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Journal Cover Plant Physiology and Biochemistry
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   Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 0981-9428
     Published by Elsevier Homepage  [2573 journals]   [SJR: 0.996]   [H-I: 63]
  • BdBRD1, a brassinosteroid C-6 oxidase homolog in Brachypodium distachyon
           L., is required for multiple organ development
    • Abstract: Publication date: Available online 20 November 2014
      Source:Plant Physiology and Biochemistry
      Author(s): Yi Xu , Xia Zhang , Qi Li , Zhiyuan Cheng , Haijuan Lou , Lei Ge , Hailong An
      Brassinosteroids (BRs), known as a kind of phytohormones, play essential roles in plant growth and development. Although the studies on the BR biosynthesis and signaling are extensive in Arabidopsis, little is known in temperate cereals. In this study, bdbrd1-1, a T-DNA insertion mutant from Brachypodium distachyon, was isolated and characterized in details. The bdbrd1-1 mutant showed lots of cellular and morphogenetic defects, including shortened cell shapes, severe dwarfing, twisted leaves and sterile spikes. Sequencing the flanking fragment of the T-DNA and complementation by genomic DNA in the mutant, confirmed that the developmental defects are caused by the T-DNA insertion in BdBRD1, a possible brassinosteroid C-6 oxidase gene. Application of 24-epicastasterone could partly rescue the bdbrd1-1 dwarfing phenotype. Expression analysis of BdBRD1 suggested that bdbrd1-1 is probably a null mutant and its wild type transcript is expressed in various tissues and highest in the leaf sheaths. Meanwhile, measurements on leaf numbers of the main stems or days to the emergence of the inflorescences suggested that bdbrd1-1 is late-flowering. The late-flowering phenotype could be converted by vernalization treatment, although there lacks a typical FLC gene in B. distachyon. The current data provide an insight into the relationship between BRs biosynthesis and individual development in B. distachyon, an emerging model plant for the temperate cereals.


      PubDate: 2014-11-24T05:42:16Z
       
  • Enhanced accumulation of carotenoids in sweetpotato plants overexpressing
           IbOr-Ins gene in purple-fleshed sweetpotato cultivar
    • Abstract: Publication date: Available online 20 November 2014
      Source:Plant Physiology and Biochemistry
      Author(s): Sung-Chul Park , Sun Ha Kim , Seyeon Park , Hyeong-Un Lee , Joon Seol Lee , Woo Sung Park , Mi-Jeong Ahn , Yun-Hee Kim , Jae Cheol Jeong , Haeng-Soon Lee , Sang-Soo Kwak
      Sweetpotato [Ipomoea batatas (L.) Lam] is an important root crop that produces low molecular weight antioxidants such as carotenoids and anthocyanin. The sweetpotato orange (IbOr) protein is involved in the accumulation of carotenoids. To increase the levels of carotenoids in the storage roots of sweetpotato, we generated transgenic sweetpotato plants overexpressing IbOr-Ins under the control of the cauliflower mosaic virus (CaMV) 35S promoter in an anthocyanin-rich purple-fleshed cultivar (referred to as IbOr plants). IbOr plants exhibited increased carotenoid levels (up to 7-fold) in their storage roots compared to wild type (WT) plants, as revealed by HPLC analysis. The carotenoid contents of IbOr plants were positively correlated with IbOr transcript levels. The levels of zeaxanthin were ∼12 times elevated in IbOr plants, whereas β-carotene increased ∼1.75 times higher than those of WT. Quantitative RT-PCR analysis revealed that most carotenoid biosynthetic pathway genes were up-regulated in the IbOr plants, including PDS, ZDS, LCY-β, CHY-β, ZEP and Pftf, whereas LCY-ɛ was down-regulated. Interestingly, CCD1, CCD4 and NCED, which are related to the degradation of carotenoids, were also up-regulated in the IbOr plants. Anthocyanin contents and transcription levels of associated biosynthetic genes seemed to be altered in the IbOr plants. The yields of storage roots and aerial parts of IbOr plants and WT plants were not significantly different under field cultivation. Taken together, these results indicate that overexpression of IbOr-Ins can increase the carotenoid contents of sweetpotato storage roots.


