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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  [2570 journals]   [SJR: 0.996]   [H-I: 63]
  • Overexpression of codA gene confers enhanced tolerance to abiotic stresses
           in alfalfa
    • Abstract: Publication date: Available online 18 October 2014
      Source:Plant Physiology and Biochemistry
      Author(s): Hongbing Li , Zhi Wang , Qingbo Ke , Chang Yoon Ji , Jae Cheol Jeong , Haeng-Soon Lee , Yong Pyo Lim , Bingcheng Xu , Xi-Ping Deng , Sang-Soo Kwak
      We generated transgenic alfalfa plants (Medicago sativa L. cv. Xinjiang Daye) expressing a bacterial codA gene in chloroplasts under the control of the SWPA2 promoter (referred to as SC plants) and evaluated the plants under various abiotic stress conditions. Three transgenic plants (SC7, SC8, and SC9) were selected for further characterization based on the strong expression levels of codA in response to methyl viologen (MV)-mediated oxidative stress. SC plants showed enhanced tolerance to NaCl and drought stress on the whole plant level due to induced expression of codA. When plants were subjected to 250 mM NaCl treatment for 2 weeks, SC7 and SC8 plants maintained higher chlorophyll contents and lower malondialdehyde levels than non-transgenic (NT) plants. Under drought stress conditions, all SC plants showed enhanced tolerance to drought stress through maintaining high relative water contents and increased levels of glycinebetaine and proline compared to NT plants. Under normal conditions, SC plants exhibited increased growth due to increased expression of auxin-related IAA genes compared to NT plants. These results suggest that the SC plants generated in this study will be useful for enhanced biomass production on global marginal lands, such as high salinity and arid lands, yielding a sustainable agricultural product.


      PubDate: 2014-10-22T03:34:47Z
       
  • Streptomyces rhizobacteria modulate the secondary metabolism of Eucalyptus
           plants
    • Abstract: Publication date: December 2014
      Source:Plant Physiology and Biochemistry, Volume 85
      Author(s): Tamiris Daros Salla , Thanise Ramos da Silva , Leandro Vieira Astarita , Eliane Romanato Santarém
      The genus Eucalyptus comprises economically important species, such as Eucalyptus grandis and Eucalyptus globulus, used especially as a raw material in many industrial sectors. Species of Eucalyptus are very susceptible to pathogens, mainly fungi, which leads to mortality of plant cuttings in rooting phase. One alternative to promote plant health and development is the potential use of microorganisms that act as agents for biological control, such as plant growth-promoting rhizobacteria (PGPR). Rhizobacteria Streptomyces spp have been considered as PGPR. This study aimed at selecting strains of Streptomyces with ability to promote plant growth and modulate secondary metabolism of E. grandis and E. globulus in vitro plants. The experiments assessed the development of plants (root number and length), changes in key enzymes in plant defense (polyphenol oxidase and peroxidase) and induction of secondary compounds (total phenolic and quercetinic flavonoid fraction). The isolate Streptomyces PM9 showed highest production of indol-3-acetic acid and the best potential for root induction. Treatment of Eucalyptus roots with Streptomyces PM9 caused alterations in enzymes activities during the period of co-cultivation (1–15 days), as well as in the levels of phenolic compounds and flavonoids. Shoots also showed alteration in the secondary metabolism, suggesting induced systemic response. The ability of Streptomyces sp. PM9 on promoting root growth, through production of IAA, and possible role on modulation of secondary metabolism of Eucalyptus plants characterizes this isolate as PGPR and indicates its potential use as a biological control in forestry.


      PubDate: 2014-10-17T03:23:23Z
       
  • Salts and nutrients present in regenerated waters induce changes in water
           relations, antioxidative metabolism, ion accumulation and restricted ion
           uptake in Myrtus communis L. plants
    • Abstract: Publication date: Available online 16 October 2014
      Source:Plant Physiology and Biochemistry
      Author(s): José R. Acosta-Motos , Sara Álvarez , Gregorio Barba-Espín , José A. Hernández , María J. Sanchez-Blanco
      The use of reclaimed water (RW) constitutes a valuable strategy for the efficient management of water and nutrients in landscaping. However, RW may contain levels of toxic ions, affecting plant production or quality, a very important aspect for ornamental plants. The present paper evaluates the effect of different quality RWs on physiological and biochemical parameters and the recovery capacity in Myrtus communis L. plants. M. communis plants were submitted to 3 irrigation treatments with RW from different sources (22 weeks): RW1 (1.7 dS m−1), RW2 (4.0 dS m−1) and RW3 (8.0 dS m−1) and one control (C, 0.8 dS m−1). During a recovery period of 11 weeks, all plants were irrigated with the control water. The RW treatments did not negatively affect plant growth, while RW2 even led to an increase in biomass. After recovery, only plants irrigated with RW3 showed some negative effects on growth, which was related to a decrease in the net photosynthesis rate, higher Na accumulation and a reduction in K levels. An increase in salinity was accompanied by decreases in leaf water potential, relative water content and gas exchange parameters, and increases in Na and Cl uptake. Plants accumulated Na in roots and restricted its translocation to the aerial part. The highest salinity levels produced oxidative stress, as seen from the rise in electrolyte leakage and lipid peroxidation. The use of regenerated water together with carefully managed drainage practices, which avoid the accumulation of salt by the substrate, will provide economic and environmental benefits.


