by either bacterial or zeatin treatment. Thus B. subtilis IB-22 increased amino acid rhizodeposition, likely due to its ability to produce cytokinins. Furthermore, B. subtilis strain IB-21, which failed to accumulate cytokinins in culture media, did not significantly affect amino acid concentrations in the wheat rhizosphere. The ability of rhizobacteria to produce cytokinins and thereby stimulate rhizodeposition may be important in enhancing rhizobacterial colonization of the rhizoplane.


      PubDate: 2014-09-11T22:33:12Z
       
  • Identification of two highly specific pollen promoters using
           transcriptomic data
    • Abstract: Publication date: October 2014
      Source:Plant Physiology and Biochemistry, Volume 83
      Author(s): Daniela Muñoz-Strale , Gabriel León
      The mature pollen grain displays a highly specialized function in angiosperms. Accordingly, the male gametophyte development involves many specific biological activities, making it a complex and unique process in plants. In order to accomplish this, during pollen development, a massive transcriptomic remodeling takes place, indicating the switch from a sporophytic to a gametophytic program and involving the expression of many pollen specific genes. Using microarray databases we selected genes showing pollen-specific accumulation of their mRNAs and confirmed this through RT-PCR. We selected five genes (POLLEN SPECIFIC GENE1-5) to investigate the pollen specificity of their expression. Transcriptional fusions between the putative promoters of these genes and the uidA reporter gene in Arabidopsis confirmed the pollen specific expression for at least two of these genes. The expression of the cytotoxin Barnase controlled by these promoters generated pollen specific ablation and male sterility. Through the selection of pollen specific genes from public datasets, we were able to identify promoter regions that confer pollen expression. The use of the cytotoxin Barnase allowed us to demonstrate its expression is exclusively limited to the pollen. These new promoters provide a powerful tool for the expression of genes exclusively in pollen.


      PubDate: 2014-09-11T22:33:12Z
       
  • Comparison of a compatible and an incompatible pepper-tobamovirus
           interaction by biochemical and non-invasive techniques: Chlorophyll a
           fluorescence, isothermal calorimetry and FT-Raman spectroscopy
    • Abstract: Publication date: October 2014
      Source:Plant Physiology and Biochemistry, Volume 83
      Author(s): Magdalena Rys , Csilla Juhász , Ewa Surówka , Anna Janeczko , Diana Saja , István Tóbiás , Andrzej Skoczowski , Balázs Barna , Gábor Gullner
      Leaves of a pepper cultivar harboring the L 3 resistance gene were inoculated with Obuda pepper virus (ObPV), which led to the appearance of hypersensitive necrotic lesions approx. 72 h post-inoculation (hpi) (incompatible interaction), or with Pepper mild mottle virus (PMMoV) that caused no visible symptoms on the inoculated leaves (compatible interaction). ObPV inoculation of leaves resulted in ion leakage already 18 hpi, up-regulation of a pepper carotenoid cleavage dioxygenase (CCD) gene from 24 hpi, heat emission and declining chlorophyll a content from 48 hpi, and partial desiccation from 72 hpi. After the appearance of necrotic lesions a strong inhibition of photochemical energy conversion was observed, which led to photochemically inactive leaf areas 96 hpi. However, leaf tissues adjacent to these inactive areas showed elevated ΦPSII and Fv/Fm values proving the advantage of chlorophyll a imaging technique. PMMoV inoculation also led to a significant rise of ion leakage and heat emission, to the up-regulation of the pepper CCD gene as well as to decreased PSII efficiency, but these responses were much weaker than in the case of ObPV inoculation. Chlorophyll b and total carotenoid contents as measured by spectrophotometric methods were not significantly influenced by any virus inoculations when these pigment contents were calculated on leaf surface basis. On the other hand, near-infrared FT-Raman spectroscopy showed an increase of carotenoid content in ObPV-inoculated leaves suggesting that the two techniques detect different sets of compounds.


      PubDate: 2014-09-11T22:33:12Z
       
  • Identification of a new sucrose transporter in rye-grass (LpSUT2): Effect
           of defoliation and putative fructose sensing
    • Abstract: Publication date: Available online 9 September 2014
      Source:Plant Physiology and Biochemistry
      Author(s): Alexandre Berthier , Frédéric Meuriot , Fabienne Dédaldéchamp , Rémi Lemoine , Marie-Pascale Prud’homme , Nathalie Noiraud-Romy
      Rye-grass fast regrowth after defoliation results from an efficient mobilization of C reserves which are transported as sucrose towards regrowing leaves, and which can be supported by one or several sucrose transporters (SUTs) like LpSUT1. Therefore, our objectives were to isolate, identify, characterize and immunolocalize such sucrose transporters. A protein (LpSUT2) showing a twelve spanning trans-membrane domain, extended N terminal and internal cytoplasmic loop, and kinetic properties consistent with well-known sucrose transporters, was isolated and successfully characterized. Along with LpSUT1, it was mainly localized in mesophyll cells of leaf sheaths and elongating leaf bases. These transporters were also found in parenchyma bundle sheath (PBS) cells but they were not detected in the sieve element/companion cell complex of the phloem. Unlike LpSUT1 transcript levels which increased as a response to defoliation in source and sink tissues, LpSUT2 transcript levels were unaffected by defoliation and weakly expressed. Interestingly, sucrose transport by LpSUT2 was inhibited by fructose. LpSUT1 and LpSUT2 appeared to have different functions. LpSUT1 is proposed to play a key role in C storage and mobilization by allowing sucrose transport between PBS and mesophyll cells, depending on the plant C status. LpSUT2 could be involved in sucrose/fructose sensing at sub-cellular level.


      PubDate: 2014-09-11T22:33:12Z
       
  • In vivo Assessment of Effect of Phytotoxin Tenuazonic Acid on PSII
           Reaction Centers
    • Abstract: Publication date: Available online 10 September 2014
      Source:Plant Physiology and Biochemistry
      Author(s): Shiguo Chen , Reto Jörg Strasser , Sheng Qiang
      Tenuazonic acid (TeA), a phytotoxin produced by the fungus Alternaria alternata isolated from diseased croftonweed (Ageratina adenophora), exhibits a strong inhibition in photosystem II (PSII) activity. In vivo the chlorophyll fluorescence transients of the host plant croftonweed, show that the dominant effect of TeA is not on the primary photochemical reaction but on the biochemical reaction after QA. The most important action site of TeA is the QB site on the PSII electron-acceptor side, blocking electron transport beyond QA - by occupying the QB site in the D1 protein. However, TeA does not affect the antenna pigments, the energy transfer from antenna pigment molecules to reaction centers (RCs), and the oxygen-evolving complex (OEC) at the donor side of PSII. In the case of TeA, severe inactivation of PSII RCs occurred. The fraction of non-QA reducing centers and non-QB reducing centers show a time- and concentration-dependent linear increase. Conversely, the amount of active QA or QB reducing centers declined sharply in a linear way. The fraction of non-QB reducing centers calculated by data of fluorescence transients is close to the number of PSII RCs with their QB site filled by TeA. An increase of the step-J level (VJ) in the OJIP fluorescence transients attributed to QA - accumulation due to TeA bound to the QB site is a typical characteristic response of the plants leaf with respect to TeA penetration.


      PubDate: 2014-09-11T22:33:12Z
       
  • Pb-induced responses in Zygophyllum fabago plants are organ-dependent and
           modulated by salicylic acid
    • Abstract: Publication date: Available online 10 September 2014
      Source:Plant Physiology and Biochemistry
      Author(s): Antonio López-Orenes , Ascensión Martínez-Pérez , Antonio A. Calderón , María A. Ferrer
      Zygophyllum fabago is a promising species for restoring heavy metal (HM) polluted soils, although the mechanisms involved in HM tolerance in this non-model plant remain largely unknown. This paper analyses the extent to which redox-active compounds and enzymatic antioxidants in roots, stems and leaves are responsible for Pb tolerance in a metallicolous ecotype of Z. fabago and the possible influence of salicylic acid (SA) pretreatment (24 h, 0.5 mM SA) in the response to Pb stress. SA pretreatment reduced both the accumulation of Pb in roots and even more so the concentration of Pb in aerial parts of the plants, although a similar drop in the content of chlorophylls and in the maximum quantum yield of photosystem II was observed in both Pb- and SA-Pb-treated plants. Pb increased the endogenous free SA levels in all organs and this response was enhanced in root tissues upon SA pretreatment. Generally, Pb induced a reduction in catalase, ascorbate peroxidase and glutathione reductase specific activities, whereas dehydroascorbate reductase was increased in all organs of control plants. SA pretreatment enhanced the Pb-induced H2O2 accumulation in roots by up-regulating Fe-superoxide dismutase isoenzymes. Under Pb stress, the GSH redox ratio remained highly reduced in all organs while the ascorbic acid redox ratio dropped in leaf tissues where a rise in lipid peroxidation products and electrolyte leakage was observed. Finally, an organ-dependent accumulation of proline and β-carboline alkaloids was found, suggesting these nitrogen-redox-active compounds could play a role in the adaptation strategies of this species to Pb stress.


      PubDate: 2014-09-11T22:33:12Z
       
  • The induction of menadione stress tolerance in the marine microalga,
           Dunaliella viridis, through cold pretreatment and modulation of the
           ascorbate and glutathione pools
    • Abstract: Publication date: Available online 6 September 2014
      Source:Plant Physiology and Biochemistry
      Author(s): Maryam Madadkar Haghjou , Louise Colville , Nicholas Smirnoff
      The effect of cold pretreatment on menadione tolerance was investigated in the cells of the marine microalga, Dunaliella viridis. In addition, the involvement of ascorbate and glutathione in the response to menadione stress was tested by treating cell suspensions with L-galactono-1,4-lactone, an ascorbate precursor, and buthionine sulfoximine, an inhibitor of glutathione synthesis. Menadione was highly toxic to non cold-pretreated cells, and caused a large decrease in cell number. Cold pretreatment alleviated menadione toxicity and cold pretreated cells accumulated lower levels of reactive oxygen species, and had enhanced antioxidant capacity due to increased levels of β-carotene, reduced ascorbate and total glutathione compared to non cold-pretreated cells. Cold pretreatment also altered the response to L-galactono-1,4-lactone and buthionine sulfoximine treatments. Combined L-galactono-1,4-lactone and menadione treatment was lethal in non-cold pretreated cells, but in cold-pretreated cells it had a positive effect on cell numbers compared to menadione alone. Overall, exposure of Dunaliella cells to cold stress enhanced tolerance to subsequent oxidative stress induced by menadione.