      PubDate: 2014-11-24T05:42:16Z
       
  • Understanding abiotic stress tolerance mechanisms in soybean: A
           
    • Abstract: Publication date: Available online 20 November 2014
      Source:Plant Physiology and Biochemistry
      Author(s): Raymond N. Mutava , Silvas Jebakumar Prince K. , Naeem Hasan Syed , Li Song , Babu Valliyodan , Wei Chen , Henry T. Nguyen
      Many sources of drought and flooding tolerance have been identified in soybean, however underlying molecular and physiological mechanisms are poorly understood. Therefore, it is important to illuminate different plant responses to these abiotic stresses with and understand the mechanisms that confer tolerance. Towards this goal we used four contrasting soybean (Glycine max) genotypes (PI 567690 – drought tolerant, Pana – drought susceptible, PI 408105A – flooding tolerant, S99-2281 – flooding susceptible) grown under greenhouse conditions and compared genotypic responses to drought and flooding at the physiological, biochemical, and cellular level. We also quantified these variations and tried to infer their role in drought and flooding tolerance in soybean. Our results revealed that different mechanisms contribute to reduction in net photosynthesis under drought and flooding stress. Under drought stress, ABA and stomatal conductance are responsible for reduced photosynthetic rate; while under flooding stress, accumulation of starch granules played a major role. Drought tolerant genotypes PI 567690 and PI 408105A had higher plastoglobule numbers than the susceptible Pana and S99-2281. Drought stress increased the number and size of plastoglobules in most of the genotypes pointing to a possible role in stress tolerance. Interestingly, there were seven fibrillin proteins localized within the plastoglobules that were up-regulated in the drought and flooding tolerant genotypes PI 567690 and PI 408105A, respectively, but down-regulated in the drought susceptible genotype Pana. These results suggest a potential role of Fibrillin proteins, FBN1a, 1b and 7a in soybean response to drought and flooding stress.


      PubDate: 2014-11-24T05:42:16Z
       
  • Current status of the production of high temperature tolerant transgenic
           crops for cultivation in warmer climates
    • Abstract: Publication date: Available online 22 November 2014
      Source:Plant Physiology and Biochemistry
      Author(s): Dhruv Lavania , Anuradha Dhingra , Manzer H. Siddiqui , Mohamed H. Al-Whaibi , Anil Grover
      Climate change is resulting in heightened incidences of plant heat stress episodes. Production of transgenic crops with enhanced heat stress tolerance is a highly desired agronomic trait for the sustainability of food production in 21st century. We review the current status of our understanding of the high temperature stress response of plants. We specifically deliberate on the progress made in altering levels of heat shock proteins (Hsp100, Hsp70/Hsp40 and sHsps), heat shock factors and specific metabolic proteins in improving plant tolerance to heat stress by transgenic approach.


      PubDate: 2014-11-24T05:42:16Z
       
  • Effect of nitrogen and phosphorus deficiency on transcriptional regulation
           of genes encoding key enzymes of starch metabolism in duckweed (Landoltia
           punctata)
    • Abstract: Publication date: Available online 22 November 2014
      Source:Plant Physiology and Biochemistry
      Author(s): Zhao Zhao , Hui-juan Shi , Mao-lin Wang , Long Cui , Hai Zhao , Yun Zhao
      The production of starch by plants influences their use as biofuels. Nitrogen (N) and phosphorus (P) regulate starch gene expression during plant growth and development, yet the role of key enzymes such as ADP-glucose pyrophosphorylase (E.C. 2.7.7.27 AGPase) in starch metabolism during N- and P-deficiency remains unknown. We investigated the effect of N- and P-deficiency on the expression of large (LeAPL1, LeAPL2, and LeAPL3) and small (LeAPS) subunits of AGPase in duckweed (Landoltia punctata) and their correlation with starch content. We first isolated the full-length cDNA encoding LeAPL1 (GenBank Accession No. KJ603244) and LeAPS (GenBank Accession No. KJ603243); they contained open reading frames of 1554 bp (57.7-kDa polypeptide of 517 amino acids) and 1578 bp (57.0 kDa polypeptide of 525 amino acids), respectively. Real-time PCR analysis revealed that LeAPL1 and LeAPL3 were highly expressed during early stages of N-deficiency, while LeAPL2 was only expressed during late stage. However, in response to P-deficiency, LeAPL1 and LeAPL2 were upregulated during early stages and LeAPL3 was primarily expressed in the late stage. Interestingly, LeAPS was highly expressed following N-deficiency during both stages, but was only upregulated in the early stage after P-deficiency. The activities of AGPase and soluble starch synthesis enzyme (SSS EC 2.4.1.21) were positively correlated with changes in starch content. Furthermore, LeAPL3 and LeSSS (SSS gene) were positively correlated with changes in starch content during N-deficiency, while LeAPS and LeSSS were correlated with starch content in response to P-deficiency. These results elevate current knowledge of the molecular mechanisms underlying starch synthesis.