      PubDate: 2014-10-17T03:23:23Z
       
  • Cerium oxide nanoparticles alter the antioxidant capacity but do not
           impact tuber ionome in Raphanus sativus (L)
    • Abstract: Publication date: November 2014
      Source:Plant Physiology and Biochemistry, Volume 84
      Author(s): Baltazar Corral-Diaz , Jose R. Peralta-Videa , Emilio Alvarez-Parrilla , Joaquin Rodrigo-García , Maria Isabel Morales , Pedro Osuna-Avila , Genhua Niu , Jose A. Hernandez-Viezcas , Jorge L. Gardea-Torresdey
      The effects of nCeO2 on food quality are not well known yet. This research was performed to determine the impact of nCeO2 on radish (Raphanus sativus L.). Plants were cultivated to full maturity in potting soil treated with nCeO2 at concentrations of 0, 62.5, 125, 250, and 500 mg/kg. Germination, growth, photosynthesis, ionome, and antioxidants were evaluated at different growth stages. Results showed that at 500 mg/kg, nCeO2 significantly retarded seed germination but did not reduce the number of germinated seeds. None of the treatments affected gas exchange, photosynthesis, growth, phenols, flavonoids, and nutrients' accumulation in tubers and leaves of adult plants. However, tubers' antioxidant capacity, expressed as FRAP, ABTS•− and DPPH, increased by 30%, 32%, and 85%, respectively, in plants treated with 250 mg nCeO2 kg−1 soil. In addition, cerium accumulation in tubers of plants treated with 250 and 500 mg/kg reached 72 and 142 mg/kg d wt, respectively. This suggests that nCeO2 could improve the radical scavenging potency of radish but it might introduce nCeO2 into the food chain with unknown consequences.


      PubDate: 2014-10-17T03:23:23Z
       
  • Gibberellin secreting rhizobacterium, Pseudomonas putida H-2-3 modulates
           the hormonal and stress physiology of soybean to improve the plant growth
           under saline and drought conditions
    • Abstract: Publication date: November 2014
      Source:Plant Physiology and Biochemistry, Volume 84
      Author(s): Sang-Mo Kang , Ramalingam Radhakrishnan , Abdul Latif Khan , Min-Ji Kim , Jae-Man Park , Bo-Ra Kim , Dong-Hyun Shin , In-Jung Lee
      The physiological changes in tolerant soybean plants under salt and drought stress conditions with Pseudomonas putida H-2-3 were investigated. A bacterial isolate H-2-3 was isolated from soil and identified as Pseudomonas putida H-2-3 by 16S rDNA sequences. The treatment of P. putida H-2-3 significantly increased the length, fresh and dry weight of shoot and chlorophyll content in gibberellins (GAs) deficient mutant Waito-c rice seedlings over the control, it might be the presence of GA1, GA4, GA9 and GA20. The soybean plant growth was retarded in salt (120 mM sodium chloride) and drought (15% polyethylene glycol) stress conditions at 10 days treatments, while P. putida H-2-3 effectively enhanced the shoot length and fresh weight of plants suffered at salt and drought stress. The chlorophyll content was lower in abiotic stress conditions and bacterial inoculant P. putida H-2-3 mitigated the stress effects by an evidence of higher quantity of chlorophyll content in plants exposed to salt and drought. The stress hormonal analysis revealed that individual treatment of P. putida H-2-3, salt and drought significantly enhanced the abscisic acid and salicylic acid content than their control. P. putida H-2-3 applied to salt and drought stressed plants showed a lower level of abscisic acid and salicylic acid and a higher level of jasmonic acid content. Under stress condition induced by salt and drought in plants expressed higher level of total polyphenol, superoxide dismutase and radical scavenging activity and no significant changes in flavonoids. The bio-inoculant, P. putida H-2-3 modulated those antioxidants by declining superoxide dismutase, flavonoids and radical scavenging activity. P. putida H-2-3 induced tolerance against abiotic stress was confirmed by a reduction of Na content in abiotic stressed plants. The results suggest that P. putida H-2-3 application reprograms the chlorophyll, stress hormones and antioxidants expression in abiotic stress affected soybean plant and improves their growth under stress environment.


      PubDate: 2014-10-12T03:06:44Z
       
  • Endogenous hormones response to cytokinins with regard to organogenesis in
           explants of peach (Prunus persica L. Batsch) cultivars and rootstocks (P.
           persica × Prunus dulcis)
    • Abstract: Publication date: November 2014
      Source:Plant Physiology and Biochemistry, Volume 84
      Author(s): Margarita Pérez-Jiménez , Elena Cantero-Navarro , Francisco Pérez-Alfocea , José Cos-Terrer
      Organogenesis in peach (Prunus persica L. Batsch) and peach rootstocks (P. persica × Prunus dulcis) has been achieved and the action of the regeneration medium on 7 phytohormones, zeatin (Z), zeatin riboside (ZR), indole-3-acetic acid (IAA), abscisic acid (ABA), ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC), salicylic acid (SA), and jasmonic acid (JA), has been studied using High performance liquid chromatography – mass spectrometry (HPLC-MS/MS). Three scion peach cultivars, ‘UFO-3’, ‘Flariba’ and ‘Alice Bigi’, and the peach × almond rootstocks ‘Garnem’ and ‘GF677’ were cultured in two different media, Murashige and Skoog supplemented with plant growth regulators (PGRs) (regeneration medium) and without PGRs (control medium), in order to study the effects of the media and/or genotypes in the endogenous hormones content and their role in organogenesis. The highest regeneration rate was obtained with the peach × almond rootstocks and showed a lower content of Z, IAA, ABA, ACC and JA. Only Z, ZR and IAA were affected by the action of the culture media. This study shows which hormones are external PGRs-dependent and what is the weight of the genotype and hormones in peach organogenesis that provide an avenue to manipulate in vitro organogenesis in peach.


