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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  [2563 journals]   [SJR: 0.996]   [H-I: 63]
  • Beneficial rhizobacteria from rice rhizosphere confers high protection
           against biotic and abiotic stress inducing systemic resistance in rice
           seedlings
    • Abstract: Publication date: September 2014
      Source:Plant Physiology and Biochemistry, Volume 82
      Author(s): Jose Antonio Lucas , Jorge García-Cristobal , Alfonso Bonilla , Beatriz Ramos , Javier Gutierrez-Mañero
      The present study reports a screening for PGPR in a highly selective environment, the rhizosphere of rice plants, in southwestern of Spain. Among the 900 isolates, only 38% were positive for at least one of the biochemical activities to detect putative PGPR. The best 80 isolates were selected and identified by 16S rRNA partial sequencing. Among these, 13 strains were selected for growth promotion assays. Only one strain (BaC1-38) was able to significantly increase height, while nine strains significantly inhibited it. Five strains significantly increased dry weight, and only BaC1-21 significantly decreased it. Based on significant modifications in growth, three bacteria (BaC1-13, BaC1-21 and BaC1-38) were tested for systemic induction of resistance against stress challenge (salt and Xanthomonas campestris infection). Protection against salt stress and pathogen infection was similar; BaC1-38 protected by 80%, BaC1-13 by 50% and BaC1-21 only by 20%. Toxicity of salt stress to the plants was evaluated by photosynthetic efficiency of seedlings. Fv/Fm only decreased significantly in plants inoculated with BaC1-13. ΦPSII also decreased significantly in plants inoculated with BaC1-21, but increased significantly with BaC1-38. NPQ decreased significantly in plants inoculated with BaC1-21. The two strains able to induce systemic resistance against Xanthomonas campestris seem to work by different pathways. BaC1-13 primed enzymes related with the detoxification of reactive oxygen species (ROS). However, BaC1-38 primed pathogenesis-related proteins (PRs), and this pathway was more effective, both improved chlorophyll index confirming the priming state of the plant.


      PubDate: 2014-06-08T14:52:08Z
       
  • Hydrogen peroxide-induced antioxidant activities and cardiotonic glycoside
           accumulation in callus cultures of endemic Digitalis species
    • Abstract: Publication date: September 2014
      Source:Plant Physiology and Biochemistry, Volume 82
      Author(s): Gunce Sahin Cingoz , Sandeep Kumar Verma , Ekrem Gurel
      The effect of hydrogen peroxide (H2O2) on callus cultures of four Digitalis species (Digitalis lamarckii, Digitalis trojana, Digitalis davisiana and Digitalis cariensis) increased catalase (CAT), superoxide dismutase (SOD), total phenolic, proline activity and cardiotonic glycoside production. Callus derived from hypocotyl explants was cultured on Murashige and Skoog medium supplemented with 0.25 mg L−1 indole-3-acetic acid (IAA) and 0.5 mg L−1 thidiazuron (TDZ). After a month of culture, callus was transferred to MS medium containing 10 mM H2O2 and then incubated for 6 h. The amount of five cardenolides (Lanatoside C, Digitoxin, Digoxigenin, Gitoxigenin and Digoxin) as well as CAT, SOD, total phenolic, proline activity from Digitalis species were compared. No digoxin was detected in all treatments and control groups. The total cardenolides estimated were in the order of D. lamarckii (586.65  μg g−1 dw), D. davisiana (506.79 μg g−1 dw), D. cariensis (376.60 μg g−1 dw) and D. trojana (282.39 μg g−1 dw). It was clear that H2O2 pre-treatment resulted in an increase in enzymatic and nonenzymatic antioxidants. However, a significant negative relationship between cardenolides production and overall activities of CAT, SOD, total phenolic and proline was evident. The described protocol here will be useful for the development of new strategies for a large-scale production of cardenolides.


      PubDate: 2014-06-08T14:52:08Z
       
  • Cold priming drives the sub-cellular antioxidant systems to protect
           photosynthetic electron transport against subsequent low temperature
           stress in winter wheat
    • Abstract: Publication date: September 2014
      Source:Plant Physiology and Biochemistry, Volume 82
      Author(s): Xiangnan Li , Jian Cai , Fulai Liu , Tingbo Dai , Weixing Cao , Dong Jiang
      Low temperature seriously depresses the growth of wheat through inhibition of photosynthesis, while earlier cold priming may enhance the tolerance of plants to subsequent low temperature stress. Here, winter wheat plants were firstly cold primed (5.2 °C lower temperature than the ambient temperature, viz., 10.0 °C) at the Zadoks growth stage 28 (i.e. re-greening stage, starting on 20th of March) for 7 d, and after 14 d of recovery the plants were subsequently subjected to a 5 d low temperature stress (8.4 °C lower than the ambient temperature, viz., 14.1 °C) at the Zadoks growth stage 31 (i.e. jointing stage, starting on 8th April). Compared to the non-primed plants, the cold-primed plants possessed more effective oxygen scavenging systems in chloroplasts and mitochondria as exemplified by the increased activities of SOD, APX and CAT, resulting in a better maintenance in homeostasis of ROS production. The trapped energy flux (TR O /CS O ) and electron transport (ET O /CS O ) in the photosynthetic apparatus were found functioning well in the cold-primed plants leading to higher photosynthetic rate during the subsequent low temperature stress. Collectively, the results indicate that cold priming activated the sub-cellular antioxidant systems, depressing the oxidative burst in photosynthetic apparatus, hereby enhanced the tolerance to subsequent low temperature stress in winter wheat plants.


