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Journal Cover   Plant Physiology and Biochemistry
  [SJR: 1.041]   [H-I: 70]   [9 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0981-9428
   Published by Elsevier Homepage  [2811 journals]
  • Characterisation of plants expressing the human
           β1,4-galactosyltrasferase gene
    • Abstract: Publication date: Available online 13 April 2015
      Source:Plant Physiology and Biochemistry
      Author(s): Jeannine Schneider , Alexandra Castilho , Martin Pabst , Friedrich Altmann , Clemens Gruber , Richard Strasser , Pia Gattinger , Georg Seifert , Herta Steinkellner
      Modification of the plant N-glycosylation pathway towards human type structures is an important strategy to implement plants as expression systems for therapeutic proteins. Nevertheless, relatively little is known about the overall impact of non-plant glycosylation enzymes in stable transformed plants. Here, we analyzed transgenic lines (Nicotiana benthamiana and Arabidopsis thaliana) that stably express a modified version of human β1,4-galactosyltransferase (STGalT). While some transgenic plants grew normally, other lines exhibited a severe phenotype associated with stunted growth and developmental retardation. The severity of the phenotype correlated with both increased STGalT mRNA and protein levels but no differences were observed between N-glycosylation profiles of plants with and without the phenotype. In contrast to non-transgenic plants, all STGalT expressing plants synthesized significant amounts of incompletely processed (largely depleted of core fucose) N-glycans with up to 40 % terminally galactosylated structures. While transgenic plants showed no differences in nucleotide sugar composition and cell wall monosaccharide content, alterations in the reactivity of cell wall carbohydrate epitopes associated with arabinogalactan-proteins and pectic homogalacturonan were detected in STGalT expressing plants. Notably, plants with phenotypic alterations showed increased levels of hydrogen peroxide, most probably a consequence of hypersensitive reactions. Our data demonstrate that unfavourable phenotypical modifications may occur upon stable in planta expression of non-native glycosyltransferases. Such important issues need to be taken into consideration in respect to stable glycan engineering in plants.

      PubDate: 2015-04-17T05:16:52Z
  • Sulfate supply influences compartment specific glutathione metabolism and
           confers enhanced resistance to Tobacco mosaic virus during a
           hypersensitive response
    • Abstract: Publication date: October 2012
      Source:Plant Physiology and Biochemistry, Volume 59
      Author(s): Lóránt Király , András Künstler , Kerstin Höller , Maria Fattinger , Csilla Juhász , Maria Müller , Gábor Gullner , Bernd Zechmann
      Sufficient sulfate supply has been linked to the development of sulfur induced resistance or sulfur enhanced defense (SIR/SED) in plants. In this study we investigated the effects of sulfate (S) supply on the response of genetically resistant tobacco (Nicotiana tabacum cv. Samsun NN) to Tobacco mosaic virus (TMV). Plants grown with sufficient sulfate (+S plants) developed significantly less necrotic lesions during a hypersensitive response (HR) when compared to plants grown without sulfate (−S plants). In +S plants reduced TMV accumulation was evident on the level of viral RNA. Enhanced virus resistance correlated with elevated levels of cysteine and glutathione and early induction of a Tau class glutathione S-transferase and a salicylic acid-binding catalase gene. These data indicate that the elevated antioxidant capacity of +S plants was able to reduce the effects of HR, leading to enhanced virus resistance. Expression of pathogenesis-related genes was also markedly up-regulated in +S plants after TMV-inoculation. On the subcellular level, comparison of TMV-inoculated +S and −S plants revealed that +S plants contained 55–132 % higher glutathione levels in mitochondria, chloroplasts, nuclei, peroxisomes and the cytosol than −S plants. Interestingly, mitochondria were the only organelles where TMV-inoculation resulted in a decrease of glutathione levels when compared to mock-inoculated plants. This was particularly obvious in −S plants, where the development of necrotic lesions was more pronounced. In summary, the overall higher antioxidative capacity and elevated activation of defense genes in +S plants indicate that sufficient sulfate supply enhances a preexisting plant defense reaction resulting in reduced symptom development and virus accumulation.
      Highlights ► Sulfate as possible enhancer of plant defense during virus infection. ► Sulfate fertilization reduces symptom severity and virus contents. ► Enhanced cysteine and glutathione metabolism up-regulates defense gene expression. ► Sulfate fertilization enhances plant defense during virus infection.