      PubDate: 2014-10-12T03:06:44Z
       
  • Role of Fe-responsive genes in bioreduction and transport of ionic gold to
           roots of Arabidopsis thaliana during synthesis of gold nanoparticles
    • Abstract: Publication date: November 2014
      Source:Plant Physiology and Biochemistry, Volume 84
      Author(s): Ajay Jain , Bhaskaran Sinilal , Daniel L. Starnes , Raghavendrarao Sanagala , Sneha Krishnamurthy , Shivendra V. Sahi
      Several studies have shown potassium chloroaurate (KAuCl4)-mediated synthesis of gold nanoparticles (AuNPs) by using extracts of different parts of diverse plant species. However, the mechanism underlying the formation of AuNPs in planta has far from being elucidated. Here, we report the molecular evidence towards the role of genes involved in iron (Fe) homeostasis during in planta synthesis of AuNPs in roots of Arabidopsis thaliana. Firstly, we examined the dosage-dependent effects of KAuCl4 treatment on primary root length (PRL), and meristematic activity of roots in transgenic CycB1;1::uidA. Compared to control seedling (0 ppm KAuCl4), PRL and meristematic activity of primary and lateral roots showed progressive attenuation in seedlings treated with higher concentrations of KAuCl4 (25 ppm or above). Therefore, subsequent studies on in planta synthesis of AuNPs, and molecular responses were carried out in roots of the seedlings treated with 10 ppm KAuCl4 for 7 d. TEM of KAuCl4-treated seedlings showed the presence of monodisperse AuNPs of different shapes and sizes in root biomatrix. There was a significant induction of FRO2 in KAuCl4-treated roots, and therefore its likely involvement in bioreduction of Au3 + could be assumed. Elevated expression levels of Fe transporters IRT1 and IRT2 further suggested their potential role in transport of bioreduced Au3+ across root membrane. Expression levels of other genes involved in Fe homeostasis, and also different members of zinc (Zn), phosphate (Pi), and potassium (K) transporter families remained unaffected by KAuCl4 treatment. An increased Au content in Fe-deprived roots further provided evidence towards the specific role of a subset of Fe-responsive genes during in planta synthesis of AuNPs.


      PubDate: 2014-10-12T03:06:44Z
       
  • Insight into small RNA abundance and expression in high- and
           low-temperature stress response using deep sequencing in Arabidopsis
    • Abstract: Publication date: November 2014
      Source:Plant Physiology and Biochemistry, Volume 84
      Author(s): Vesselin Baev , Ivan Milev , Mladen Naydenov , Tihomir Vachev , Elena Apostolova , Nikolay Mehterov , Mariyana Gozmanva , Georgi Minkov , Gaurav Sablok , Galina Yahubyan
      Small RNA profiling and assessing its dependence on changing environmental factors have expanded our understanding of the transcriptional and post-transcriptional regulation of plant stress responses. Insufficient data have been documented earlier to depict the profiling of small RNA classes in temperature-associated stress which has a wide implication for climate change biology. In the present study, we report a comparative assessment of the genome-wide profiling of small RNAs in Arabidopsis thaliana using two conditional responses, induced by high- and low-temperature. Genome-wide profiling of small RNAs revealed an abundance of 21 nt small RNAs at low temperature, while high temperature showed an abundance of 21 nt and 24 nt small RNAs. The two temperature treatments altered the expression of a specific subset of mature miRNAs and displayed differential expression of a number of miRNA isoforms (isomiRs). Comparative analysis demonstrated that a large number of protein-coding genes can give rise to differentially expressed small RNAs following temperature shifts. Low temperature caused accumulation of small RNAs, corresponding to the sense strand of a number of cold-responsive genes. In contrast, high temperature stimulated the production of small RNAs of both polarities from genes encoding functionally diverse proteins.


      PubDate: 2014-10-12T03:06:44Z
       
  • Apples: Content of phenolic compounds vs. variety, part of apple and
           cultivation model, extraction of phenolic compounds, biological properties
           
    • Abstract: Publication date: November 2014
      Source:Plant Physiology and Biochemistry, Volume 84
      Author(s): Monika Kalinowska , Aleksandra Bielawska , Hanna Lewandowska-Siwkiewicz , Waldemar Priebe , Włodzimierz Lewandowski
      Apples are among the most popular fruits in the world. They are rich in phenolic compounds, pectin, sugar, macro- and microelements. Applying different extraction techniques it is possible to isolate a particular group of compounds or individual chemicals and then test their biological properties. Many reports point to the antioxidant, antimicrobial, anticancer and many other beneficial effects of apple components that may have potential applications in food, pharmaceutical and cosmetic industries. This paper summarizes and compiles information about apple phenolic compounds, their biological properties with particular emphasis on health-related aspects. The data are reviewed with regard to different apple varieties, part of apple, cultivation model and methods of extraction.
      Graphical abstract image