      PubDate: 2014-11-24T05:42:16Z
       
  • Identification of the expressed protein and the impact of change in
           ascorbate peroxidase activity related to endodormancy breaking in Pyrus
           pyrifolia
    • Abstract: Publication date: Available online 18 November 2014
      Source:Plant Physiology and Biochemistry
      Author(s): Yoshihiro Takemura , Katsuou Kuroki , Mingfeng Jiang , Kazuhiro Matsumoto , Fumio Tamura
      Endodormancy is an important feature of perennial deciduous fruit trees that survive in the extreme climates brought about by seasonal variation. To acquire a comprehensive knowledge of the biochemical processes occurring just before endodormancy breaking, the buds collected in the pre-breaking period (PP) phase were used as samples to identify the proteins related to the breaking of endodormancy in the Japanese pear (Pyrus pyrifolia Nakai). Using nano-ESI-LC-MS/MS analysis, 96 proteins were overlapped by analyses of three times and identified as expressed proteins at the PP stage. Among these proteins, dehydrin, several classes of heat shock proteins (HSP), auxin-binding protein, and auxin-induced protein were identified in the floral bud in the PP stage. The majority of these proteins were involved primarily in the oxidation-reduction process. We focused on catalase (CAT), peroxidase (POD), and ascorbate peroxidase (APX) as enzymes regulating the levels of hydrogen peroxide (H2O2) in the bud. From measurements taken during the deepest period (DP), PP, mid-breaking period (MP), and late-breaking period (LP) of endodormancy, CAT activity decreased gradually, while APX activity also decreased from DP to MP, but then increased rapidly during LP. Protein data for PP and the rapid increase in APX activity observed in LP provided knowledge of the biochemical processes that regulate the consecutive transition from endodormancy breaking to ecodormancy induction in the Japanese pear.
      Graphical abstract image

      PubDate: 2014-11-20T05:21:55Z
       
  • Response of NBS encoding resistance genes linked to both heat and fungal
           stress in Brassica oleracea
    • Abstract: Publication date: Available online 18 November 2014
      Source:Plant Physiology and Biochemistry
      Author(s): Young-Wook Kim , Hee-Jeong Jung , Jong-In Park , Yoonkang Hur , Ill-Sup Nou
      Environmental stresses, including both abiotic and biotic stresses, cause considerable yield loss in crops and can significantly affect their development. Under field conditions, crops are exposed to a variety of concurrent stresses. Among abiotic and biotic stresses, heat and Fusarium oxysporum, are the most important factors affecting development and yield productivity of Brassica oleracea. Genes encoding the nucleotide-binding site (NBS) motif are known to be related to responses to abiotic and biotic stresses in many plants. Hence, this study was conducted to characterize the NBS encoding genes obtained from transcriptome profiles of two cabbage genotypes with contrasting responses to heat stress, and to test expression levels of selected NBS- leucine reich repeat (LRR) genes in F. oxysporum infected plants. We selected 80 up-regulated genes from a total of 264 loci, among which 17 were confirmed to be complete and incomplete members of the TIR-NBS-LRR (TNL) class families, and another identified as an NFYA-HAP2 family member. Expression analysis using qRT-PCR revealed that eight genes showed significant responses to heat shock treatment and F. oxysporum infection. Additionally, in the commercial B. oleracea cultivars with resistance to F. oxysporum, the Bol007132, Bol016084, and Bol030522 genes showed dramatically higher expression in the F. oxysporum resistant line than in the intermediate and susceptible lines. The results of this study will facilitate the identification and the development of molecular markers based on multiple stress resistance genes related to heat and fungal stress under field conditions in B. oleracea.


      PubDate: 2014-11-20T05:21:55Z
       
  • Overexpression of wheat NF-YA10 gene regulates the salinity stress
           response in Arabidopsis thaliana
    • Abstract: Publication date: Available online 17 November 2014
      Source:Plant Physiology and Biochemistry
      Author(s): Xiaoyan Ma , Xinlei Zhu , Chunlong Li , Yinling Song , Wei Zhang , Guangmin Xia , Mei Wang
      The nuclear factor Y (NF-Y) transcription factor is formed by the interaction of three distinct subunits (NF-YA, -YB and -YC). It targets the CCAAT box, a common cis-element in eukaryotic promoters. Here, the bread wheat gene TaNF-YA10-1 has been isolated from the salinity tolerant cultivar SR3. Recombinant TaNF-YA10-1 was heterologously produced in Escherichia coli, and the purified protein successfully bound to the CCAAT motif in vitro. TaNF-YA10-1 was down-regulated by the imposition of salinity and abscisic acid (ABA). The constitutive expression of TaNF-YA10-1 in Arabidopsis thaliana significantly increased the plant's sensitivity to salinity and repressed its sensitivity to ABA as judged from the seed germination, cotyledon greening and the relative root growth. The transcription of stress-related genes AtRAB18, AtRD29B, AtABI5, AtCBF1 and AtCBF3 was downregulated in TaNF-YA10-1 overexpression transgenic plants. The data provide supportive evidence that TaNFYA10-1 is involved in the regulation of growth under salinity stress conditions.