      PubDate: 2015-04-13T05:00:37Z
  • Cell wall composition of tomato fruit changes during development and
           inhibition of vesicle trafficking is associated with reduced pectin levels
           and reduced softening
    • Abstract: Publication date: May 2013
      Source:Plant Physiology and Biochemistry, Volume 66
      Author(s): Daniel Lunn , Thanh D. Phan , Gregory A. Tucker , Grantley W. Lycett
      Fruit development entails a multitude of biochemical changes leading up to the mature green stage. During this period the cell wall will undergo complex compositional and structural changes. Inhibition of genes encoding elements of the machinery involved in trafficking to the cell wall presents us with a useful tool to study these changes and their associated phenotypes. An antisense SlRab11a transgene has previously been shown to reduce ripening-associated fruit softening. SlRab11a is highly expressed during fruit development which is associated with a period of pectin influx into the wall. We have analysed the cell wall polysaccharides at different stages of growth and ripening of wild type and antisense SlRab11a transgenic tomato (Solanum lycopersicum cv, Ailsa Craig) fruit. Our results demonstrated intriguing changes in cell wall composition during the development and ripening of wild type Alisa Craig tomato fruit. Analysis of SlRab11a expression by TaqMan PCR showed it to be expressed most strongly during growth of the fruit, suggesting a possible role in cell wall deposition. The SlRab11a antisense fruit had a decreased proportion of pectin in the cell wall compared with the wild type. We suggest a new approach for modification of fruit shelf-life by changing cell wall deposition rather than cell wall hydrolytic enzymes.
      Highlights ► The pectin content of wild type tomato fruit went up during fruit development. ► Pectin esterification has been estimated at stages prior to breaker. ► SlRab11a was expressed most strongly during fruit expansion. ► SlRab11a antisense transformed fruit accumulate less pectin than wild type. ► We suggest a new approach to address fruit spoilage.

      PubDate: 2015-04-13T05:00:37Z
  • Temporary reduction of radiation does not permanently reduce flavonoid
           glycosides and phenolic acids in red lettuce
    • Abstract: Publication date: November 2013
      Source:Plant Physiology and Biochemistry, Volume 72
      Author(s): Christine Becker , Hans-Peter Kläring , Lothar W. Kroh , Angelika Krumbein
      Applying transparent daytime screens in greenhouses in cool seasons reduces the amount of energy needed for heating, but also the solar radiation available for crops. This can reduce yield and product quality of leafy vegetables because of constrained photosynthesis and altered biosynthesis. To study this, we cultivated five-week old red leaf lettuce (Lactuca sativa L.) for four weeks in growth chambers under a photosynthetic photon flux density (PPFD) of 225 and 410 μmol m−2 s−1, respectively. Some plants were exchanged between radiation intensities after two weeks. We investigated the concentration of five flavonoid glycosides, three caffeic acid derivatives, reducing sugars as well as plant growth. Remarkably, no significant influence of radiation intensity on the concentration of phenolic acids or anthocyanin glycosides was observed. In contrast, quercetin and luteolin glycoside concentration was between 14 and 34% lower in plants growing under lower compared to higher PPFD. Already after two weeks of cultivation, plants grown under lower PPFD contained less quercetin and luteolin glycosides but they completely compensated if subsequently transferred to higher PPFD until harvest. Hence, marketable lettuce heads which experienced temporary shading followed by an unshaded phase did not contain lower concentrations of flavonoid glycosides or phenolic acids. Also, there was no reduction of head mass in this variant. Our results suggest that saving energy in early growth stages is feasible without losses in yield or health promoting phenolic substances. In addition, there was a close correlation between the concentration of reducing sugars and some flavonoid glycosides, indicating a close metabolic connection between their biosynthesis and the availability of carbohydrates.