      PubDate: 2014-10-12T03:06:44Z
       
  • Comparison of distinct transcriptional expression patterns of flavonoid
           biosynthesis in Cabernet Sauvignon grapes from east and west China
    • Abstract: Publication date: November 2014
      Source:Plant Physiology and Biochemistry, Volume 84
      Author(s): Qiang Li , Fei He , Bao-Qing Zhu , Bin Liu , Run-Ze Sun , Chang-Qing Duan , Malcolm J. Reeves , Jun Wang
      Flavonoids make a very important contribution to the organoleptic qualities of grapes and wines. In this work these were analyzed in Cabernet Sauvignon grown in Changli, Hebei Province in east China and Gaotai, Gansu Province in west China. These regions have distinctly different climates contributing to their different ‘terroir’. RNA sequencing was performed to trace transcriptome changes in Cabernet Sauvignon berries at pea size, veraison and ripening, corresponding to E-L 31, 35 and 38. The accumulation of flavonols, flavan-3-ols and anthocyanins together with the expression of relevant genes were analyzed and compared between the two regions. The biosynthesis patterns were similar between two regions, but more flavonols, anthocyanins, and tri-hydroxylated flavonoids accumulated in grapes from Gaotai before berry harvest, possibly due to the higher transcript levels of the genes that encode biosynthetic enzymes and their potential candidate transcription factors. The lower levels of flavan-3-ols, mainly (−)-epigallocatechin, in the pre-veraison grapes from Changli, might be due to limited flow of carbon to the F3′5′H branch pathway, as the ratio of F3′5′H to F3′H was lower in these berries from Changli. It is suggested that the combination of climatic factors profoundly affect the flavonoid pathway in grapes from China, providing regionally specific metabolism patterns.
      Graphical abstract image

      PubDate: 2014-10-12T03:06:44Z
       
  • Response to drought and salt stress in leaves of poplar (Populus
           alba × Populus glandulosa): Expression profiling by
           oligonucleotide microarray analysis
    • Abstract: Publication date: November 2014
      Source:Plant Physiology and Biochemistry, Volume 84
      Author(s): Seo-Kyung Yoon , Eung-Jun Park , Young-Im Choi , Eun-Kyung Bae , Joon-Hyeok Kim , So-Young Park , Kyu-Suk Kang , Hyoshin Lee
      Drought and salt stresses are major environmental constraints on forest productivity. To identify genes responsible for stress tolerance, we conducted a genome-wide analysis in poplar (Populus alba × Populus glandulosa) leaves exposed to drought and salt (NaCl) stresses. We investigated gene expression at the mRNA level using oligonucleotide microarrays containing 44,718 genes from Populus trichocarpa. A total of 1604 and 1042 genes were up-regulated (≥2-fold; P value < 0.05) by drought and salt stresses, respectively, and 765 genes were up-regulated by both stresses. In addition, 2742 and 1685 genes were down-regulated by drought and salt stresses, respectively, and 1564 genes were down-regulated by both stresses. The large number of genes regulated by both stresses suggests that crosstalk occurs between the drought and salt stress responses. Most up-regulated genes were involved in functions such as subcellular localization, signal transduction, metabolism, and transcription. Among the up-regulated genes, we identified 47 signaling proteins, 65 transcription factors, and 43 abiotic stress-related genes. Several genes were modulated by only one of the two stresses. About 25% of the genes significantly regulated by these stresses are of unknown function, suggesting that poplar may provide an opportunity to discover novel stress-related genes.


      PubDate: 2014-10-12T03:06:44Z
       
  • Editorial Board
    • Abstract: Publication date: October 2014
      Source:Plant Physiology and Biochemistry, Volume 83




      PubDate: 2014-10-12T03:06:44Z
       
  • Enzymatic conversion from pyridoxal to pyridoxine caused by microorganisms
           within tobacco phyllosphere
    • Abstract: Publication date: Available online 11 October 2014
      Source:Plant Physiology and Biochemistry
      Author(s): ShuoHao Huang , JianYun Zhang , Zhen Tao , Liang Lei , YongHui Yu , LongQuan Huang
      Vitamin B6 (VB6) comprises six interconvertible pyridine compounds (vitamers), among which pyridoxal 5′-phosphate (PLP) is a coenzyme involved in a high diversity of biochemical reactions. In plants, PLP is de novo synthesized, and pyridoxine (PN) is usually maintained as the predominant B6 vitamer. Although the conversion from pyridoxal (PL) to PN catalyzed by PL reductase in plants has been confirmed, the enzyme itself remains largely unknown. We previously found pre-incubation at 35 °C dramatically enhanced PL reductase activity in tobacco leaf homogenate. In this study, we demonstrated that the increase in the reductase activity was a consequence of phyllosphere microbial proliferation. VB6 was detected from tobacco phyllosphere, and PL level was the highest among three non-phosphorylated B6 vitamers. When the sterile tobacco rich in PL were kept in an open, warm and humid environment to promote microorganism proliferation, a significant change from PL to PN was observed. Our results suggest that there may be a plant–microbe interaction in the conversion from PL to PN within tobacco phyllosphere.


      PubDate: 2014-10-12T03:06:44Z
       
  • Localization of tobacco germin-like protein 1 in leaf intercellular space
    • Abstract: Publication date: Available online 7 October 2014
      Source:Plant Physiology and Biochemistry
      Author(s): Mitsuko Kishi-Kaboshi , Hirona Muto , Atsushi Takeda , Takashi Murata , Mitsuyasu Hasebe , Yuichiro Watanabe
      To characterize leaf cell wall proteins relating the architectural changes of leaves, we analyzed Nicotiana tabacum leaf cell wall proteins that were extracted by the treatment with lithium chloride. Some of these proteins showed amino acid sequence homology to some germin-like proteins (GLP). Based of those sequences, we isolated the cDNA encoding the GLPs (NtGLP1-1, NtGLP2-1). Phylogenetic analysis including de novo assembled tobacco GLPs using EST clones, revealed that tobacco GLPs belong to at least 5 different subgroups of GLP and both NtGLP1 and NtGLP2 belong to GLP subfamily 3. We showed that the NtGLP1 actually localizes to cell wall and revealed that it predominantly localized at specific sites on the leaf cell wall where intercellular attachment was just bifurcated. Expression of the NtGLP1 mRNA was mainly detected in leaves especially at elongating stage. NtGLP1 is possibly relevant to development of leaf intercellular space.
      Graphical abstract image