      PubDate: 2014-11-20T05:21:55Z
       
  • Identification and expression analysis of rice histone genes
    • Abstract: Publication date: Available online 18 November 2014
      Source:Plant Physiology and Biochemistry
      Author(s): Yongfeng Hu , Yan Lai
      Histones, acting as the core of nucleosome, are the chief protein component of chromatin. They play an important role in gene regulation by covalent modification at several sites and histone variants replacement. Five major families of histones exist: H1, H2A, H2B, H3 and H4. The protein sequences within each family appear to be highly conserved. In this paper, we identified 60 histone proteins in rice (Oryza sativa) including 14 H2A, 15 H2B, 16 H3, 11 H4 and 4 H1. Sequence analysis indicates that histone protein sequences in plant are more variable than in animal. Interestingly, we found a rice-specific H4 variant which showed several amino acid substitutions with canonical protein and was expressed in different tissues in a low level. Expression analysis indicates that a subset of histone genes were expressed in a similar pattern and many of them responded to stress conditions. Specifically, we found that two H2A.Z genes were down-regulated by stress in leaves but not in roots suggesting that they might be involved in stress response.


      PubDate: 2014-11-20T05:21:55Z
       
  • Rediscovering leaf optical properties: New insights into plant acclimation
           to solar UV radiation
    • Abstract: Publication date: Available online 18 November 2014
      Source:Plant Physiology and Biochemistry
      Author(s): Paul W. Barnes , Stephan D. Flint , Ronald J. Ryel , Mark A. Tobler , Anne Barkley , Jason J. Wargent
      The accumulation of UV-absorbing compounds (flavonoids and other phenylpropanoid derivatives) and resultant decrease in the UV transmittance of the epidermis in leaves (TUV), is a primary protective mechanism against the potentially deleterious effects of UV radiation and is a critical component of the overall acclimation response of plants to changing UV environments. Traditional measurements of TUV were laborious, time-consuming and destructive or invasive, thus limiting their ability to efficiently make multiple measurements of the optical properties of plants in the field. The development of rapid, nondestructive optical methods of determining TUV has permitted the examination of UV optical properties of leaves with increased replication, on a finer time scale, and enabled repeated sampling of the same leaf over time. This technology has therefore allowed for studies examining acclimation responses to UV in plants in ways not previously possible. Here we provide a brief review of these earlier studies examining leaf UV optical properties and some of their important contributions, describe the principles by which the newer non-invasive measurements of epidermal UV transmittance are made, and highlight several case studies that reveal how this technique is providing new insights into this UV acclimation response in plants, which is far more plastic and dynamic than previously thought.


      PubDate: 2014-11-20T05:21:55Z
       
  • Metabolite profiling elucidates communalities and differences in the
           polyphenol biosynthetic pathways of red and white Muscat genotypes
    • Abstract: Publication date: Available online 15 November 2014
      Source:Plant Physiology and Biochemistry
      Author(s): Asfaw Degu , Caterina Morcia , Giorgio Tumino , Uri Hochberg , David Toubiana , Fulvio Mattivi , Anna Schneider , Polina Bosca , Luigi Cattivelli , Valeria Terzi , Aaron Fait
      The chemical composition of grape berries is varietal dependent and influenced by the environment and viticulture practices. In Muscat grapes, phenolic compounds play a significant role in the organoleptic property of the wine. In the present study, we investigated the chemical diversity of berries in a Muscat collection. Metabolite profiling was performed on 18 Moscato bianco clones and 43 different red and white grape varieties of Muscat using ultra-performance liquid chromatography–quadrupole time of flight–mass spectrometry (UPLC-QTOF-MS/MS) coupled with SNP genotyping. Principle component analysis and hierarchical clustering showed a separation of the genotypes into six main groups, three red and three white. Anthocyanins mainly explained the variance between the different groups. Additionally, within the white varieties mainly flavonols and flavanols contributed to the chemical diversity identified. A genotype-specific rootstock effect was identified when separately analyzing the skin of the clones, and it was attributed mainly to resveratrol, quercetin 3-O-galactoside, citrate and malate. The metabolite profile of the varieties investigated reveals the chemical diversity existing among different groups of Muscat genotypes. The distribution pattern of metabolites among the groups dictates the abundance of precursors and intermediate metabolite classes, which contribute to the organoleptic properties of Muscat berries.