      PubDate: 2015-04-13T05:00:37Z
  • The AAP gene family for amino acid permeases contributes
           to development of the cyst nematode Heterodera schachtii in roots of
    • Abstract: Publication date: September 2013
      Source:Plant Physiology and Biochemistry, Volume 70
      Author(s): Abdelnaser Elashry , Sakiko Okumoto , Shahid Siddique , Wolfgang Koch , David P. Kreil , Holger Bohlmann
      The beet cyst nematode Heterodera schachtii is able to infect Arabidopsis plants and induce feeding sites in the root. These syncytia are the only source of nutrients for the nematodes throughout their life and are a nutrient sink for the host plant. We have studied here the role of amino acid transporters for nematode development. Arabidopsis contains a large number of different amino acid transporters in several gene families but those of the AAP family were found to be especially expressed in syncytia. Arabidopsis contains 8 AAP genes and they were all strongly expressed in syncytia with the exception of AAP5 and AAP7, which were slightly downregulated. We used promoter::GUS lines and in situ RT-PCR to confirm the expression of several AAP genes and LHT1, a lysine- and histidine-specific amino acid transporter, in syncytia. The strong expression of AAP genes in syncytia indicated that these transporters are important for the transport of amino acids into syncytia and we used T-DNA mutants for several AAP genes to test for their influence on nematode development. We found that mutants of AAP1, AAP2, and AAP8 significantly reduced the number of female nematodes developing on these plants. Our study showed that amino acid transport into syncytia is important for the development of the nematodes.

      PubDate: 2015-04-13T05:00:37Z
  • Structural and functional differences of cytosolic 90-kDa heat-shock
           proteins (Hsp90s) in Arabidopsis thaliana
    • Abstract: Publication date: September 2013
      Source:Plant Physiology and Biochemistry, Volume 70
      Author(s): Joon-Yung Cha , Gyeongik Ahn , Joo Yeon Kim , Sun Bin Kang , Mi Ri Kim , Mukhamad Su'udi , Woe-Yeon Kim , Daeyoung Son
      The seven members of the 90-kDa heat shock protein (Hsp90) family encode highly conserved molecular chaperones essential for cell survival in Arabidopsis thaliana. Hsp90 are abundant proteins, localized in different compartments with AtHsp90.1-4 in the cytosol and AtHsp90.5-7 in different organelles. Among the AtHsp90, AtHsp90.1, is stress-inducible and shares comparatively low sequence identity with the constitutively expressed AtHsp90.2-4. Even though abundant information is available on mammalian cytosolic Hsp90 proteins, it is unknown whether cytosolic Hsp90 proteins display different structural and functional properties. We have now analyzed two A. thalianas cytosolic Hsp90s, AtHsp90.1 and AtHsp90.3, for functional divergence. AtHsp90.3 showed higher holdase chaperone activity than AtHsp90.1, although both AtHsp90s exhibited effective chaperone activity. Size-exclusion chromatography revealed different oligomeric states distinguishing the two Hsp90 proteins. While AtHsp90.1 exists in several oligomeric states, including monomers, dimers and higher oligomers, AtHsp90.3 exists predominantly in a high oligomeric state. High oligomeric state of AtHsp90.1 showed higher holdase chaperone activity than the respective monomer or dimer states. When high oligomeric forms of AtHsp90.1 and AtHsp90.3 are reduced by DTT, activity was reduced compared to that found in the native high oligomeric state. In addition, ATP-dependent foldase chaperone activity of AtHsp90.3 was higher with strong intrinsic ATPase activity than that of AtHsp90.1. As a conclusion, the two A. thaliana cytosolic Hsp90 proteins display different functional activities depending on structural differences, implying functional divergence although the proteins are localized to the same sub-cellular organelle.