      PubDate: 2014-09-11T22:33:12Z
       
  • Transgenic alfalfa plants expressing AtNDPK2 exhibit increased growth and
           tolerance to abiotic stresses
    • Abstract: Publication date: Available online 6 September 2014
      Source:Plant Physiology and Biochemistry
      Author(s): Zhi Wang , Hongbing Li , Qingbo Ke , Jae Cheol Jeong , Haeng-Soon Lee , Bingcheng Xu , Xi-Ping Deng , Yongpyo Lim , Sang-Soo Kwak
      In this study, we generated and evaluated transgenic alfalfa plants (Medicago sativa L. cv. Xinjiang Daye) expressing the Arabidopsis nucleoside diphosphate kinase 2 (AtNDPK2) gene under the control of the oxidative stress-inducible SWPA2 promoter (referred to as SN plants) to develop plants with enhanced tolerance to various abiotic stresses. We selected two SN plants (SN4 and SN7) according to the expression levels of AtNDPK2 and the enzyme activity of NDPK in response to methyl viologen (MV)-mediated oxidative stress treatment using leaf discs for further characterization. SN plants showed enhanced tolerance to high temperature, NaCl, and drought stress on the whole-plant level. When the plants were subjected to high temperature treatment (42°C for 24 h), the non-transgenic (NT) plants were severely wilted, whereas the SN plants were not affected because they maintained high relative water and chlorophyll contents. The SN plants also showed significantly higher tolerance to 250 mM NaCl and water stress treatment than the NT plants. In addition, the SN plants exhibited better plant growth through increased expression of auxin-related indole acetic acid (IAA) genes (MsIAA3, MsIAA5, MsIAA6, MsIAA7, and MsIAA16) under normal growth conditions compared to NT plants. The results suggest that induced overexpression of AtNDPK2 in alfalfa will be useful for increasing biomass production under various abiotic stress conditions.


      PubDate: 2014-09-11T22:33:12Z
       
  • Metabolomic insights into the bioconversion of isonitrosoacetophenone in
           Arabidopsis thaliana and its effects on defense-related pathways
    • Abstract: Publication date: Available online 6 September 2014
      Source:Plant Physiology and Biochemistry
      Author(s): Ntakadzeni E. Madala , Paul A. Steenkamp , Lizelle A. Piater , Ian A. Dubery
      Plants are constantly exposed to numerous biotic or abiotic stress factors throughout their life-cycle. Pathogens and pathogen-derived molecules are the best studied inducers of plant defense responses, but synthetic and naturally occurring molecules have also been used to induce various types of resistance in plants. Here, an oxime molecule, 2-isonitrosoacetophenone (INAP), related to the stress metabolite citaldoxime, was used to trigger metabolic changes in the metabolome of treated Arabidopsis thaliana plants as monitored by UHPLC–MS in conjunction with principal component analysis (PCA) and orthogonal projection to latent structures discriminant analysis (OPLS-DA). The chemometric methods revealed metabolites found to be significantly present in response to the treatment. These include bioconversion products (2-keto-2-phenylacetaldoxime-glycoside and l-mandelonitrile-glycoside) as well as those of which the levels are affected by the treatment (benzoic acid and derivatives, other phenylpropanoid-derived compounds and glucosinolates). Using in planta bacterial growth evaluations, INAP treatment was furthermore found to induce an anti-microbial environment in vivo.
      Graphical abstract image

      PubDate: 2014-09-11T22:33:12Z
       
  • Phytotoxic action of naphthoquinone juglone demonstrated on lettuce
           seedling roots
    • Abstract: Publication date: Available online 11 September 2014
      Source:Plant Physiology and Biochemistry
      Author(s): Petr Babula , Veronika Vaverkova , Zuzana Poborilova , Ludmila Ballova , Michal Masarik , Ivo Provaznik
      Juglone, 5-hydroxy-1,4-naphthoquinone, is the plant secondary metabolite with allelopathic properties, which was isolated especially from the plant species belonging to family Juglandaceae A. Rich. ex Kunth (walnut family). The mechanism of phytotoxic action of juglone was investigated on lettuce seedlings Lactuca sativa L. var. capitata L. cv. Merkurion by determining its effect at different levels. We have found that juglone inhibits mitosis (mitotic index 8.5±0.6 % for control versus 2.2±0.9 % for 250 μM juglone), changes mitotic phase index with accumulation of the cells in prophase (56.5±2.6 % for control versus 85.3±5.0 % for 250 μM juglone), and decreases meristematic activity in lettuce root tips (51.07±3.62 % for control versus 5.27±2.29 % for 250 μM juglone). In addition, juglone induced creation of reactive oxygen species and changed levels of reactive nitrogen species. Amount of malondialdehyde, a product of lipid peroxidation, increased from 24.0±4.0 ng.g-1 FW for control to 55.5±5.4 ng.g-1 FW for 250 μM juglone. We observed also changes in cellular structure, especially changes in the morphology of endoplasmic reticulum. Reactive oxygen species induced damage of plasma membrane. All these changes resulted in the disruption of the mitochondrial membrane potential, increase in free intracellular calcium ions, and DNA fragmentation and programmed cell death that was revealed by two methods, TUNEL test and DNA electrophoresis. The portion of TUNEL-positive cells increase from 0.96±0.5 % for control to 7.66±1.5 % for 250 μM juglone. Results of the study indicate complex mechanism of phytotoxic effect of juglone in lettuce root tips and may indicate mechanism of allelopathic activity of this compound.


      PubDate: 2014-09-11T22:33:12Z
       
  • Physiological and molecular responses to drought stress in rubber tree
           (Hevea brasiliensis Muell. Arg.)
    • Abstract: Publication date: October 2014
      Source:Plant Physiology and Biochemistry, Volume 83
      Author(s): Li-feng Wang
      Plant drought stress response and tolerance are complex biological processes. In order to reveal the drought tolerance mechanism in rubber tree, physiological responses and expressions of genes involved in energy biosynthesis and reactive oxygen species (ROS) scavenging were systematically analyzed following drought stress treatment. Results showed that relative water content (RWC) in leaves was continuously decreased with the severity of drought stress. Wilting leaves were observed at 7 day without water (dww). Total chlorophyll content was increased at 1 dww, but decreased from 3 dww. However, the contents of malondialdehyde (MDA) and proline were significantly increased under drought stress. Peroxidase (POD) and superoxide dismutase (SOD) activities were markedly enhanced at 1 and 3 dww, respectively. Meanwhile, the soluble sugar content was constant under drought stress. These indicated that photosynthetic activity and membrane lipid integrity were quickly attenuated by drought stress in rubber tree, and osmoregulation participated in drought tolerance mechanism in rubber tree. Expressions of energy biosynthesis and ROS scavenging systems related genes, including HbCuZnSOD, HbMnSOD, HbAPX, HbCAT, HbCOA, HbATP, and HbACAT demonstrated that these genes were significantly up-regulated by drought stress, and reached a maximum at 3 dww, then followed by a decrease from 5 dww. These results suggested that drought stress adaption in rubber tree was governed by energy biosynthesis, antioxidative enzymes, and osmoregulation.


      PubDate: 2014-09-05T21:59:15Z
       
  • Cloning and characterization of an elicitor-responsive gene encoding
           3-hydroxy-3-methylglutaryl coenzyme A reductase involved in
           20-hydroxyecdysone production in cell cultures of Cyanotis arachnoidea
    • Abstract: Publication date: Available online 2 September 2014
      Source:Plant Physiology and Biochemistry
      Author(s): Qiu Jun Wang , Li Ping Zheng , Pei Fei Zhao , Yi Lu Zhao , Jian Wen Wang
      Cyanotis arachnoidea contains a rich source of bioactive phytoecdysteroids (i.e. analogues of insect steroid hormones). 3-Hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) supplies mevalonate for the synthesis of many secondary metabolites including 20-hydroxyecdysone (20E), one of metabolism-enhancing phytoecdysteroids. In this study, in order to develop a sustainable source of 20E, cell suspension cultures were established from shoot cultures of C. arachnoidea, and a full length cDNA encoding HMGR (designated as CaHMGR) was cloned and characterized. The cDNA contained 2037 nucleotides with a complete open reading frame (ORF) of 1800 nucleotides, which was predicted to encode a peptide of 599 amino acids. Expression analysis by real-time PCR revealed that CaHMGR mRNA was abundant in C. arachnoidea stems, roots and leaves. When cultivated in Murashige & Skoog medium supplemented with 0.2 mg L−1 1-naphthlcetic acid (NAA) and 3.0 mg L−1 6-benzyladenine (6-BA), C. arachnoidea cells in suspension culture grew rapidly, yielding 20E (124.14 μg L−1) after 12 days. The content of 20E in cell cultures elicited by 0.2 mM methyl jasmonate (MeJA), 100 mg L−1 yeast elicitor (YE) or 25 μM AgNO3 was increased 8-, 2-, and 6-fold over the control, respectively. Quantitative real-time PCR analysis showed that CaHMGR was expressed at a higher level under the treatment of MeJA or Ag+ elicitor. Our results suggested that 20E accumulation may be the result of the expression up-regulation of CaHMGR involved in the biosynthesis under the treatment of various elicitors.
      Graphical abstract image