      PubDate: 2014-11-16T05:08:49Z
       
  • Early growth promotion and leaf level physiology changes in Burkholderia
           phytofirmans strain PsJN inoculated switchgrass
    • Abstract: Publication date: Available online 15 November 2014
      Source:Plant Physiology and Biochemistry
      Author(s): Bingxue Wang , Chuansheng Mei , John R. Seiler
      Switchgrass (SG) is one of the most promising next generation biofuel crops in North America. Inoculation with bacterial endophytes has improved growth of several plant species. Our study demonstrated that Burkholderia phytofirmans strain PsJN, a well-studied plant growth promoting rhizo-bacterium (PGPR) significantly increased both aboveground and belowground biomass (DW) and promoted elongation of root, stem and leaf within 17 days following inoculation. Furthermore, the enhanced root growth in PsJN inoculated plants lagged behind the shoot response, resulting in greater allocation to aboveground growth (p = 0.0041). Lower specific root length (SRL, p = 0.0158) and higher specific leaf weight (SLW, p = 0.0029) were also observed in PsJN inoculated seedlings, indicating changes in development. Photosynthetic rates (Ps) were also significantly higher in PsJN inoculated seedlings after 17 days (54%, p = 0.0016), and this occurred initially without increases in stomatal conductance resulting in significantly greater water use efficiency (WUE, 37.7%, p = 0.0467) and lower non-stomatal limitation (LNS, 29.6%, p = 0.0222). These rapid changes in leaf level physiology are at least partially responsible for the growth enhancement due to PsJN.


      PubDate: 2014-11-16T05:08:49Z
       
  • Zn deficiency in Brassica napus induces Mo and Mn accumulation associated
           with chloroplast proteins variation without Zn remobilization
    • Abstract: Publication date: Available online 6 November 2014
      Source:Plant Physiology and Biochemistry
      Author(s): Vincent Billard , Anne Maillard , Maria Garnica , Florence Cruz , José-Maria Garcia-Mina , Jean-Claude Yvin , Alain Ourry , Philippe Etienne
      The importance of zinc (Zn) has been of little concern in human nutrition despite a strong decrease of this element in crops since the rise of high yielding varieties. For better food quality, Zn biofortification can be used, but will be optimal only if mechanisms governing Zn management are better known. Using Zn deficiency, we are able to demonstrate that Zn is not remobilized in Brassica napus (B. napus). Thus, remobilization processes should not be targeted by biofortification strategies. This study also complemented previous work by investigating leaf responses to Zn deficiency, especially from proteomic and ionomic points of view, showing for example, an increase in Manganese (Mn) content and of the Mn-dependent protein, Oxygen Evolving Enhancer.


      PubDate: 2014-11-08T04:27:20Z
       
  • Plant stress analysis: Application of prompt, delayed chlorophyll
           fluorescence and 820 nm modulated reflectance. Insights from
           independent experiments
    • Abstract: Publication date: Available online 4 November 2014
      Source:Plant Physiology and Biochemistry
      Author(s): Elisabetta Salvatori , Lina Fusaro , Elena Gottardini , Martina Pollastrini , Vasilij Goltsev , Reto J. Strasser , Filippo Bussotti
      Nine short-term independent studies were carried out with two M-PEA units on several plant species differing in their functional traits (woody evergreen, woody deciduous, herbaceous) and exposed to different kind of abiotic stress (drought, salt, ozone, UV radiation). Aim of the study is to check the consistency of plant responses, assessed through three sets of simultaneously measured signals: Prompt Fluorescence (PF), Delayed Fluorescence (DF) and Modulated Reflectance of 820 nm light (MR). The decrease of F V/F M and F 0, the increase of V J and V I were the most common responses related to PF parameters. The decrease of v ox and v red as well the increase of MRmin were common response of MR. DF showed species-treatment specific behaviours. The Principal Component Analysis (PCA) suggests that the combination of PF and MR parameters represents a powerful tool for plant stress phenotyping, whereas MR parameters are linked to physiological strategies, related to different functional groups, to cope with stress factors.
      Graphical abstract image