      PubDate: 2015-04-13T05:00:37Z
  • Single-nucleotide polymorphisms and association analysis of
           drought-resistance gene TaSnRK2.8 in common wheat
    • Abstract: Publication date: September 2013
      Source:Plant Physiology and Biochemistry, Volume 70
      Author(s): Hongying Zhang , Xinguo Mao , Jianan Zhang , Xiaoping Chang , Ruilian Jing
      TaSnRK2.8, an SnRK2 (sucrose non-fermenting1-related protein kinase 2) member of wheat, confers enhanced multi-stress tolerances in carbohydrate metabolism. In the study, two types of genomic sequences of TaSnRK2.8 were detected in common wheat. Sequencing analysis showed that there was a variation-enriched region, designated TaSnRK2.8-A-C, covering the eighth intron, the ninth exon and the 3′-flanking region of TaSnRK2.8-A, and no divergence occurred in TaSnRK2.8-B. Single nucleotide polymorphisms in the TaSnRK2.8-A-C region were investigated in 165 wheat accessions. Three of 751 sequenced nucleotide sites were polymorphic. Nucleotide diversity (π) in the region was 0.00068. Sliding-window analysis demonstrated that the nucleotide diversity was highest in the 3′-flanking sequence. As predicted, the highly frequent SNP was significantly associated with seedling biomass under normal conditions, plant height, flag leaf width and water-soluble carbohydrate content under drought conditions. Analysis of variance of correlated traits between accessions with the A and G genotypes indicated that the A variant was the more favorable allele associated with significantly increased seedling biomass and water-soluble carbohydrates. Based on the SNP, we developed a functional marker of TaSnRK2.8-A-C, that could be utilized in wheat breeding programs aimed at improving seedling biomass and water-soluble carbohydrates, and consequently to enhance stress resistance in wheat.

      PubDate: 2015-04-13T05:00:37Z
  • The volatile metabolome of grapevine roots: First insights into the
           metabolic response upon phylloxera attack
    • Abstract: Publication date: September 2011
      Source:Plant Physiology and Biochemistry, Volume 49, Issue 9
      Author(s): Nora C. Lawo , Georg J.F. Weingart , Rainer Schuhmacher , Astrid Forneck
      Many plant species respond to herbivore attack by an increased formation of volatile organic compounds. In this preliminary study we analysed the volatile metabolome of grapevine roots [Teleki 5C (Vitis berlandieri Planch. × Vitis riparia Michx.)] with the aim to gain insight into the interaction between phylloxera (Daktulosphaira vitifoliae Fitch; Hemiptera: Phylloxeridae) and grapevine roots. In the first part of the study, headspace solid phase microextraction (HS-SPME) coupled to gas chromatography – mass spectrometry (GC–MS) was used to detect and identify volatile metabolites in uninfested and phylloxera-infested root tips of the grapevine rootstock Teleki 5C. Based on the comparison of deconvoluted mass spectra with spectra databases as well as experimentally derived retention indices with literature values, 38 metabolites were identified, which belong to the major classes of plant volatiles including C6-compounds, terpenes (including modified terpenes), aromatic compounds, alcohols and n-alkanes. Based on these identified metabolites, changes in root volatiles were investigated and resulted in metabolite profiles caused by phylloxera infestation. Our preliminary data indicate that defence related pathways such as the mevalonate and/or alternative isopentenyl pyrophosphate-, the lipoxygenase- (LOX) as well as the phenylpropanoid pathway are affected in root galls as a response to phylloxera attack.
      Highlights ► 38 volatiles identified in healthy and phylloxera-infested grapevine root samples by GC–MS. ► Fourteen differentially expressed metabolites in phylloxera-infested grapevine root tips. ► Root infestation by phylloxera is associated with defence response in grapevine. ► MEV/alt. IPP-, phenylpropanoid- and LOX pathways are affected upon phylloxera attack.