      PubDate: 2014-09-05T21:59:15Z
       
  • Effects of molybdenum on water utilization, antioxidative defense system
           and osmotic-adjustment ability in winter wheat (Triticum aestivum)
           under drought stress
    • Abstract: Publication date: Available online 2 September 2014
      Source:Plant Physiology and Biochemistry
      Author(s): Songwei Wu , Chengxiao Hu , Qiling Tan , Zhaojun Nie , Xuecheng Sun
      Molybdenum (Mo), as an essential trace element in plants, plays an essential role in abiotic stress tolerance of plants. To obtain a better understanding of drought tolerance enhanced by Mo, a hydroponic trial was conducted to investigate the effects of Mo on water utilization, antioxidant enzymes, non-enzymatic antioxidants, and osmotic-adjustment products in the Mo-efficient ‘97003’ and Mo-inefficient ‘97014’ under PEG simulated drought stress. Our results indicate that Mo application significantly enhanced P n , chlorophyll, dry matter, grain yield, biomass, RWC and WUE and decreased T r , G s and water loss of wheat under drought stress, suggesting that Mo application improved the water utilization capacity in wheat. The activities of antioxidant enzymes such as superoxide dismutase, peroxidase, catalase, ascorbate peroxidase and the contents of non-enzymatic antioxidants content such as ascorbic acid, reduced glutathione, carotenoid were significantly increased and malonaldehyde contents were decreased by Mo application under PEG simulated drought stress, suggesting that Mo application enhanced the ability of scavenging active oxygen species. The osmotic-adjustment products such as soluble protein, proline and soluble sugar were also increased by Mo application under PEG simulated drought stress, indicating that Mo improved the osmotic adjustment ability in wheat. It is hypothesized that Mo application might improve the drought tolerance of wheat by enhancing water utilization capability and the abilities of antioxidative defense and osmotic adjustment. Similarities and differences between the Mo-efficient and Mo-inefficient cultivars wheat in response to Mo under drought stress are discussed.


      PubDate: 2014-09-05T21:59:15Z
       
  • Evaluation of the anti-nitrative effect of plant antioxidants using a
           cowpea Fe-superoxide dismutase as a target
    • Abstract: Publication date: Available online 2 September 2014
      Source:Plant Physiology and Biochemistry
      Author(s): Estibaliz Urarte , Aaron C. Asensio , Edurne Tellechea , Laura Pires , Jose F. Moran
      Nitric oxide cytotoxicity arises from its rapid conversion to peroxynitrite (ONOO−) in the presence of superoxide, provoking functional changes in proteins by nitration of tyrosine residues. The physiological significance of this post-translational modification is associated to tissue injury in animals, but has not been yet clarified in plants. The objective of this study was to establish new approaches that could help to understand ONOO− reactivity in plants. A recombinant Fe-superoxide dismutase from cowpea (Vigna unguiculata (L.) Walp.), rVuFeSOD, was the target of the ONOO−-generator SIN-1, and the anti-nitrative effect of plant antioxidants and haemoglobins was tested in vitro. Nitration on rVuFeSOD was evaluated immunochemically or as the loss of its enzymatic activity. This assay proved to be useful to test a variety of plant compounds for anti-nitrative capacity. Experimental data confirmed that rice (Oryza sativa L.) haemoglobin-1 (rOsHbI) and cowpea leghaemoglobin-2 exerted a protective function against ONOO− by diminishing nitration on rVuFeSOD. Both plant haemoglobins were nitrated by SIN-1. The chelator desferrioxamine suppressed nitration in rOsHbI, indicating that Fe plays a key role in the reaction. The removal of the haem moiety in rOsHbI importantly suppressed nitration, evidencing that this reaction may be self-catalyzed. Among small antioxidants, ascorbate remarkably decreased nitration in all tests. The phenolic compounds caffeic acid, gallic acid, pyrogallol, 4-hydroxybenzoic acid and the flavonoid gossypin also diminished tyrosine nitration and protected rVuFeSOD to different extents. It is concluded that small plant antioxidants, especially ascorbate and haemoglobins may well play key roles in ONOO− homeostasis in vivo.
      Graphical abstract image

      PubDate: 2014-09-05T21:59:15Z
       
  • Phosphoproteome and proteome analyses reveal low-phosphate mediated
           plasticity of root developmental and metabolic regulation in maize (Zea
           mays L.)
    • Abstract: Publication date: October 2014
      Source:Plant Physiology and Biochemistry, Volume 83
      Author(s): Kunpeng Li , Changzheng Xu , Wenming Fan , Hongli Zhang , Jiajia Hou , Aifang Yang , Kewei Zhang
      Phosphate (Pi) deficiency has become a significant challenge to worldwide agriculture due to the depletion of accessible rock phosphate that is the major source of cheap Pi fertilizers. Previous research has identified a number of diverse adaptive responses to Pi starvation in the roots of higher plants. In this study, we found that accelerated axile root elongation of Pi-deprived maize plants resulted from enhanced cell proliferation. Comparative phosphoproteome and proteome profiles of maize axile roots were conducted in four stages in response to Pi deficiency by multiplex staining of high-resolution two dimensional gel separated proteins. Pro-Q DPS stained gels revealed that 6% of phosphoprotein spots displayed changes in phosphorylation state following low-Pi treatment. These proteins were involved in a large number of metabolic and cellular pathways including carbon metabolism and signal transduction. Changes in protein abundance of a number of enzymes indicated that low-Pi induced a number of carbon flux modifications in metabolic processes including sucrose breakdown and other downstream sugar metabolic pathways. A few key metabolic enzymes, including sucrose synthase (EC 2.4.1.13) and malate dehydrogenase (EC 1.1.1.37), and several signaling components involved in protein kinase or phosphatase cascades, auxin signaling and 14-3-3 proteins displayed low-Pi responsive changes in phosphorylation state or protein abundance. A variety of key enzymes and signaling components identified as potential targets for phosphorylation provide novel clues for comprehensive understanding of Pi regulation in plants. Protein phosphorylation, coordinating with changes in protein abundance, is required for maize root metabolic regulation and developmental acclimation to Pi starvation.


      PubDate: 2014-09-05T21:59:15Z
       
  • An exogenous source of nitric oxide modulates zinc nutritional status in
           wheat plants
    • Abstract: Publication date: Available online 2 September 2014
      Source:Plant Physiology and Biochemistry
      Author(s): Agustina Buet , Jorge I. Moriconi , Guillermo E. Santa-María , Marcela Simontacchi
      The effect of addition of the nitric oxide donor S-nitrosoglutathione (GSNO) on the Zn nutritional status was evaluated in hydroponically-cultured wheat plants (Triticum aestivum cv. Chinese Spring). Addition of GSNO in Zn-deprived plants did not modify biomass accumulation but accelerated leaf senescence in a mode concomitant with accelerated decrease of Zn allocation to shoots. In well-supplied plants, Zn concentration in both roots and shoots declined due to long term exposure to GSNO. A further evaluation of net Zn uptake rate (ZnNUR) during the recovery of long-term Zn-deprivation unveiled that enhanced Zn-accumulation was partially blocked when GSNO was present in the uptake medium. This effect on uptake was mainly associated with a change of Zn translocation to shoots. Our results suggest a role for GSNO in the modulation of Zn uptake and in root-to-shoot translocation during the transition from deficient to sufficient levels of Zn-supply.


      PubDate: 2014-09-05T21:59:15Z
       
  • Nitric oxide, as a downstream signal, plays vital role in auxin induced
           cucumber tolerance to sodic alkaline stress
    • Abstract: Publication date: October 2014
      Source:Plant Physiology and Biochemistry, Volume 83
      Author(s): Biao Gong , Li Miao , Wenjie Kong , Ji-Gang Bai , Xiufeng Wang , Min Wei , Qinghua Shi
      Nitric oxide (NO) and auxin (indole-3-acetic acid; IAA) play vital roles in regulating plants tolerance to abiotic stresses. This study showed that both NO and IAA could induce cucumber plants tolerance to sodic alkaline stress, which depended on their roles in regulating reactive oxygen species (ROS) scavenging, antioxidative enzymes activities, Na+ accumulation and protecting photosystems II (PSII) from damage. In addition, IAA has significant effect on NO accumulation in cucumber root, which could be responsible for IAA-induced sodic alkaline stress tolerance. Further investigation indicated that the function of IAA could be abolished by NO scavenger (cPTIO). On the contrary, IAA transport inhibitor (NPA) showed no significant effects on abolishing the function of NO. Based on these results, it could be concluded that NO is an essential downstream signal for IAA-induced cucumber tolerance to sodic alkaline stress.


      PubDate: 2014-09-05T21:59:15Z
       
  • Group 5 LEA protein, ZmLEA5C, enhance tolerance to osmotic and low
           temperature stresses in transgenic tobacco and yeast
    • Abstract: Publication date: Available online 4 September 2014
      Source:Plant Physiology and Biochemistry
      Author(s): Yang Liu , Li Wang , Shanshan Jiang , Jiaowen Pan , Guohua Cai , Dequan Li
      Group 5 LEA (Late Embryogenesis Abundant) proteins contain a significantly higher proportion of hydrophobic residues but lack significant signature motifs or consensus sequences. This group is considered as an atypical group of LEA proteins. Up to now, there is little known about group 5C LEA proteins in maize. Here, we identified a novel group 5C LEA protein from maize. The accumulation of transcripts demonstrated that ZmLEA5C displayed similar induced characteristics in leaves and roots. Transcription of ZmLEA5C could be induced by low temperature, osmotic and oxidative stress and some signaling molecules, such as abscisic acid (ABA), salicylic acid (SA) and methyl jasmonate (MeJA). However, transcription of ZmLEA5C was significantly inhibited by high salinity. Further study indicated that the ZmLEA5C protein could be phosphorylated by the protein kinase CKII. ZmLEA5C could protect the activity of LDH under water deficit and low temperature stresses. Overexpression of ZmLEA5C conferred to transgenic tobacco (Nicotiana benthamiana) and yeast (GS115) tolerance to osmotic and low temperature stresses.