      PubDate: 2014-11-08T04:27:20Z
       
  • Proteomics of seed development, desiccation tolerance, germination and
           vigor
    • Abstract: Publication date: Available online 4 November 2014
      Source:Plant Physiology and Biochemistry
      Author(s): Wei-Qing Wang , Shu-Jun Liu , Song-Quan Song , Ian Max Møller
      Proteomics, the large-scale study of the total complement of proteins in a given sample, has been applied to all aspects of seed biology mainly using model species such as Arabidopsis or important agricultural crops such as corn and rice. Proteins extracted from the sample have typically been separated and quantified by 2-dimensional polyacrylamide gel electrophoresis followed by liquid chromatography and mass spectrometry to identify the proteins in the gel spots. In this way, qualitative and quantitative changes in the proteome during seed development, desiccation tolerance, germination, dormancy release, vigor alteration and responses to environmental factors have all been studied. Many proteins or biological processes potentially important for each seed process have been highlighted by these studies, which greatly expands our knowledge of seed biology. Proteins that have been identified to be particularly important for at least two of the seed processes are involved in detoxification of reactive oxygen species, the cytoskeleton, glycolysis, protein biosynthesis, post-translational modifications, methionine metabolism, and late embryogenesis-abundant (LEA) proteins. It will be useful for molecular biologists and molecular plant breeders to identify and study genes encoding particularly interesting target proteins with the aim to improve the yield, stress tolerance or other critical properties of our crop species.


      PubDate: 2014-11-08T04:27:20Z
       
  • The effects of salt stress cause a diversion of basal metabolism in barley
           roots: possible different roles for glucose-6-phosphate dehydrogenase
           isoforms
    • Abstract: Publication date: Available online 4 November 2014
      Source:Plant Physiology and Biochemistry
      Author(s): Manuela Cardi , Daniela Castiglia , Myriam Ferrara , Gea Guerriero , Maurizio Chiurazzi , Sergio Esposito
      In this study the effects of salt stress and nitrogen assimilation have been investigated in roots of hydroponically-grown barley plants exposed to 150 mM NaCl, in presence or absence of ammonium as the sole nitrogen source. Salt stress determines a diversion of root metabolism towards the synthesis of osmolytes, such as glycine betaine and proline, and increased levels of reduced glutathione. The metabolic changes triggered by salt stress result in a decrease in both activities and protein abundance of key enzymes, namely GOGAT and PEP carboxylase, and in a slight increase in HSP70. These variations would enhance the requirement for reductants supplied by the OPPP, consistently with the observed increase in total G6PDH activity. The involvement and occurrence of the different G6PDH isoforms have been investigated, and the kinetic properties of partially purified cytosolic and plastidial G6PDHs determined. Bioinformatic analyses examining co-expression profiles of G6PDHs in Arabidopsis and barley corroborate the data presented. Moreover, the gene coding for the root P2-G6PDH isoform was fully sequenced; the biochemical properties of the corresponding protein were examined experimentally. The results are discussed in the light of the possible distinct roles and regulation of the different G6PDH isoforms during salt stress in barley roots.


      PubDate: 2014-11-08T04:27:20Z
       
  • Involvement of ethylene in sex expression and female flower development in
           watermelon (Citrullus lanatus)
    • Abstract: Publication date: Available online 4 November 2014
      Source:Plant Physiology and Biochemistry
      Author(s): Susana Manzano , Cecilia Martínez , Juan Manuel García , Zoraida Megías , Manuel Jamilena
      Although it is known that ethylene has a masculinizing effect on watermelon, the specific role of this hormone in sex expression and flower development has not been analyzed in depth. By using different approaches the present work demonstrates that ethylene regulates differentially two sex-related developmental processes: sexual expression, i.e. the earliness and the number of female flowers per plant, and the development of individual floral buds. Ethylene production in the shoot apex as well as in male, female and bisexual flowers demonstrated that the female flower requires much more ethylene than the male one to develop, and that bisexual flowers result from a decrease in ethylene production in the female floral bud. The occurrence of bisexual flowers was found to be associated with elevated temperatures in the greenhouse, concomitantly with a reduction of ethylene production in the shoot apex. External treatments with ethephon and AVG, and the use of Cucurbita rootstocks with different ethylene production and sensitivity, confirmed that, as occurs in other cucurbit species, ethylene is required to arrest the development of stamens in the female flower. Nevertheless, in watermelon ethylene inhibits the transition from male to female flowering and reduces the number of pistillate flowers per plant, which runs contrary to findings in other cucurbit species. The use of Cucurbita rootstocks with elevated ethylene production delayed the production of female flowers but reduced the number of bisexual flowers, which is associated with a reduced fruit set and altered fruit shape.
      Graphical abstract image