      PubDate: 2014-10-12T03:06:44Z
       
  • Cultivar variability of iron uptake mechanisms in rice (Oryza sativa L.)
    • Abstract: Publication date: Available online 11 October 2014
      Source:Plant Physiology and Biochemistry
      Author(s): Margarida P. Pereira , Carla Santos , Ana Gomes , Marta W. Vasconcelos
      Rice (Oryza sativa L.) is the most important staple food in the world. It is rich in genetic diversity and can grow in a wide range of environments. Iron (Fe) deficiency is a major abiotic stress in crop production and in aerobic soils, where Fe forms insoluble complexes, and is not readily available for uptake. To cope with Fe deficiency, plants developed mechanisms for Fe uptake, and although rice was described as a Strategy II plant, recent evidence suggests that it is capable of utilizing mechanisms from both Strategies. The main objective of this work was to compare two cultivars, Bico Branco (japonica) and Nipponbare (tropical japonica), to understand if the regulation of Fe uptake mechanisms could be cultivar (cv.) dependent. Plants of both cultivars were grown under Fe-deficient and -sufficient conditions and physiological and molecular responses to Fe deficiency were evaluated. Bico Branco cv. developed more leaf chlorosis and was more susceptible to Fe deficiency, retaining more nutrients in roots, than Nipponbare cv., which translocated more nutrients to shoots. Nipponbare cv. presented higher levels of Fe reductase activity, which was significantly up-regulated by Fe deficiency, and had higher expression levels of the Strategy I-OsFRO2 gene in roots, while Bico Branco cv. induced more genes involved in Strategy II. These new findings show that rice cultivars have different responses to Fe deficiency and that the induction of Strategy I or II may be rice cultivar-dependent, although the utilization of the reduction mechanisms seems to be an ubiquitous advantage.


      PubDate: 2014-10-12T03:06:44Z
       
  • Diadenosine triphosphate is a novel factor which in combination with
           cyclodextrins synergistically enhances the biosynthesis of
           trans-resveratrol in Vitis vinifera cv. Monastrell suspension cultured
           cells
    • Abstract: Publication date: November 2014
      Source:Plant Physiology and Biochemistry, Volume 84
      Author(s): Małgorzata Pietrowska-Borek , Łukasz Czekała , Sarai Belchí-Navarro , María Angeles Pedreño , Andrzej Guranowski
      Dinucleoside polyphosphates are considered as signal molecules that may evoke response of plant cells to stress. Other compounds whose biological effects have been recognized are cyclodextrins. They are cyclic oligosaccharides that chemically resemble the alkyl-derived pectic oligosaccharides naturally released from the cell walls during fungal attack, and they act as true elicitors, since, when added to plant cell culture, they induce the expression of genes involved in some secondary metabolism pathways. Previously, we demonstrated that some dinucleoside polyphosphates triggered the biosynthesis of enzymes involved in the phenylpropanoid pathway in Arabidopsis thaliana. In Vitis vinifera suspension cultured cells, cyclodextrins were shown to enhance the accumulation of trans-resveratrol, one of the basic units of the stilbenes derived from the phenylpropanoid pathway. Here, we show that diadenosine triphosphate, applied alone or in combination with cyclodextrins to the grapevine suspension-cultured cells, increased the transcript level of genes encoding key phenylpropanoid-pathway enzymes as well as the trans-resveratrol production inside cells and its secretion into the extracellular medium. In the latter case, these two compounds acted synergistically. However, the accumulation of trans-resveratrol and its glucoside trans-piceid inside cells were stimulated much better by diadenosine triphosphate than by cyclodextrins.


      PubDate: 2014-10-12T03:06:44Z
       
  • Occurrence of a number of enzymes involved in either gluconeogenesis or
           other processes in the pericarp of three cultivars of grape (Vitis
           vinifera L.) during development
    • Abstract: Publication date: November 2014
      Source:Plant Physiology and Biochemistry, Volume 84
      Author(s): Franco Famiani , Stefano Moscatello , Nicoletta Ferradini , Tiziano Gardi , Alberto Battistelli , Robert P. Walker
      It is uncertain whether the enzymes pyruvate orthophosphate dikinase (PPDK) or isocitrate lyase (ICL) are present in the pericarp of grape, in which they could function in gluconeogenesis. The occurrence of these and other enzymes was investigated in the pericarp of three cultivars of grape (Vitis vinifera L.). In particular, the abundance of the enzymes aldolase, glutamine synthase (GS), acid invertase, ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), phosphoenolpyruvate carboxylase (PEPC), PPDK and ICL were determined during the development of the pericarp of the cultivars Cabernet Sauvignon, Chardonnay and Zibibbo. PPDK and ICL were not detected at any stage of development. Each of the other enzymes showed different changes in abundance during development. However, for a given enzyme its changes in abundance were similar in each cultivar. In the ripe pericarp of Cabernet Sauvignon, PEPC, cytosolic GS and aldolase were equally distributed between the vasculature and parenchyma cells of the flesh and skin. The absence or very low abundance of PPDK provides strong evidence that any gluconeogenesis from malate utilises phosphoenolpyruvate carboxykinase (PEPCK). The absence or very low abundance of ICL in the pericarp precludes any gluconeogenesis from ethanol.