      PubDate: 2014-09-05T21:59:15Z
       
  • Quantification and role of organic acids in cucumber root exudates in
           Trichoderma harzianum T-E5 colonization
    • Abstract: Publication date: October 2014
      Source:Plant Physiology and Biochemistry, Volume 83
      Author(s): Fengge Zhang , Xiaohui Meng , Xingming Yang , Wei Ran , Qirong Shen
      The ability to colonize on plant roots is recognized as one of the most important characteristics of the beneficial fungi Trichoderma spp. The aim of this study is to prove that the utilization of organic acids is a major trait of Trichoderma harzianum T-E5 for colonization of cucumber roots. A series experiments in split-root hydroponic system and in vitro were designed to demonstrate the association between the utilization of organic acids and T-E5 colonization on cucumber roots. In the split-root hydroponic system, inoculation with T-E5 (T) significantly increased the biomass of cucumber plants compared with CK (non-inoculation with T-E5). The T-E5 hyphae densely covering the cucumber root surface were observed by scanning electron microscopy (SEM). Three organic acids (oxalic acid, malic acid and citric acid) were identified from both the CK and T treatments by HPLC and LC/ESI-MS procedures. The amounts of oxalic acid and malic acid in T were significantly higher than those in CK. All the organic acids exhibited different and significant stimulation effects on the mycelial growth and conidial germination of T-E5 in vitro. An additional hydroponic experiment demonstrated the positive effects of organic acids on the T-E5 colonization of cucumber roots. In conclusion, the present study revealed that certain organic acids could be used as nutritional sources for Trichoderma harzianum T-E5 to reinforce its population on cucumber roots.


      PubDate: 2014-09-05T21:59:15Z
       
  • Cell cycle-dependent O-GlcNAc modification of tobacco histones and their
           interaction with the tobacco lectin
    • Abstract: Publication date: October 2014
      Source:Plant Physiology and Biochemistry, Volume 83
      Author(s): Annelies Delporte , Jeroen De Zaeytijd , Nico De Storme , Abdelkrim Azmi , Danny Geelen , Guy Smagghe , Yves Guisez , Els J.M. Van Damme
      The Nicotiana tabacum agglutinin or Nictaba is a nucleocytoplasmic lectin that is expressed in tobacco after the plants have been exposed to jasmonate treatment or insect herbivory. Nictaba specifically recognizes GlcNAc residues. Recently, it was shown that Nictaba is interacting in vitro with the core histone proteins from calf thymus. Assuming that plant histones – similar to their animal counterparts – undergo O-GlcNAcylation, this interaction presumably occurs through binding of the lectin to the O-GlcNAc modification present on the histones. Hereupon, the question was raised whether this modification also occurs in plants and if it is cell cycle dependent. To this end, histones were purified from tobacco BY-2 suspension cells and the presence of O-GlcNAc modifications was checked. Concomitantly, O-GlcNAcylation of histone proteins was studied. Our data show that similar to animal histones plant histones are modified by O-GlcNAc in a cell cycle-dependent fashion. In addition, the interaction between Nictaba and tobacco histones was confirmed using lectin chromatography and far Western blot analysis. Collectively these findings suggest that Nictaba can act as a modulator of gene transcription through its interaction with core histones.


      PubDate: 2014-09-01T21:31:25Z
       
  • Effective light absorption and absolute electron transport rates in the
           coral Pocillopora damicornis
    • Abstract: Publication date: October 2014
      Source:Plant Physiology and Biochemistry, Volume 83
      Author(s): Milán Szabó , Daniel Wangpraseurt , Bojan Tamburic , Anthony W.D. Larkum , Ulrich Schreiber , David J. Suggett , Michael Kühl , Peter J. Ralph
      Pulse Amplitude Modulation (PAM) fluorometry has been widely used to estimate the relative photosynthetic efficiency of corals. However, both the optical properties of intact corals as well as past technical constrains to PAM fluorometers have prevented calculations of the electron turnover rate of PSII. We used a new Multi-colour PAM (MC-PAM) in parallel with light microsensors to determine for the first time the wavelength-specific effective absorption cross-section of PSII photochemistry, σ II(λ), and thus PAM-based absolute electron transport rates of the coral photosymbiont Symbiodinium both in culture and in hospite in the coral Pocillopora damicornis. In both cases, σ II of Symbiodinium was highest in the blue spectral region and showed a progressive decrease towards red wavelengths. Absolute values for σ II at 440 nm were up to 1.5-times higher in culture than in hospite. Scalar irradiance within the living coral tissue was reduced by 20% in the blue when compared to the incident downwelling irradiance. Absolute electron transport rates of P. damicornis at 440 nm revealed a maximum PSII turnover rate of ca. 250 electrons PSII−1 s−1, consistent with one PSII turnover for every 4 photons absorbed by PSII; this likely reflects the limiting steps in electron transfer between PSII and PSI. Our results show that optical properties of the coral host strongly affect light use efficiency of Symbiodinium. Therefore, relative electron transport rates do not reflect the productivity rates (or indeed how the photosynthesis-light response is parameterised). Here we provide a non-invasive approach to estimate absolute electron transport rates in corals.


      PubDate: 2014-09-01T21:31:25Z
       
  • Molecular characterization and expression analysis of the critical floral
           genes in hickory (Carya cathayensis Sarg.)
    • Abstract: Publication date: October 2014
      Source:Plant Physiology and Biochemistry, Volume 83
      Author(s): Chen Shen , Yingwu Xu , Jianqin Huang , Zhengjia Wang , Jiani Qiu , Youjun Huang
      The full ORFs of three floral genes in hickory (Carya cathayensis Sarg.), CcAGL24 (the AGAMOUS-LIKE24 homolog), CcSOC1 (the SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 homolog) and CcAP1 (the APETALA1 homolog) are derived using a 5' RACE PCR protocol. Through sequence alignment and phylogenetic analysis, it is demonstrated that the three genes belong to the MADS-Box family. According to the evolutionary trees of the three genes, the homologous genes from the same family cluster well together, while those from different orders doesn't match evolutionary regularity of individual organisms. The result of Quantitative RT-PCR analysis shows that the transcriptional levels of the three genes are up-regulated in early stage and down-regulated in late stage in pistillate floral development. However, it takes different time to reach respective expression peak among the three genes. In staminate floral development, the transcription trend of the three genes is up-regulated, subsequently down-regulated, and then up-regulated again. Nevertheless, those trajectories, peaks, expression levels, inflection points are different in pistillate floral development. The result suggests that their functions are different in between pistillate and staminate floral development. The probable ordinal site of the three genes in the flowering network from top down is CcAGL24, CcSOC1, and CcAP1, which is identical to that in herbaceous plants. Moreover, several adverse environmental factors trigger several negative genes and then confine the development of staminate floral buds. Our results suggest the possible relationship among the three critical floral genes and their functions throughout the floral development in hickory.


      PubDate: 2014-09-01T21:31:25Z
       
  • A cotton (Gossypium hirsutum) gene encoding a NAC transcription factor is
           involved in negative regulation of plant xylem development
    • Abstract: Publication date: October 2014
      Source:Plant Physiology and Biochemistry, Volume 83
      Author(s): Wen Li , Geng-Qing Huang , Wei Zhou , Xiao-Cong Xia , Deng-Di Li , Xue-Bao Li
      NAC proteins that compose of one large family of plant specific transcription factors (TF) play the important roles in many biological processes (such as morphogenesis, development, senescence and stress signal transduction). In this study, a gene (designated as GhXND1) encoding a NAC transcription factor was identified in cotton. Sequence analysis indicated that GhXND1 gene contains two introns inserted in its open reading frame (ORF). GhXND1 protein is localized in the cell nucleus, and displays the transactivation activity. GhXND1 transcripts were mainly detected in cotyledons, petals, roots, hypocotyls and stems, but little or no signals of GhXND1 expression were found in the other tissues. Ectopic expression of GhXND1 in Arabidopsis resulted in a reduction in number of xylem vessel cells and cell wall thickness of interfascicular fibers in the transgenic plants, compared with those of wild type. And expression of some cell wall biosynthesis-related genes was down-regulated in the GhXND1 transgenic plants. Collectively, the data presented in this study suggested that GhXND1 may be involved in regulation of plant xylem development.


      PubDate: 2014-09-01T21:31:25Z
       
  • Identification of active site residues of Fenugreek β-amylase:
           Chemical modification and in silico approach
    • Abstract: Publication date: October 2014
      Source:Plant Physiology and Biochemistry, Volume 83
      Author(s): Garima Srivastava , Vinay K. Singh , Arvind M. Kayastha
      The amino acid sequence of Fenugreek β-amylase is not available in protein data bank. Therefore, an attempt has been made to identify the catalytic amino acid residues of enzyme by employing studies of pH dependence of enzyme catalysis, chemical modification and bioinformatics. Treatment of purified Fenugreek β-amylase with EDAC in presence of glycine methyl ester and sulfhydryl group specific reagents (IAA, NEM and p-CMB), followed a pseudo first-order kinetics and resulted in effective inactivation of enzyme. The reaction with EDAC in presence of NTEE (3-nitro-l-tyrosine ethylester) resulted into modification of two carboxyl groups per molecule of enzyme and presence of one accessible sulfhydryl group at the active site, per molecule of enzyme was ascertained by titration with DTNB. The above results were supported by the prevention of inactivation of enzyme in presence of substrate. Based on MALDI-TOF analysis of purified Fenugreek β-amylase and MASCOT search, β-amylase of Medicago sativa was found to be the best match. To further confirm the amino acid involved in catalysis, homology modelling of β-amylase of M. sativa was performed. The sequence alignment, superimposition of template and target models, along with study of interactions involved in docking of sucrose and maltose at the active site, led to identification of Glu187, Glu381 and Cys344 as active site residues.