      PubDate: 2014-11-08T04:27:20Z
       
  • Effects of UV-B radiation on anatomical characteristics, phenolic
           compounds and gene expression of the phenylpropanoid pathway in highbush
           blueberry leaves
    • Abstract: Publication date: Available online 1 November 2014
      Source:Plant Physiology and Biochemistry
      Author(s): Claudio Inostroza-Blancheteau , Marjorie Reyes-Díaz , Alejandro Arellano , Mirtha Latsague , Patricio Acevedo , Rodrigo Loyola , Patricio Arce-Johnson , Miren Alberdi
      The effects of increased doses of UV-B radiation on anatomical, biochemical and molecular features of leaves of two highbush blueberry (Vaccinium corymbosum L. cv. Brigitta and Bluegold) genotypes were investigated. Plants were grown in a solid substrate and exposed to 0, 0.07, 0.12 and 0.19 W m−2 of biologically effective UV-B radiation for up to 72 h. Leaf thickness and the adaxial epidermis thickness fell more than 3-fold in both genotypes at the highest UV-B dose. Moreover, in Bluegold an evident disorganization in the different cell layers was observed at the highest UV-B radiation. A significant decrease in chlorophyll a/b after 6 h in Brigitta under the greater UV-B doses was observed. Anthocyanin and total phenolics were increased, especially at 0.19 W m−2, when compared to the control in both genotypes. Chlorogenic acid was the most abundant hydroxycinnamic acid in Brigitta, and was significantly higher (P ≤ 0.05) than in Bluegold leaves. Regarding the expression of phenylpropanoid genes, only the transcription factor VcMYBPA1 showed a significant and sustained induction at higher doses of UV-B radiation in both genotypes compared to the controls. Thus, the reduction of leaf thickness concomitant with a lower lipid peroxidation and rapid enhancement of secondary metabolites, accompanied by a stable induction of the VcMYBPA1 transcription factor suggest a better performance against UV-B radiation of the Brigitta genotype.


      PubDate: 2014-11-04T04:10:18Z
       
  • Editorial Board
    • Abstract: Publication date: November 2014
      Source:Plant Physiology and Biochemistry, Volume 84




      PubDate: 2014-10-31T03:55:22Z
       
  • Effect of desiccation on the dynamics of genome-wide DNA methylation in
           orthodox seeds of Acer platanoides L
    • Abstract: Publication date: Available online 30 October 2014
      Source:Plant Physiology and Biochemistry
      Author(s): Beata P. Plitta , Marcin Michalak , Barbara Bujarska-Borkowska , Mirosława Z. Barciszewska , Jan Barciszewski , Paweł Chmielarz
      5-methylcytosine, an abundant epigenetic mark, plays an important role in the regulation of plant growth and development, but there is little information about stress-induced changes in DNA methylation in seeds. In the present study, changes in a global level of m5C were measured in orthodox seeds of Acer platanoides L. during seed desiccation from a WC of 1.04 to 0.05–0.06 g H2O·g−1 dry mass (g·g−1). Changes in the level of DNA methylation were measured using 2D TLC – based method. Quality of desiccated seeds was examined by germination and seedling emergence tests. Global m5C content (R 2) increase was observed in embryonic axes isolated from seeds collected at a high WC of 1.04 g·g−1 after their desiccation to significantly lower WC of 0.17 and 0.19 g·g−1. Further desiccation of these seeds to a WC of 0.06 g·g−1, however, resulted in a significant DNA demethylation to R 2 = 11.52–12.22%. Similar m5C decrease was observed in seeds which undergo maturation drying on the tree and had four times lower initial WC of 0.27 g· g−1 at the time of harvest, as they were dried to a WC of 0.05 g·g−1. These data confirm that desiccation induces changes in seed m5C levels. Results were validated by seed lots derived from tree different A. platanoides provenances. It is plausible that sine wave-like alterations in m5C amount may represent a specific response of orthodox seeds to drying and play a relevant role in desiccation tolerance in seeds.


      PubDate: 2014-10-31T03:55:22Z
       
  • Functional reconstitution of a rice aquaporin water channel, PIP1;1, by a
           micro-batchwise methodology
    • Abstract: Publication date: Available online 30 October 2014
      Source:Plant Physiology and Biochemistry
      Author(s): Vito Scalera , Patrizia Gena , Maria Mastrodonato , Yoshichika Kitagawa , Salvatore Carulli , Maria Svelto , Giuseppe Calamita
      Assessing the selectivity, regulation and physiological relevance of aquaporin membrane channels (AQPs) requires structural and functional studies of wild type and modified proteins. In particular, when characterizing their transport properties, reconstitution in isolation from native cellular or membrane processes is of pivotal importance. Here, we describe rapid and efficient incorporation of OsPIP1; 1, a rice AQP, in liposomes at analytical scale. PIP1; 1 was produced as a histidine-tagged form, 10His-OsPIP1; 1, in an Escherichia coli-based expression system. The recombinant protein was purified by affinity chromatography and incorporated into liposomes by a micro-batchwise technology using egg-yolk phospholipids and the non-polar Amberlite resin. PIP1; 1 proteoliposomes and control empty liposomes had good size homogeneity as seen by quasi-elastic light scattering and electron microscopy analyses. By stopped-flow light scattering, indicating correct protein folding of the incorporated protein, the osmotic water permeability exhibited by the PIP1; 1 proteoliposomes was markedly higher than empty liposomes. Functional reconstitution of OsPIP1; 1 was further confirmed by the low Arrhenius activation energy (3.37 kcal/mol) and sensitivity to HgCl2, a known AQP blocker, of the PIP1; 1-mediated osmotic water conductance. These results provide a valuable contribution in fully elucidating the regulation and water-conducting property of PIP1; 1, an AQP that needs to hetero-multimerize with AQPs of the PIP2 subgroup to reach the native plasma membrane and play its role. The micro-batchwise methodology is suitable for the functional reconstitution of whichever AQPs and other membrane transport proteins.