      PubDate: 2014-10-12T03:06:44Z
       
  • TaSK5, an abiotic stress-inducible GSK3/shaggy-like kinase from wheat,
           confers salt and drought tolerance in transgenic Arabidopsis
    • Abstract: Publication date: November 2014
      Source:Plant Physiology and Biochemistry, Volume 84
      Author(s): Nikolai Kirilov Christov , Petya Koeva Christova , Hideki Kato , Yuelin Liu , Kentaro Sasaki , Ryozo Imai
      A novel cold-inducible GSK3/shaggy-like kinase, TaSK5, was isolated from winter wheat using a macroarray-based differential screening approach. TaSK5 showed high similarity to Arabidopsis subgroup I GSK3/shaggy-like kinases ASK-alpha, AtSK-gamma and ASK-epsilon. RNA gel blot analyses revealed TaSK5 induction by cold and NaCl treatments and to a lesser extent by drought treatment. TaSK5 functionally complemented the cold- and salt-sensitive phenotypes of a yeast GSK3/shaggy-like kinase mutant, △mck1. Transgenic Arabidopsis plants overexpressing TaSK5 cDNA showed enhanced tolerance to salt and drought stresses. By contrast, the tolerance of the transgenic plants to freezing stress was not altered. Microarray analysis revealed that a number of abiotic stress-inducible genes were constitutively induced in the transgenic Arabidopsis plants, suggesting that TaSK5 may function in a novel signal transduction pathway that appears to be unrelated to DREB1/CBF regulon and may involve crosstalk between abiotic and hormonal signals.


      PubDate: 2014-10-12T03:06:44Z
       
  • Modifications of the chemical structure of phenolics differentially affect
           physiological activities in pulvinar cells of Mimosa pudica L. I.
           Multimode effect on early membrane events
    • Abstract: Publication date: November 2014
      Source:Plant Physiology and Biochemistry, Volume 84
      Author(s): Françoise Rocher , Fabienne Dédaldéchamp , Saed Saeedi , Pierrette Fleurat-Lessard , Jean-Francois Chollet , Gabriel Roblin
      A study of the structure–activity relationship carried out on several benzoic acid-related phenolics indicates that this type of compounds hinders the osmocontractile reaction of pulvinar cells in the range of 0–100%. Tentatively, we tried to find a way that could explain this differential action. With this aim, the relationship between the inhibitory effect and important molecular physico-chemical parameters (namely lipophilicity and degree of dissociation) was drawn. In addition, the effect of a variety of these compounds was investigated on their capacity to modify the electrical transmembrane potential and induce modifications in proton fluxes. Finally, using plasma membrane vesicles purified from pulvinar tissues, we examined the effects of some selected compounds on the proton pump activity and catalytic activity of the plasma membrane H+-ATPase. Taken together, the results indicate that a modification of the molecular structure of phenolics may induce important variation in the activity of the compound on these early membrane events. Among the tested phenolics, salicylic acid (SA) and acetylsalicylic acid (ASA, aspirin) are of particuler note, as they showed atypical effects on the physiological processes studied.


      PubDate: 2014-10-12T03:06:44Z
       
  • Acceleration of cyclic electron flow in rice plants (Oryza sativa L.)
           deficient in the PsbS protein of Photosystem II
    • Abstract: Publication date: November 2014
      Source:Plant Physiology and Biochemistry, Volume 84
      Author(s): Ismayil S. Zulfugarov , Altanzaya Tovuu , Choon-Hwan Lee
      When compared with Photosystem I (PSI) in wild-type (WT) rice plants, PSI in PsbS-knockout (KO) plants that lack the energy-dependent component of nonphotochemical quenching (NPQ) was less sensitive to photoinhibition. Therefore, we investigated the relationship between NPQ and cyclic electron flow (CEF) around PSI as a photoprotective mechanism. Activities of two CEF routes (PGR5-dependent or NDH-dependent) were compared between those genotypes by using both dark-adapted plants and pre-illuminated plants, i.e., those in which the Calvin–Benson cycle is de-activated and activated, respectively. In dark-adapted leaves activity of the PGR5-dependent route was determined as the rate of P700 photooxidation. Activity was higher in the mutants than in the WT. However, no difference was noted when plants of either genotype were pre-illuminated. When the electron transport pathway was switched to the cyclic mode by infiltrating leaf segments with 150 mM sorbitol, 40 μM DCMU, and 2 mM hydroxylamine, the rate of P700 oxidation was faster in the mutant. That difference disappeared when leaves were infiltrated with antimycin A to inhibit the PGR5-dependent route. Chlorophyll fluorescence (Fo) was also evaluated. To achieve an Fo level comparable to that of the WT, activation of the NDH-dependent route in the mutant required pre-illumination at a certain dose. Therefore, we propose that, as an alternate pathway for the photoprotection of photosystems in the absence of energy-dependent quenching, this PGR5-dependent route is more highly activated in the PsbS-KO mutants than in the WT. Moreover, that stronger activity is probably responsible for slower activation of the NDH-dependent route in the mutant.