      PubDate: 2014-09-01T21:31:25Z
       
  • Glutamate dehydrogenase isoenzyme 3 (GDH3) of Arabidopsis thaliana is less
           thermostable than GDH1 and GDH2 isoenzymes
    • Abstract: Publication date: October 2014
      Source:Plant Physiology and Biochemistry, Volume 83
      Author(s): Laura Marchi , Eugenia Polverini , Francesca Degola , Enrico Baruffini , Francesco Maria Restivo
      NAD(H)-glutamate dehydrogenase (GDH; EC 1.4.1.2) is an abundant and ubiquitous enzyme that may exist in different isoenzymic forms. Variation in the composition of the GDH isoenzyme pattern is observed during plant development and specific cell, tissue and organ localization of the different isoforms have been reported. However, the mechanisms involved in the regulation of the isoenzymatic pattern are still obscure. Regulation may be exerted at several levels, i.e. at the level of transcription and translation of the relevant genes, but also when the enzyme is assembled to originate the catalytically active form of the protein. In Arabidopsis thaliana, three genes (GDH1, GDH2 and GDH3) encode three different GDH subunits (β, α and γ) that randomly associate to form a complex array of homo- and hetero-hexamers. In order to asses if the different Arabidopsis GDH isoforms may display different structural properties we have investigated their thermal stability. In particular the stability of GDH1 and GDH3 isoenzymes was studied using site-directed mutagenesis in a heterologous yeast expression system. It was established that the carboxyl terminus of the GDH subunit is involved in the stabilization of the oligomeric structure of the enzyme.
      Graphical abstract image

      PubDate: 2014-09-01T21:31:25Z
       
  • Tomato susceptibility to Fusarium crown and root rot: Effect of grafting
           combination and proteomic analysis of tolerance expression in the
           rootstock
    • Abstract: Publication date: October 2014
      Source:Plant Physiology and Biochemistry, Volume 83
      Author(s): Alessandro Vitale , Mariapina Rocco , Simona Arena , Francesco Giuffrida , Carla Cassaniti , Andrea Scaloni , Tonia Lomaglio , Vladimiro Guarnaccia , Giancarlo Polizzi , Mauro Marra , Cherubino Leonardi
      Grafting can enhance the tolerance of vegetable crops to soilborne diseases. The aim of this study was to investigate whether different tomato scion–rootstock combinations may affect the plant susceptibility to Fusarium oxysporum f. sp. radicis-lycopersici (FORL), the causal agent of crown and root rot. A proteomic approach was used to investigate whenever the protein repertoire of the rootstock can be modified by FORL infection, in relation to cultivar susceptibility/tolerance to the disease. To this purpose, plants of tomato hybrids with different vigor, “Costoluto Genovese” (less vigorous) and “Kadima” (more vigorous), were grafted onto “Cuore di Bue” and “Natalia” hybrids, sensitive and tolerant versus FORL infections, respectively. Disease symptoms, plant biomasses, and protein expression patterns were evaluated 45 days after FORL inoculation. The extent of vascular discoloration caused by FORL in tomato plants grafted on “Natalia” rootstock (0.12–0.37 cm) was significantly lower than that of plants grafted on sensitive “Cuore di Bue” (1.75–6.50 cm). FORL symptoms significantly differed between “Costoluto Genovese” and “Kadima” scions only when grafted on sensitive rootstock. Shoot FW of non-inoculated “Kadima”/“Cuore di Bue” combination was 35% lower than “Kadima”/“Natalia”, whereas no difference was manifested in inoculated plants. Shoot FW of inoculated “Costoluto Genovese”/“Cuore di Bue” combination was decreased of 39%, whereas that of “Costoluto Genovese”/“Natalia” of 11%, compared to control plants. Proteomic results showed a higher representation of proteins associated with pathogen infection in the tolerant rootstock, compared to the sensitive one, meaning a direct involvement of plant defence mechanisms in the tomato response to the pathogen challenge.


      PubDate: 2014-09-01T21:31:25Z
       
  • Abscisic acid metabolite profiling as indicators of plastic responses to
           drought in grasses from arid Patagonian Monte (Argentina)
    • Abstract: Publication date: October 2014
      Source:Plant Physiology and Biochemistry, Volume 83
      Author(s): Ana M. Cenzano , O. Masciarelli , M. Virginia Luna
      The identification of hormonal and biochemical traits that play functional roles in the adaptation to drought is necessary for the conservation and planning of rangeland management. The aim of this study was to evaluate the effects of drought on i) the water content (WC) of different plant organs, ii) the endogenous level of abscisic acid (ABA) and metabolites (phaseic acid-PA, dihydrophaseic acid-DPA and abscisic acid conjugated with glucose ester-ABA-GE), iii) the total carotenoid concentration and iv) to compare the traits of two desert perennial grasses (Pappostipa speciosa and Poa ligularis) with contrasting morphological and functional drought resistance traits and life-history strategies. Both species were subjected to two levels of gravimetric soil moisture (the highest near field capacity during autumn-winter and the lowest corresponding to summer drought). Drought significantly increased the ABA and DPA levels in the green leaves of P. speciosa and P. ligularis. Drought decreased ABA in the roots of P. speciosa while it increased ABA in the roots of P. ligularis. P. ligularis had the highest ABA level and WC in green leaves. While P. speciosa had the highest DPA levels in leaves. In conclusion, we found the highest ABA level in the mesophytic species P. ligularis and the lowest ABA level in the xerophytic species P. speciosa, revealing that the ABA metabolite profile in each grass species is a plastic response to drought resistance.


      PubDate: 2014-09-01T21:31:25Z
       
  • PLASTID MOVEMENT IMPAIRED1 mediates ABA sensitivity during germination and
           implicates ABA in light-mediated Chloroplast movements
    • Abstract: Publication date: October 2014
      Source:Plant Physiology and Biochemistry, Volume 83
      Author(s): Marcela Rojas-Pierce , Craig W. Whippo , Phillip A. Davis , Roger P. Hangarter , Patricia S. Springer
      The plant hormone abscisic acid (ABA) controls many aspects of plant growth and development, including seed development, germination and responses to water-deficit stress. A complex ABA signaling network integrates environmental signals including water availability and light intensity and quality to fine-tune the response to a changing environment. To further define the regulatory pathways that control water-deficit and ABA responses, we carried out a gene-trap tagging screen for water-deficit-regulated genes in Arabidopsis thaliana. This screen identified PLASTID MOVEMENT IMPAIRED1 (PMI1), a gene involved in blue-light-induced chloroplast movement, as functioning in ABA-response pathways. We provide evidence that PMI1 is involved in the regulation of seed germination by ABA, acting upstream of the intersection between ABA and low-glucose signaling pathways. Furthermore, PMI1 participates in the regulation of ABA accumulation during periods of water deficit at the seedling stage. The combined phenotypes of pmi1 mutants in chloroplast movement and ABA responses indicate that ABA signaling may modulate chloroplast motility. This result was further supported by the detection of altered chloroplast movements in the ABA mutants aba1-6, aba2-1 and abi1-1.


      PubDate: 2014-09-01T21:31:25Z
       
  • Cyclic electron flow around photosystem I is enhanced at low pH
    • Abstract: Publication date: October 2014
      Source:Plant Physiology and Biochemistry, Volume 83
      Author(s): Teena Tongra , Sudhakar Bharti , Anjana Jajoo
      Earlier studies have shown that at low pH (pH 5.5), PS II fluorescence decreases with concomitant increase in PS I fluorescence (Singh-Rawal et al., 2010). In order to shed light on the reasons of the above stated change, spinach leaf discs were treated with buffers of different pH (7.5, 6.5 and 5.5)and decrease in the photochemical quantum yield of PS II,Y(II) and increase in the photochemical quantum yield of PS I,Y(I) was observed. We observed an enhanced protection against over-reduction of PS I acceptor side at low pH (5.5) treated leaves. This was obviously achieved by the rapid build-up of trans-thylakoid pH gradient at low light intensities and was directly associated with a steep increase in non- photochemical quenching of chlorophyll fluorescence and a decrease in the electron transport rate of PS II. Our results suggested a strong stimulation of cyclic electron flow around PS I at pH 5.5 which directly supports protection against over-reduction of the PS I acceptor side.


      PubDate: 2014-09-01T21:31:25Z
       
  • Evidences for reduced metal-uptake and membrane injury upon application of
           nitric oxide donor in cadmium stressed rice seedlings
    • Abstract: Publication date: October 2014
      Source:Plant Physiology and Biochemistry, Volume 83
      Author(s): Prerna Singh , Kavita Shah
      Heavy metal Cadmium (Cd) contaminates the environment through various anthropogenic sources. Cadmium-induced productions of free radicals lead to oxidative stress and H2O2 formation in plants. Endogenous Nitric oxide (NO) acts as signal molecules in plant stress response and play a significant role in key regulatory pathways of plant development. This study investigates the effect of 50 μM exogenous sodium nitroprusside (SNP, NO donor), on roots and shoots of rice cv. HUR 3022 grown under 50 μM Cd-stress at 7 days of growth. Plants treated with Cd alone showed stunted growth, decreased length and weight, lower cell viability and less chlorophyll. An elevated lipid peroxidation complemented with more electrolyte leakage was noted. Levels of hydrogen peroxide and superoxide anion increased in Cd-exposed plants with corresponding increase in activity of antioxidant enzymes catalase and superoxide dismutase. Lower chlorophyll levels paralleled with more uptake of cadmium in Cd-treatments as compared to controls. Application of equimolar amount of SNP to cadmium-stressed rice in the growth medium inhibited Cd-uptake and reversed the Cd-induced toxic effects by restoring membrane integrity. The levels of H2O2 and O2 − were considerably recovered due to SNP treatment. The results indicate that exogenous NO diminishes the deleterious effects of Cd in rice plants.
      Graphical abstract image