      PubDate: 2014-10-31T03:55:22Z
       
  • Aluminum stress inhibits root growth and alters physiological and
           metabolic responses in chickpea (Cicer arietinum L.)
    • Abstract: Publication date: Available online 22 October 2014
      Source:Plant Physiology and Biochemistry
      Author(s): Shuvasish Choudhury , Parul Sharma
      Chickpea (Cicer arietinum L.) roots were treated with aluminum (Al3+) in calcium chloride (CaCl2) solution (pH 4.7) and growth responses along with physiological and metabolic changes were investigated. Al3+ treatment for 7d resulted in a dose dependent decline of seed germination and inhibition of root growth. A significant (p ≤ 0.05) decline in fresh and dry biomass were observed after 7d of Al3+ stress. The root growth (length) was inhibited after 24 and 48 h of stress imposition. The hydrogen peroxide (H2O2) levels increased significantly (p ≤ 0.05) with respect to control in Al3+ treated roots. The hematoxylin and Evans blue assay indicated significant (p ≤ 0.05) accumulation of Al3+ in the roots and loss of plasmamembrane integrity respectively. The time-course evaluation of lipid peroxidation showed increase in malondialdehyde (MDA) after 12, 24 and 48 h of stress imposition. Al3+ treatment did not alter the MDA levels after 2 or 4 h of stress, however, a minor increase was observed after 6 and 10 h of treatment. The proton (1H) nuclear magnetic resonance (NMR) spectrum of the perchloric acid extracts showed variation in the abundance of metabolites and suggested a major metabolic shift in chickpea root during Al3+ stress. The key differences that were observed include changes in energy metabolites. Accumulation of phenolic compounds suggested its possible role in Al3+ exclusion in roots during stress. The results suggested that Al3+ alters growth pattern in chickpea and induces reactive oxygen species (ROS) production that causes physiological and metabolic changes.


      PubDate: 2014-10-27T03:48:15Z
       
  • Xanthomonas campestris lipooligosaccharides trigger innate immunity and
           oxidative burst in Arabidopsis
    • Abstract: Publication date: Available online 22 October 2014
      Source:Plant Physiology and Biochemistry
      Author(s): S. Proietti , C. Giangrande , A. Amoresano , P. Pucci , A. Molinaro , L. Bertini , C. Caporale , C. Caruso
      Plants lack the adaptive immunity mechanisms of jawed vertebrates, so they rely on innate immune responses to defense themselves from pathogens. The plant immune system perceives the presence of pathogens by recognition of molecules known as pathogen-associated molecular patterns (PAMPs). PAMPs have several common characteristics, including highly conserved structures, essential for the microorganism but absent in host organisms. Plants can specifically recognize PAMPs using a large set of receptors and can respond with appropriate defenses by activating a multicomponent and multilayered response. Lipopolysaccharides (LPSs) and lipooligosaccharides (LOSs) are major components of the cell surface of Gram-negative bacteria with diverse roles in bacterial pathogenesis of animals and plants that include elicitation of host defenses. Little is known on the mechanisms of perception of these molecules by plants and the associated signal transduction pathways that trigger plant immunity. Here we addressed the question whether the defense signaling pathway in Arabidopsis thaliana was triggered by LOS from Xanthomonas campestris pv. campestris (Xcc), using proteomic and transcriptomic approaches. By using affinity capture strategies with immobilized LOS and LC-MS/MS analyses, we identified 8 putative LOS protein ligands. Further investigation of these interactors led to the definition that LOS challenge is able to activate a signal transduction pathway that uses nodal regulators in common with salicylic acid-mediated pathway. Moreover, we proved evidence that Xcc LOS are responsible for oxidative burst in Arabidopsis either in infiltrated or systemic leaves. In addition, gene expression studies highlighted the presence of gene network involved in reactive oxygen species transduction pathway.


      PubDate: 2014-10-27T03:48:15Z
       
  • 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
       
  • 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
       
  • 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
       
  • 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
       
  • 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
       
 
 
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