      PubDate: 2014-10-12T03:06:44Z
       
  • Speciation and localization of Zn in the hyperaccumulator Sedum alfredii
           by extended X-ray absorption fine structure and micro-X-ray fluorescence
    • Abstract: Publication date: November 2014
      Source:Plant Physiology and Biochemistry, Volume 84
      Author(s): Lingli Lu , Xingcheng Liao , John Labavitch , Xiaoe Yang , Erik Nelson , Yonghua Du , Patrick H. Brown , Shengke Tian
      Differences in metal homeostasis among related plant species can give important information of metal hyperaccumulation mechanisms. Speciation and distribution of Zn were investigated in a hyperaccumulating population of Sedum alfredii by using extended X-ray absorption fine structure and micro-synchrotron X-ray fluorescence (μ-XRF), respectively. The hyperaccumulator uses complexation with oxygen donor ligands for Zn storage in leaves and stems, and variations in the Zn speciation was noted in different tissues. The dominant chemical form of Zn in leaves was most probably a complex with malate, the most prevalent organic acid in S. alfredii leaves. In stems, Zn was mainly associated with malate and cell walls, while Zn–citrate and Zn–cell wall complexes dominated in the roots. Two-dimensional μ-XRF images revealed age-dependent differences in Zn localization in S. alfredii stems and leaves. In old leaves of S. alfredii, Zn was high in the midrib, margin regions and the petiole, whereas distribution of Zn was essentially uniform in young leaves. Zinc was preferentially sequestered by cells near vascular bundles in young stems, but was highly localized to vascular bundles and the outer cortex layer of old stems. The results suggest that tissue- and age-dependent variations of Zn speciation and distribution occurred in the hyperaccumulator S. alfredii, with most of the Zn complexed with malate in the leaves, but a shift to cell wall– and citric acid–Zn complexes during transportation and storage in stems and roots. This implies that biotransformation in Zn complexation occurred during transportation and storage processes in the plants of S. alfredii.


      PubDate: 2014-10-12T03:06:44Z
       
  • Low temperature storage affects the ascorbic acid metabolism of cherry
           tomato fruits
    • Abstract: Publication date: November 2014
      Source:Plant Physiology and Biochemistry, Volume 84
      Author(s): Georgios Tsaniklidis , Costas Delis , Nikolaos Nikoloudakis , Panagiotis Katinakis , Georgios Aivalakis
      Tomato fruits are an important source of l-Ascorbic acid, which is an essential compound of human diet. The effect of the widespread practice of cold storing (5–10 °C) tomato fruits was monitored to determine its impact on the concentration and redox status of l-Ascorbic acid. Total l-Ascorbic acid levels were well maintained in both attached fruits and cold treated fruits, while in other treatments its levels were considerably reduced. However, low temperature storage conditions enhanced the expression of most genes coding for enzymes involved in l-Ascorbic acid biosynthesis and redox reactions. The findings suggest that the transcriptional up-regulation under chilling stress conditions of most genes coding for l-Ascorbic acid biosynthetic genes galactono-1,4-lactone dehydrogenase, GDP-d-mannose 3,5-epimerase but also for the isoenzymes of ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase enzyme, glutathione reductase that are strongly correlated to the l-Ascorbic redox status. Moreover, fruits stored at 10 °C exhibited higher levels of transcript accumulation of MDHAR2, DHAR1, DHAR2, GR1 and GR2 genes, pointing to a better ability to manage chilling stress in comparison to fruits stored at 5 °C.


      PubDate: 2014-10-12T03:06:44Z
       
  • Molecular characterization of edestin gene family in Cannabis sativa L.
    • Abstract: Publication date: November 2014
      Source:Plant Physiology and Biochemistry, Volume 84
      Author(s): Teresa Docimo , Immacolata Caruso , Elena Ponzoni , Monica Mattana , Incoronata Galasso
      Globulins are the predominant class of seed storage proteins in a wide variety of plants. In many plant species globulins are present in several isoforms encoded by gene families. The major seed storage protein of Cannabis sativa L. is the globulin edestin, widely known for its nutritional potential. In this work, we report the isolation of seven cDNAs encoding for edestin from the C. sativa variety Carmagnola. Southern blot hybridization is in agreement with the number of identified edestin genes. All seven sequences showed the characteristic globulin features, but they result to be divergent members/forms of two edestin types. According to their sequence similarity four forms named CsEde1A, CsEde1B, CsEde1C, CsEde1D have been assigned to the edestin type 1 and the three forms CsEde2A, CsEde2B, CsEde2C to the edestin type 2. Analysis of the coding sequences revealed a high percentage of similarity (98–99%) among the different forms belonging to the same type, which decreased significantly to approximately 64% between the forms belonging to different types. Quantitative RT-PCR analysis revealed that both edestin types are expressed in developing hemp seeds and the amount of CsEde1 was 4.44 ± 0.10 higher than CsEde2. Both edestin types exhibited a high percentage of arginine (11–12%), but CsEde2 resulted particularly rich in methionine residues (2.36%) respect to CsEde1 (0.82%). The amino acid composition determined in CsEde1 and CsEde2 types suggests that these seed proteins can be used to improve the nutritional quality of plant food-stuffs.


      PubDate: 2014-10-12T03:06:44Z
       
  • Flower color patterning in pansy (Viola × wittrockiana
           Gams.) is caused by the differential expression of three genes from the
           anthocyanin pathway in acyanic and cyanic flower areas
    • Abstract: Publication date: November 2014
      Source:Plant Physiology and Biochemistry, Volume 84
      Author(s): Qin Li , Jian Wang , Hai-Yan Sun , Xiao Shang
      The petals of pansy (Viola × wittrockiana Gams.) ‘Mengdie’ exhibit a cyanic blotched pigmentation pattern. The accumulation of anthocyanins, cyanidin and delphinidin, was detected in the upper epidermal cells of the cyanic blotches. In order to elucidate the mechanism by which cyanic blotches are formed in pansy petal, the expression level of genes involved in anthocyanin synthesis was measured and compared between cyanic blotches and acyanic areas of the flower. The use of primers in conserved regions allowed the successful isolation of six cDNA clones encoding putative anthocyanin enzymes from pansy petals. The clones isolated encoded chalcone synthase (CHS), chalcone isomerase (CHI), flavanone 3-hydroxylase (F3H), flavonoid 3′-hydroxylase (F3′H), dihydroflavonol 4-reductase (DFR) and anthocyanidin synthase (ANS). The transcription patterns of seven genes (VwCHS, VwCHI, VwF3H, VwF3′H, VwDFR, VwF3′5′H, and VwANS) in cyanic blotches and acyanic areas of the petals at seven stages of flower development were determined by real-time quantitative PCR. Transcription of VwF3′5′H, VwDFR and VwANS was significantly increased in cyanic blotches at stages III–V of flower development, implicating these genes in the pigmentation of Viola × wittrockiana Gams. petals.
      Graphical abstract image