      PubDate: 2014-09-01T21:31:25Z
       
  • Multimeric states of starch phosphorylase determine protein–protein
           interactions with starch biosynthetic enzymes in amyloplasts
    • Abstract: Publication date: October 2014
      Source:Plant Physiology and Biochemistry, Volume 83
      Author(s): Renuka M. Subasinghe , Fushan Liu , Ursula C. Polack , Elizabeth A. Lee , Michael J. Emes , Ian J. Tetlow
      Protein–protein interactions between starch phosphorylase (SP) and other starch biosynthetic enzymes were investigated using isolated maize endosperm amyloplasts and a recombinant maize enzyme. Plastidial SP is a stromal enzyme existing as a multimeric protein in amyloplasts. Biochemical analysis of the recombinant maize SP indicated that the tetrameric form was catalytically active in both glucan-synthetic and phosphorolytic directions. Protein–protein interaction experiments employing the recombinant SP as an affinity ligand with amyloplast extracts showed that the multimeric state of SP determined interactions with other enzymes of the starch biosynthetic pathway. The monomeric form of SP interacts with starch branching enzyme I (SBEI) and SBEIIb, whereas only SBEI interacts with the tetrameric form of SP. In all cases, protein–protein interactions were broken when amyloplast lysates were dephosphorylated in vitro, and enhanced following pre-treatment with ATP, suggesting a mechanism of protein complex formation regulated by protein phosphorylation. In vitro protein phosphorylation experiments with [γ-32P]-ATP show that SP is phosphorylated by a plastidial protein kinase. Evidence is presented which suggests SBEIIb modulates the catalytic activity of SP through the formation of a heteromeric protein complex.


      PubDate: 2014-09-01T21:31:25Z
       
  • Overexpression of a tobacco J-domain protein enhances drought tolerance in
           transgenic Arabidopsis
    • Abstract: Publication date: October 2014
      Source:Plant Physiology and Biochemistry, Volume 83
      Author(s): Zongliang Xia , Xiaoquan Zhang , Junqi Li , Xinhong Su , Jianjun Liu
      DnaJ proteins constitute a DnaJ/Hsp40 family and are important regulators involved in diverse cellular functions. To date, the molecular mechanisms of DnaJ proteins involved in response to drought stress in plants are largely unknown. In this study, a putative DnaJ ortholog from Nicotiana tabacum (NtDnaJ1), which encodes a putative type-I J-protein, was isolated. The transcript levels of NtDnaJ1 were higher in aerial tissues and were markedly up-regulated by drought stress. Over-expression of NtDnaJ1 in Arabidopsis plants enhanced their tolerance to osmotic or drought stress. Quantitative determination of H2O2 accumulation has shown that H2O2 content increased in wild-type and transgenic seedlings under osmotic stress, but was significantly lower in both transgenic lines compared with the wild-type. Expression analysis of stress-responsive genes in NtDnaJ1-transgenic Arabidopsis revealed that there was significantly increased expression of genes involved in the ABA-dependent signaling pathway (AtRD20, AtRD22 and AtAREB2) and antioxidant genes (AtSOD1, AtSOD2, and AtCAT1). Collectively, these data demonstrate that NtDnaJ1 could be involved in drought stress response and its over-expression enhances drought tolerance possibly through regulating expression of stress-responsive genes. This study may facilitate our understandings of the biological roles of DnaJ protein-mediated abiotic stress in higher plants and accelerate genetic improvement of crop plants tolerant to environmental stresses.


      PubDate: 2014-08-15T20:21:07Z
       
  • α-Linolenic acid concentration and not wounding per se is the
           key regulator of octadecanoid (oxylipin) pathway activity in rice
           (Oryza sativa L.) leaves
    • Abstract: Publication date: October 2014
      Source:Plant Physiology and Biochemistry, Volume 83
      Author(s): John T. Christeller , Ivan Galis
      Using an in vitro system composed of crushed leaf tissues to simulate the wounding response in rice leaves, we established that synthesis of jasmonic acid (JA) and jasmonic acid-isoleucine (JA-Ile) can only occur in unwounded tissue and, in wounded tissue, that only the chloroplast-located section of the octadecanoid pathway is active, resulting in the accumulation of 12-oxo-phytodienoic acid (OPDA). We further showed that OPDA accumulation in vitro was inhibited by 90% using the general lipase inhibitor, tetrahydrolipstatin, indicating that production of α-linolenic acid was the rate-limiting step in octadecanoid pathway activity in rice following wounding and the enzyme capacity for an active pathway was already present. We confirmed this result by showing that added α-linolenic acid stimulated OPDA synthesis in vitro and stimulated OPDA, JA and JA-Ile synthesis in vivo in unwounded tissue. Thus, the response to wounding can be mimicked by the provision of free α-linolenic acid. Our results draw attention to the key importance of lipase activity in initiation of JA and JA-Ile biosynthesis and our lack of knowledge of the cognate lipase(s), lipase substrate identity and mechanism(s) of activation in wounded and unwounded tissue.
      Graphical abstract image

      PubDate: 2014-08-15T20:21:07Z
       
  • Salt stress mitigation by seed priming with UV-C in lettuce plants:
           Growth, antioxidant activity and phenolic compounds
    • Abstract: Publication date: October 2014
      Source:Plant Physiology and Biochemistry, Volume 83
      Author(s): Chayma Ouhibi , Houneida Attia , Fedia Rebah , Najoua Msilini , Mohamed Chebbi , Jawad Aarrouf , Laurent Urban , Mokhtar Lachaal
      Seeds of Lactuca sativa L. ‘Romaine’ were subjected to priming treatments with UV-C radiation at 0.85 or 3.42 kJ m−2. Seedlings obtained from both primed (Pr) and non-primed (NPr) seeds were grown in an hydroponic culture system supplemented with 0 (control) or 100 mM NaCl. After 21 days of NaCl treatment, root and leaf biomass, root lengths, leaf numbers, and leaf surface area were measured. Ions (Na+ and K+) accumulation was determined in roots and leaves. Total phenolic compound and flavonoid concentrations, as well as antioxidant and antiradical activities were measured in L. sativa leaves. Salt stress resulted in a lower increase in fresh weight of roots and leaves, which was more pronounced in roots than in leaves, due to reduced root elongation, leaf number and leaf expansion, as well as leaf thickness. The lower increase in fresh weight was accompanied by a restriction in tissue hydration and K+ ion uptake, as well as an increase in Na+ ion concentrations in all organs. These effects were mitigated in plants from the UV-C primed seeds. The mitigating effect of UV-C was more pronounced at 0.85 than at 3.42 kJ m−2. Salt stress also resulted in an increase in total phenolic compounds and flavonoid concentrations and in the total antioxidant capacity in leaves. The highest diphenylpicrylhydrazyl radical (DPPH) scavenging activity was found in the leaves of plants from both Pr seeds. Our results suggest that plants grown from seed primed by exposure to moderate UV-C radiation exhibited a higher tolerance to salinity stress.


      PubDate: 2014-08-15T20:21:07Z
       
  • Characterization of two highly similar CBF/DREB1-like genes, PhCBF4a and
           PhCBF4b, in Populus hopeiensis
    • Abstract: Publication date: October 2014
      Source:Plant Physiology and Biochemistry, Volume 83
      Author(s): Zeliang Wang , Jun Liu , Hongying Guo , Xiang He , Wanbo Wu , Jincheng Du , Zhiyi Zhang , Xinmin An
      The C-repeat binding factors (CBFs)/dehydration-responsive element-binding protein (DREBs) are a group of conserved transcription factors that play an important role in the response and adaptation to environmental stress in many plants. Two highly similar CBF/DREB1-like genes, PhCBF4a and PhCBF4b, were previously identified in Populus hopeiensis. In this paper, we describe the function of these proteins in detail in terms of abiotic stress tolerance. Phylogenic analysis suggests that PhCBF4a and PhCBF4b are expressed as two distinct alleles. Expression of both genes is induced mainly by dehydration, low-temperature, and high-salinity. Agroinfiltration experiments in tobacco leaves revealed differential transcriptional activation of the genes, likely driven by differences in their C-terminal regions. When constitutively expressed in Arabidopsis, PhCBF4a and PhCBF4b induced elevated expression of the CBF/DREB1 regulons without prior stimulus, resulting in dwarfism, delayed flowering, and greater drought tolerance compared with vector controls. These results demonstrate that PhCBF4a and PhCBF4b are functional transcriptional regulators involved in the response of P. hopeiensis to abiotic stresses.


      PubDate: 2014-08-15T20:21:07Z
       
  • Sulphate fertilization ameliorates long-term aluminum toxicity symptoms in
           perennial ryegrass (Lolium perenne)
    • Abstract: Publication date: October 2014
      Source:Plant Physiology and Biochemistry, Volume 83
      Author(s): Cristian Wulff-Zottele , Holger Hesse , Joachim Fisahn , Mariusz Bromke , Hernán Vera-Villalobos , Yan Li , Falko Frenzel , Patrick Giavalisco , Alejandra Ribera-Fonseca , Ligia Zunino , Immcolata Caruso , Evelyn Stohmann , Maria de la Luz Mora
      Effects of the oxanion sulphate on plant aluminum (Al3+) detoxification mechanisms are not well understood. Therefore, holistic physiological and biochemical modifications induced by progressively increased doses of sulphate fertilization in the presence of long-term Al3+ stress were investigated in the aluminum sensitive perennial ryegrass (Lolium perenne L. cvJumbo). Plant growth inhibition induced by Al3+ was decreased in response to increasing doses of sulphate supply. Aluminum concentrations measured in roots of perennial ryegrass by atomic absorption spectrometry declined significantly with increasing sulphate concentrations. In parallel, we determined a rise of sulphur in shoots and roots of perennial ryegrass. Inclusion of up to 360 μM of sulphate enhanced cysteine and glutathione biosynthesis in Al3+ (1.07 μM) treated plants. This increase of thiol-containing compounds favored all modifications in the glutathione redox balance, declining lipid peroxidation, decreasing the activity of superoxide dismutase, and modifying the expression of proteins involved in the diminution of Al3+ toxicity in roots. In particular, proteome analysis by 1D-SDS-PAGE and LC-MS/MS allowed to identify up (e.g. vacuolar proton ATPase, proteosome β subunit, etc) and down (Glyoxilase I, Ascorbate peroxidase, etc.) regulated proteins induced by Al3+ toxicity symptoms in roots. Although, sulphate supply up to 480 μM caused a reduction in Al3+ toxicity symptoms, it was not as efficient as compared to 360 μM sulphate fertilization. These results suggest that sulphate fertilization ameliorates Al3+ toxicity responses in an intracellular specific manner within Lolium perenne.