      PubDate: 2015-04-13T05:00:37Z
  • The promoter of a plant defensin gene directs specific expression in
           nematode-induced syncytia in Arabidopsis roots
    • Abstract: Publication date: October 2011
      Source:Plant Physiology and Biochemistry, Volume 49, Issue 10
      Author(s): Shahid Siddique , Krzysztof Wieczorek , Dagmar Szakasits , David P. Kreil , Holger Bohlmann
      The beet cyst nematode Heterodera schachtii induces a feeding site, called syncytium, in roots of host plants. In Arabidopsis, one of the genes whose expression is strongly induced in these structures is Pdf2.1 which codes for an antimicrobial plant defensin. Arabidopsis has 13 plant defensin genes. Besides Pdf2.1, the Pdf2.2 and Pdf2.3 genes were strongly expressed in syncytia and therefore the expression of all three Pdf genes was studied in detail. The promoter of the Pdf2.1 gene turned out to be an interesting candidate to drive a syncytium-specific expression of foreign genes as RT-PCR showed that apart from the feeding site it was only expressed in siliques (seeds). The Pdf2.2 and Pdf2.3 genes were in addition expressed in seedlings, roots, leaves, stems, and flowers. These results were supported by the analysis of promoter::GUS lines. After infection with H. schachtii all GUS lines showed a strong staining in syncytia at 5 and 15 dpi. This expression pattern was confirmed by in situ RT-PCR.
      Highlights ► 3 plant defensin genes are strongly expressed in syncytia. ► Pdf2.1 is expressed in syncytia and seeds. ► The Pdf2.1 promoter is useful for the expression of foreign genes in syncytia.

      PubDate: 2015-04-13T05:00:37Z
  • Varied response of Spodoptera littoralis against Arabidopsis thaliana with
           metabolically engineered glucosinolate profiles
    • Abstract: Publication date: January 2012
      Source:Plant Physiology and Biochemistry, Volume 50
      Author(s): Sarosh Bejai , Ingela Fridborg , Barbara Ekbom
      Upon herbivory glucosinolates are known to be degraded into a cascade of secondary products that can be detrimental for certain herbivores. We performed herbivory bioassays using first and second instar generalist Lepidoptera larvae Spodoptera littoralis on Arabidopsis thaliana engineered to overexpress novel glucosinolates. A differential response in larval feeding patterns was observed on the plants engineered with novel glucosinolates. Larvae fed on plants overexpressing 4-hydroxybenzyl glucosinolate and isopropyl glucosinolate showed little response. Larvae fed on 35S:CYP79A2 plants engineered to overexpress benzyl glucosinolates, however, showed reduced larval and pupal weights. Upon herbivory a high expression of JA signalling gene LOX2 was observed on the 35S:CYP79A2 plants compared to the PR1a and VSP2 expression. To confirm the role of benzyl isothiocyanate (BITC), a degradation product of benzyl glucosinolate overexpressing plants, in the retarded larval growth we used Virus Induced Gene Silencing (VIGS) approach to silence LOX2 expression in the 35S:CYP79A2 plants. S. littoralis larvae fed on LOX2 silenced 35S:CYP79A2 plants exhibited a retarded larval growth thus indicating that BITC played a pivotal role in anti-herbivory and not only the JA signalling pathway.
      Highlights ► A differential response in Spodoptera littoralis larval feeding patterns was observed on the plants engineered with novel glucosinolates. ► Larvae fed on 35S:CYP79A2 plant engineered to overexpress benzyl glucosinolate showed reduced larval and pupal weights. ► Benzyl isothiocyanate (BITC), a degradation product of benzylglucosinolate may be a potential inhibitor for insect herbivory. ► Virus Induced Gene Silencing (VIGS) was used to silence LOX2 in 35S:CYP79A2 lines to confirm anti-herbivore defense.