      PubDate: 2014-10-12T03:06:44Z
       
  • The role of the F-box gene TaFBA1 from wheat (Triticum aestivum L.) in
           drought tolerance
    • Abstract: Publication date: November 2014
      Source:Plant Physiology and Biochemistry, Volume 84
      Author(s): Shumei Zhou , Xiudong Sun , Suhong Yin , Xiangzhu Kong , Shan Zhou , Ying Xu , Yin Luo , Wei Wang
      Drought is one of the most important factors limiting plant growth and development. We identified a gene in wheat (Triticum aestivum L.) under drought stress named TaFBA1. TaFBA1 encodes a putative 325-amino-acid F-box protein with a conserved N-terminal F-box domain and a C-terminal AMN1 domain. Real-time RT-PCR analysis revealed that TaFBA1 transcript accumulation was upregulated by high-salinity, water stress, and abscisic acid (ABA) treatment. To evaluate the functions of TaFBA1 in the regulation of drought stress responses, we produced transgenic tobacco lines overexpressing TaFBA1. Under water stress conditions, the transgenic tobacco plants had a higher germination rate, higher relative water content, net photosynthesis rate (Pn), less chlorophyll loss, and less growth inhibition than WT. These results demonstrate the high tolerance of the transgenic plants to drought stress compared to the WT. The enhanced oxidative stress tolerance of these plants, which may be involved in their drought tolerance, was indicated by their lower levels of reactive oxygen species (ROS) accumulation, MDA content, and cell membrane damage under drought stress compared to WT. The antioxidant enzyme activities were higher in the transgenic plants than in WT, which may be related to the upregulated expression of some antioxidant genes via overexpression of TaFBA1.


      PubDate: 2014-10-12T03:06:44Z
       
  • Involvement of ethylene-responsive microRNAs and their targets in
           increased latex yield in the rubber tree in response to ethylene treatment
           
    • Abstract: Publication date: November 2014
      Source:Plant Physiology and Biochemistry, Volume 84
      Author(s): Porawee Pramoolkit , Manassawe Lertpanyasampatha , Unchera Viboonjun , Panida Kongsawadworakul , Hervé Chrestin , Jarunya Narangajavana
      The rubber tree is an economically important plant that produces natural rubber for various industrial uses. The application of ethylene contributes to increased latex production in rubber trees; however, the molecular biology behind the effects of ethylene on latex yield remains to be elucidated. Recently, the intersection between microRNA (miRNA) regulation and phytohormone responses has been revealed. Insight into the regulation of miRNAs and their target genes should help to determine the functional importance of miRNAs as well as the role of miRNAs in signaling under ethylene stimulation in the rubber tree. In this study, hbr-miR159 and hbr-miR166 were down-regulated in bark under ethylene treatment. The ethylene also down-regulated ATHB15-like (Class III Homeodomain Leucine Zipper, HD-ZIP III) which have been extensively implicated in the regulation of primary and secondary vascular tissue pattern formation. The strong negative-regulation of ARF6/ARF8 caused by hbr-miR167 involved in an attenuation of vascular development and may gradually lead to bark dryness syndrome in the long term ethylene treatment. The negative correlation of hbr-miR172 and its target REF3 in the inner soft bark under ethylene treatment results in dramatic increases in latex yield in the ethylene-sensitive clone of the rubber tree. The overall results suggested that the differential expression of HD-ZIP III, miR167/ARF6, ARF8, and miR172/REF3 and related genes may play possible roles in the response to ethylene treatment, resulting in longer latex flow and increased latex yield.


      PubDate: 2014-10-12T03:06:44Z
       
  • The roles of histone acetylation in seed performance and plant development
    • Abstract: Publication date: November 2014
      Source:Plant Physiology and Biochemistry, Volume 84
      Author(s): Zhi Wang , Hong Cao , Fengying Chen , Yongxiu Liu
      Histone acetylation regulates gene transcription by chromatin modifications and plays a crucial role in the plant development and response to environment cues. The homeostasis of histone acetylation is controlled by histone acetyltransferases (HATs) and histone deacetylases (HDACs) in different plant tissues and development stages. The vigorous knowledge of the function and co-factors about HATs (e.g. GCN5) and HDACs (e.g. HDA19, HDA6) has been obtained from model plant Arabidopsis. However, understanding individual role of other HATs and HDACs require more work, especially in the major food crops such as rice, maize and wheat. Many co-regulators have been recently identified to function as a component of HAT or HDAC complex in some specific developmental processes. The described findings show a distinctive and interesting epigenetic regulation network composed of HATs, HDACs and co-regulators playing crucial roles in the seed performance, flowering time, plant morphogenesis, plant response to stresses etc. In this review, we summarized the recent progresses and suggested the perspective of histone acetylation research, which might provide us a new window to understand the epigenetic code of plant development and to improve the crop production and quality.
      Graphical abstract image

      PubDate: 2014-10-12T03:06:44Z
       
  • 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
       
  • 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
       
  • 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
       
  • 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
       
  • 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
       
  • 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
       
 
 
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