      PubDate: 2014-08-12T20:13:45Z
       
  • The cowpea RING ubiquitin ligase VuDRIP interacts with transcription
           factor VuDREB2A for regulating abiotic stress responses
    • Abstract: Publication date: October 2014
      Source:Plant Physiology and Biochemistry, Volume 83
      Author(s): Ayan Sadhukhan , Sanjib Kumar Panda , Lingaraj Sahoo
      Cowpea (Vigna unguiculata L. Walp) is an important grain legume cultivated in drought-prone parts of the world, having higher tolerance to heat and drought than many other crops. The transcription factor, Dehydration-Responsive Element-Binding protein 2A (DREB2A), controls expression of many genes involved in osmotic and heat stress responses of plants. In Arabidopsis, DREB2A-interacting proteins (DRIPs), which function as E3 ubiquitin ligases (EC 6.3.2.19), regulate the stability of DREB2A by targeting it for proteasome-mediated degradation. In this study, we cloned the cowpea ortholog of DRIP (VuDRIP) using PCR based methods. The 1614 bp long VuDRIP mRNA encoded a protein of 433 amino acids having a C3HC4-type Really Interesting New Gene (RING) domain in the N-terminus and a C-terminal conserved region, similar to Arabidopsis DRIP1 and DRIP2. We found VuDRIP up-regulation in response to various abiotic stresses and phytohormones. Using yeast (Saccharomyces cerevisae) two-hybrid analysis, VuDRIP was identified as a VuDREB2A-interacting protein. The results indicate negative regulation of VuDREB2A by ubiquitin ligases in cowpea similar to Arabidopsis along with their other unknown roles in stress and hormone signaling pathways.


      PubDate: 2014-08-04T19:42:17Z
       
  • Structural and functional characterization of proteinase inhibitors from
           seeds of Cajanus cajan (cv. ICP 7118)
    • Abstract: Publication date: October 2014
      Source:Plant Physiology and Biochemistry, Volume 83
      Author(s): Marri Swathi , Vadthya Lokya , Vanka Swaroop , Nalini Mallikarjuna , Monica Kannan , Aparna Dutta-Gupta , Kollipara Padmasree
      Proteinase inhibitors (C11PI) from mature dry seeds of Cajanus cajan (cv. ICP 7118) were purified by chromatography which resulted in 87-fold purification and 7.9% yield. SDS-PAGE, matrix assisted laser desorption ionization time-of-flight (MALDI-TOF/TOF) mass spectrum and two-dimensional (2-D) gel electrophoresis together resolved that C11PI possessed molecular mass of 8385.682 Da and existed as isoinhibitors. However, several of these isoinhibitors exhibited self association tendency to form small oligomers. All the isoinhibitors resolved in Native-PAGE and 2-D gel electrophoresis showed inhibitory activity against bovine pancreatic trypsin and chymotrypsin as well as Achaea janata midgut trypsin-like proteases (AjPs), a devastating pest of castor plant. Partial sequences of isoinhibitor (pI 6.0) obtained from MALDI-TOF/TOF analysis and N-terminal sequencing showed 100% homology to Bowman-Birk Inhibitors (BBIs) of leguminous plants. C11PI showed non-competitive inhibition against trypsin and chymotrypsin. A marginal loss (<15%) in C11PI activity against trypsin at 80 °C and basic pH (12.0) was associated with concurrent changes in its far-UV CD spectra. Further, in vitro assays demonstrated that C11PI possessed significant inhibitory potential (IC50 of 78 ng) against AjPs. On the other hand, in vivo leaf coating assays demonstrated that C11PI caused significant mortality rate with concomitant reduction in body weight of both larvae and pupae, prolonged the duration of transition from larva to pupa along with formation of abnormal larval-pupal and pupal-adult intermediates. Being smaller peptides, it is possible to express C11PI in castor to protect them against its devastating pest A. janata.


      PubDate: 2014-08-04T19:42:17Z
       
  • Impacts of size and shape of silver nanoparticles on Arabidopsis plant
           growth and gene expression
    • Abstract: Publication date: October 2014
      Source:Plant Physiology and Biochemistry, Volume 83
      Author(s): You-yu Syu , Jui-Hung Hung , Jui-Chang Chen , Huey-wen Chuang
      Silver nanoparticles (AgNPs) are widely used as antibacterial nanomaterials; however, the environmental impacts of AgNPs remain uncertain. In this study, Arabidopsis physiological responses and gene expression were investigated after exposure to 3 different morphologies of AgNPs. The triangular (47 ± 7 nm) and spherical (8 ± 2 nm) AgNPs exhibited the lowest and highest degrees of antimicrobial activity, respectively. The AgNP-induced phenotypic alterations in Arabidopsis were correlated with nanoparticle morphology and size, in which the decahedral AgNPs (45 ± 5 nm) induced the highest degree of root growth promotion (RGP); however, the spherical AgNPs exhibited no RGP and induced the highest levels of anthocyanin accumulation in Arabidopsis seedlings. The decahedral and spherical AgNPs induced the lowest and highest levels of Cu/Zn superoxide dismutase (CSD2) accumulation, respectively. Moreover, 3 morphologies of AgNPs induced protein accumulations including cell-division-cycle kinase 2 (CDC2), protochlorophyllide oxidoreductase (POR), and fructose-1,6 bisphosphate aldolase (FBA). Regarding transcription, the AgNPs induced the gene expression of indoleacetic acid protein 8 (IAA8), 9-cis-epoxycarotenoid dioxygenase (NCED3), and dehydration-responsive RD22. Additional studies have shown that AgNPs antagonized the aminocyclopropane-1-carboxylic acid (ACC)-derived inhibition of root elongation in Arabidopsis seedlings, as well as reduced the expression of ACC synthase 7 (ACS7) and ACC oxidase 2 (ACO2), suggesting that AgNPs acted as inhibitors of ethylene (ET) perception and could interfere with ET biosynthesis. In conclusion, AgNPs induce ROS accumulation and root growth promotion in Arabidopsis. AgNPs activate Arabidopsis gene expression involved in cellular events, including cell proliferation, metabolism, and hormone signaling pathways.


      PubDate: 2014-08-04T19:42:17Z
       
  • Molecular cloning and expression analysis of tea plant aquaporin (AQP)
           gene family
    • Abstract: Publication date: October 2014
      Source:Plant Physiology and Biochemistry, Volume 83
      Author(s): Chuan Yue , Hongli Cao , Lu Wang , Yanhua Zhou , Xinyuan Hao , Jianming Zeng , Xinchao Wang , Yajun Yang
      The role of aquaporin proteins (AQPs) has been extensively studied in plants. However, the information of AQPs in the tea plant (Camellia sinensis) is unclear. In this manuscript, we isolated 20 full-length AQP cDNAs from the tea plant, and these sequences were classified into five subfamilies. The genes in these subfamilies displayed differential expression profiles in the studied tissues. The CsAQP expression patterns correlated with flower development and opening (FDO) and bud endodormancy (BED). To better understand the short-term expression patterns of CsAQPs in response to abiotic stress, tea plants were treated with abscisic acid (ABA), cold, salt or drought. ABA treatment down-regulated the expression of various CsAQPs. Salt up-regulated the transcription of most CsAQP genes. Cold treatment resulted in a complicated transcriptional regulation pattern for various CsAQPs. The expression of CsAQPs, especially plasma membrane intrinsic proteins (CsPIPs) and tonoplast intrinsic proteins (CsTIPs), was induced by drought and remained relatively high after rehydration in leaves, whereas almost all the CsAQPs were repressed in roots. Our results highlighted the diversity of CsAQPs in the tea plant and demonstrated that the CsPIP and CsTIP genes play a vital role in the stress response as well as in FDO and BED. Furthermore, certain CsSIPs (small basic intrinsic proteins), CsNIPs (NOD26-like intrinsic proteins) and CsXIPs (X intrinsic proteins) may regulate BED and FDO.


      PubDate: 2014-08-04T19:42:17Z
       
  • Metabolomics deciphers the host resistance mechanisms in wheat cultivar
           Sumai-3, against trichothecene producing and non-producing isolates of
           Fusarium graminearum
    • Abstract: Publication date: October 2014
      Source:Plant Physiology and Biochemistry, Volume 83
      Author(s): Raghavendra Gunnaiah , Ajjamada C. Kushalappa
      Fusarium head blight (FHB) of wheat, caused by Fusarium graminearum, reduces grain yield and contaminates grains with trichothecene mycotoxins. Host resistance to FHB is quantitatively inherited and more than 100 QTLs have been mapped, but the host resistance mechanisms are poorly understood. Non-targeted metabolic profiling was applied to elucidate the host resistance mechanisms to FHB spread through rachis of wheat cultivar Sumai-3 against both trichothecene producing and non-producing isolates of Fusarium graminearum. The accumulation of deoxynivalenol (DON) in Sumai-3 was low, however the resistance to spread was not due to its detoxification into DON-3-O-glucoside (D3G), as the proportion of total DON converted to D3G in the resistant was not significantly different from that in the susceptible cultivar Roblin. Instead, the resistance was considered to be due to the accumulation of resistance related (RR) metabolites belonging to the phenylpropanoid pathway that reduced pathogen advancement through increased host cell wall thickening and also reduced pathogen growth due to antifungal and/or antioxidant properties which, in turn, reduced subsequent trichothecene biosynthesis. The RR phenylpropanoids accumulated in Sumai-3 were mainly the preformed syringyl rich monolignols and their glucosides, which are precursors of lignin biosynthesis, as well as antimicrobial flavonoids. The resistant cultivar Sumai-3 inoculated with trichothecene producing F. graminearum not only accumulated less RR metabolites but also the abundance of many RR metabolites was lesser than in the trichothecene non-producing F. graminearum. This implies repression of host resistance mechanisms by trichothecenes/DON, which is a protein biosynthesis inhibitor. Enhancement of resistance in wheat against FHB can be exploited through stacking of candidate phenylpropanoid pathway genes.