      PubDate: 2015-04-13T05:00:37Z
  • Tc-cAPX, a cytosolic ascorbate peroxidase of Theobroma cacao
           L. engaged in the interaction with Moniliophthora perniciosa,
           the causing agent of witches' broom disease
    • Abstract: Publication date: December 2013
      Source:Plant Physiology and Biochemistry, Volume 73
      Author(s): Luciana Rodrigues Camillo , Ciro Ribeiro Filadelfo , Paulo Sérgio Monzani , Ronan Xavier Corrêa , Karina Peres Gramacho , Fabienne Micheli , Carlos Priminho Pirovani
      The level of hydrogen peroxide (H2O2) in plants signalizes the induction of several genes, including that of ascorbate peroxidase (APX-EC APX isoenzymes play a central role in the elimination of intracellular H2O2 and contribute to plant responses to diverse stresses. During the infection process in Theobroma cacao by Moniliophthora perniciosa oxidative stress is generated and the APX action recruited from the plant. The present work aimed to characterize the T. cacao APX involved in the molecular interaction of T. cacao–M. perniciosa. The peroxidase activity was analyzed in protein extracts from cocoa plants infected by M. perniciosa and showed the induction of peroxidases like APX in resistant cocoa plants. The cytosolic protein of T. cacao (GenBank: ABR68691.2) was phylogenetically analyzed in relation to other peroxidases from the cocoa genome and eight genes encoding APX proteins with conserved domains were also analyzed. The cDNA from cytosolic APX was cloned in pET28a and the recombinant protein expressed and purified (rTc-cAPX). The secondary structure of the protein was analyzed by Circular Dichroism (CD) displaying high proportion of α-helices when folded. The enzymatic assay shows stable activity using ascorbate and guaiacol as an electron donor for H2O2 reduction. The pH 7.5 is the optimum for enzyme activity. Chromatographic analysis suggests that rTc-cAPX is a homodimer in solution. Results indicate that the rTc-cAPX is correctly folded, stable and biochemically active. The purified rTc-cAPX presented biotechnological potential and is adequate for future structural and functional studies.

      PubDate: 2015-04-13T05:00:37Z
  • UV-B induction of the E3 ligase ARIADNE12 depends on CONSTITUTIVELY
    • Abstract: Publication date: Available online 23 March 2015
      Source:Plant Physiology and Biochemistry
      Author(s): Lisi Xie , Christina Lang-Mladek , Julia Richter , Neha Nigam , Marie-Theres Hauser
      The UV-B inducible ARIADNE12 (ARI12) gene of Arabidopsis thaliana is a member of the RING-between-RING (RBR) family of E3 ubiquitin ligases for which a novel ubiquitination mechanism was identified in mammalian homologs. This RING-HECT hybrid mechanism needs a conserved cysteine which is replaced by serine in ARI12 and might affect the E3 ubiquitin ligase activity. We have shown that under photomorphogenic UV-B, ARI12 is a downstream target of the classical ultraviolet B (UV-B) UV RESISTANCE LOCUS 8 (UVR8) pathway. However, under high fluence rate of UV-B ARI12 was induced independently of UVR8 and the UV-A/blue light and red/far-red photoreceptors. A key component of several light signaling pathways is CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1). Upon UV-B COP1 is trapped in the nucleus through interaction with UVR8 permitting the activation of genes that regulate the biosynthesis of UV-B protective metabolites and growth adaptations. To clarify the role of COP1 in the regulation of ARI12 mRNA expression and ARI12 protein stability, localization and interaction with COP1 was assessed with and without UV-B. We found that COP1 controls ARI12 in white light, low and high fluence rate of UV-B. Furthermore we show that ARI12 is indeed an E3 ubiquitin ligase which is mono-ubiquitinated, a prerequisite for the RING-HECT hybrid mechanism. Finally, genetic analyses with transgenes expressing a genomic pmARI12:ARI12-GFP construct confirm the epistatic interaction between COP1 and ARI12 in growth responses to high fluence rate UV-B.

      PubDate: 2015-04-03T17:51:32Z
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