      PubDate: 2014-07-30T19:22:26Z
       
  • Differential response of Arabidopsis leaves and roots to cadmium:
           Glutathione-related chelating capacity vs antioxidant capacity
    • Abstract: Publication date: October 2014
      Source:Plant Physiology and Biochemistry, Volume 83
      Author(s): Marijke Jozefczak , Els Keunen , Henk Schat , Mattijs Bliek , Luis E. Hernández , Robert Carleer , Tony Remans , Sacha Bohler , Jaco Vangronsveld , Ann Cuypers
      This study aims to uncover the spatiotemporal involvement of glutathione (GSH) in two major mechanisms of cadmium (Cd)-induced detoxification (i.e. chelation and antioxidative defence). A kinetic study was conducted on hydroponically grown Arabidopsis thaliana (L. Heyhn) to gain insight into the early events after exposure to Cd. Cadmium detoxification was investigated at different levels, including gene transcripts, enzyme activities and metabolite content. Data indicate a time-dependent response both within roots and between plant organs. Early on in roots, GSH was preferentially allocated to phytochelatin (PC) synthesis destined for Cd chelation. This led to decreased GSH levels, without alternative pathways activated to complement GSH's antioxidative functions. After one day however, multiple antioxidative pathways increased including superoxide dismutase (SOD), ascorbate (AsA) and catalase (CAT) to ensure efficient neutralization of Cd-induced reactive oxygen species (ROS). As a consequence of Cd retention and detoxification in roots, a delayed response occurred in leaves. Together with high leaf thiol contents and possibly signalling responses from the roots, the leaves were protected, allowing them sufficient time to activate their defence mechanisms.


      PubDate: 2014-07-26T19:08:44Z
       
  • Editorial Board
    • Abstract: Publication date: September 2014
      Source:Plant Physiology and Biochemistry, Volume 82




      PubDate: 2014-07-26T19:08:44Z
       
  • Water deficit down-regulates miR398 and miR408 in pea (Pisum sativum L.)
    • Abstract: Publication date: October 2014
      Source:Plant Physiology and Biochemistry, Volume 83
      Author(s): Živko Jovanović , Nemanja Stanisavljević , Aleksandar Mikić , Svetlana Radović , Vesna Maksimović
      MicroRNAs (miRNAs), recently recognized as important regulator of gene expression at posttranscriptional level, have been found to be involved in plant stress responses. The observation that some miRNAs are up- or down regulated by stress implies that they could play vital roles in plant resistance to abiotic and biotic stress. We investigated the effect of water stress treatment during 10 days on expression of conserved miRNAs-miR398a/b and miR408 in pea plants. This time frame reflects the changes as close as possible to the changes where water stress causes visible effects under field condition. It was observed that dehydration strongly down regulates the expression of both miR398a/b and miR408 in pea roots and shoots. The down-regulation of miR398a/b and the up-regulation of potential target genes – copper superoxide dismutase, CSD1, highlight the involvement of this miRNA in pea stress response. To the contrary, the mRNA level of cytochrome c oxidase subunit 5 (COX5b) did not change in roots and shoots of water-stressed plants, compared to control (well) hydrated plants. This suggests that COX5b is not the target of miR398, or that its expression is regulated by some other mechanism. P 1B -ATPase expression increased during water deficit only in the shoots of pea; in the roots there were no changes in expression. Our results help to understand the possible role of investigated miRNAs and their contribution to pea capacity to cope with water deficit.


      PubDate: 2014-07-26T19:08:44Z
       
  • Salinity-induced accumulation of organic osmolytes in barley and wheat
           leaves correlates with increased oxidative stress tolerance:
           In planta evidence for cross-tolerance
    • Abstract: Publication date: October 2014
      Source:Plant Physiology and Biochemistry, Volume 83
      Author(s): Norhawa Puniran-Hartley , Joseph Hartley , Lana Shabala , Sergey Shabala
      Salinity tolerance in plants is dependent on their abilities to adjust osmotically to reduced soil water potential and to keep intracellular ROS levels under control. Both these processes are believed to rely on de novo synthesis of organic osmolytes (traditionally defined as compatible solutes). However direct in planta evidence for anti-oxidant roles of compatible solutes are scarce. In this work, we induced changes in the level of endogenous organic osmolytes by exposing plants to various levels of NaCl (salinity stress; 50–300 mM range) and then studying sensitivity of leaves to oxidative (UV–B) stress. Increase in the external NaCl concentrations was accompanied by the progressive accumulation in leaf Na+. This accumulation was much higher in old leaves compared with young ones. In old leaves, three major inorganic ions (Na+, Cl− and K+) have made 67.7% and 70.4% of leaf osmotic potential (in wheat and barley, respectively) when exposed to 200 mM NaCl treatment, while in young leaves their contribution was only 43.9% and 46.8%, respectively. Here, organic osmolytes played a substantial role in leaf osmotic adjustment. Increased accumulation of organic osmolytes correlated strongly with activity of PSII in leaves exposed to oxidation inducing UV-B treatment in both species (R 2 = 0.50 for wheat and 0.71 for barley). We conclude that salinity-induced accumulation of organic osmolytes in barley and wheat leaves correlates with increased oxidative stress tolerance and provides the evidence for a mechanism of cross-tolerance between these two stresses.


      PubDate: 2014-07-26T19:08:44Z
       
  • A stress responsive gene of Fortunella crassifolia FcSISP functions in
           salt stress resistance
    • Abstract: Publication date: October 2014
      Source:Plant Physiology and Biochemistry, Volume 83
      Author(s): Xiaoqing Gong , Jingyan Zhang , Ji-Hong Liu
      Exploration of genes functioning in salt tolerance is crucial for generating transgenic plants with enhanced salt tolerance. In this study, we report the isolation and functional characterization of a stress-responsive gene FcSISP from Meiwa kumquat (Fortunella crassifolia). FcSISP encodes a putative protein of 47 amino acids, with a calculated molecular mass of 4.94 kDa and theoretical isoelectric point of 3.76, and was localized in the nucleus. Transcript levels of FcSISP were induced by dehydration, cold, salt and bacterium causing citrus canker, and hormones (salicylic acid and abscisic acid), with the greatest induction under salt treatment. Overexpression of FcSISP in tobacco (Nicotiana nudicaulis) conferred enhanced salt tolerance. The transgenic lines accumulated lower Na+ contents, leading to reduced Na/K ratio, but accumulated more proline than the wild type (WT). Steady state mRNA levels of genes involved in Na+ exchange (three SOS genes and three NHX genes) and proline synthesis (P5CS and P5CR) were higher in the transgenic lines in comparison with WT. Moreover, overexpression of FcSISP in trifoliate orange [Poncirus trifoliata (L.) Raf.], a widely-used and salt-sensitive citrus rootstock, led to elevated salt tolerance. Taken together, the data demonstrate that FcSISP plays a positive role in salt tolerance and that it holds a great potential for engineering salt tolerance in crops.


      PubDate: 2014-07-26T19:08:44Z
       
  • Selection and validation of reference genes for transcript normalization
           in gene expression studies in Catharanthus roseus
    • Abstract: Publication date: October 2014
      Source:Plant Physiology and Biochemistry, Volume 83
      Author(s): Jacob Pollier , Robin Vanden Bossche , Heiko Rischer , Alain Goossens
      Quantitative Real-Time PCR (qPCR), a sensitive and commonly used technique for gene expression analysis, requires stably expressed reference genes for normalization of gene expression. Up to now, only one reference gene for qPCR analysis, corresponding to 40S Ribosomal protein S9 (RPS9), was available for the medicinal plant Catharanthus roseus, the only source of the commercial anticancer drugs vinblastine and vincristine. Here, we screened for additional reference genes for this plant species by mining C. roseus RNA-Seq data for orthologs of 22 genes known to be stably expressed in Arabidopsis thaliana and qualified as superior reference genes for this model plant species. Based on this, eight candidate C. roseus reference genes were identified and, together with RPS9, evaluated by performing qPCR on a series of different C. roseus explants and tissue cultures. NormFinder, geNorm and BestKeeper analyses of the resulting qPCR data revealed that the orthologs of At2g28390 (SAND family protein, SAND), At2g32170 (N2227-like family protein, N2227) and At4g26410 (Expressed protein, EXP) had the highest expression stability across the different C. roseus samples and are superior as reference genes as compared to the traditionally used RPS9. Analysis of publicly available C. roseus RNA-Seq data confirmed the expression stability of SAND and N2227, underscoring their value as reference genes for C. roseus qPCR analysis.


      PubDate: 2014-07-26T19:08:44Z
       
 
 
JournalTOCs
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
Email: journaltocs@hw.ac.uk
Tel: +00 44 (0)131 4513762
Fax: +00 44 (0)131 4513327
 
About JournalTOCs
API
Help
News (blog, publications)
JournalTOCs on Twitter   JournalTOCs on Facebook

JournalTOCs © 2009-2014