      PubDate: 2014-06-08T14:52:08Z
       
  • Reactive oxygen species burst induced by aluminum stress triggers
           mitochondria-dependent programmed cell death in peanut root tip cells
    • Abstract: Publication date: September 2014
      Source:Plant Physiology and Biochemistry, Volume 82
      Author(s): Wenjing Huang , Xudong Yang , Shaochang Yao , Thet LwinOo , Huyi He , Aiqin Wang , Chuangzhen Li , Longfei He
      Recent studies had certified that aluminum (Al) induced ROS production and programmed cell death (PCD) in higher plants. The relationship between ROS production and PCD occurrence under Al stress is uncovered. The results showed that root elongation inhibition and PCD occurrence was induced by 100 μM AlCl3. Al stress induced ROS burst, up-regulated Rboh and COX gene expression, increased mitochondrial permeability transition pore (MPTP) opening, decreased inner mitochondrial membrane potential (ΔΨm), released cytochrome c from mitochondria to cytoplasm, activated caspase 3-like protease activity. Exogenous H2O2 aggravated the changes caused by Al and accelerated PCD occurrence, but ROS scavenger CAT and AsA reversed the changes caused by Al and inhibited PCD production. A potential cascade of cellular events during Al induced PCD via mitochondria dependent pathway and the mechanism of ROS on regulating PCD induced by Al is proposed.


      PubDate: 2014-06-08T14:52:08Z
       
  • Effect of leaf dehydration duration and dehydration degree on PSII
           photochemical activity of papaya leaves
    • Abstract: Publication date: September 2014
      Source:Plant Physiology and Biochemistry, Volume 82
      Author(s): Meijun Liu , Zishan Zhang , Huiyuan Gao , Cheng Yang , Xingli Fan , Dandan Cheng
      Although the effect of dehydration on photosynthetic apparatus has been widely studied, the respective effect of dehydration duration and dehydration degree was neglected. This study showed that, when leaves dehydrated in air, the PSII activities of leaves decreased with the decline of leaf relative water content (RWC). Unexpectedly, when leaves dehydrated to same RWC, the decreases in Fv/Fm, Ψo and RC/CSm were lower in leaves dehydrating at 43 °C than those at 25 °C. However, to reach the same RWC, leaves dehydrating at 43 °C experienced 1/6 of the dehydration duration for leaves dehydrating at 25 °C. To distinguish the respective effect of dehydration degree and dehydration duration on photosynthetic apparatus, we studied the PSII activities of leaves treated with different concentration of PEG solutions. Increasing dehydration degree aggravated the decline of Fv/Fm, Ψo and RC/CSm in leaves with the same dehydration duration, while prolonging the dehydration duration also exacerbated the decline of Fv/Fm, Ψo and RC/CSm in leaves with identical dehydration degree. With the same dehydration degree and duration, high temperature enhanced the decrease of Fv/Fm, Ψo and RC/CSm in the leaves. When leaves dehydrated in air, the effect of high temperature was underestimated due to reduction of dehydration duration. The results demonstrated that, dehydration degree and duration both play important roles in damage to photosynthetic apparatus. We suggest that, under combined stresses, the effects of dehydration degree and duration on plants should be considered comprehensively, otherwise, partial or incorrect results may be obtained.
      Graphical abstract image

      PubDate: 2014-06-08T14:52:08Z
       
  • Different mechanisms drive the performance of native and invasive woody
           species in response to leaf phosphorus supply during periods of drought
           stress and recovery
    • Abstract: Publication date: September 2014
      Source:Plant Physiology and Biochemistry, Volume 82
      Author(s): Marciel Teixeira Oliveira , Camila Dias Medeiros , Gabriella Frosi , Mauro Guida Santos
      The effects of drought stress and leaf phosphorus (Pi) supply on photosynthetic metabolism in woody tropical species are not known, and given the recent global environmental change models that forecast lower precipitation rates and periods of prolonged drought in tropical areas, this type of study is increasingly important. The effects of controlled drought stress and Pi supply on potted young plants of two woody species, Anadenanthera colubrina (native) and Prosopis juliflora (invasive), were determined by analyzing leaf photosynthetic metabolism, biochemical properties and water potential. In the maximum stress, both species showed higher leaf water potential (Ψl) in the treatment drought +Pi when compared with the respective control −Pi. The native species showed higher gas exchange under drought +Pi than under drought –Pi conditions, while the invasive species showed the same values between drought +Pi and −Pi. Drought affected the photochemical part of photosynthetic machinery more in the invasive species than in the native species. The invasive species showed higher leaf amino acid content and a lower leaf total protein content in both Pi treatments with drought. The two species showed different responses to the leaf Pi supply under water stress for several variables measured. In addition, the strong resilience of leaf gas exchange in the invasive species compared to the native species during the recovery period may be the result of higher efficiency of Pi use. The implications of this behavior for the success of this invasive species in semiarid environments are discussed.


      PubDate: 2014-06-08T14:52:08Z
       
  • Wound healing response and xylem differentiation in tobacco plants
           over-expressing a fungal endopolygalacturonase is mediated by copper amine
           oxidase activity
    • Abstract: Publication date: September 2014
      Source:Plant Physiology and Biochemistry, Volume 82
      Author(s): Alessandra Cona , Alessandra Tisi , Sandip Annasaheb Ghuge , Stefano Franchi , Giulia De Lorenzo , Riccardo Angelini
      In this work, we have investigated the involvement of copper amine oxidase (CuAO; EC 1.4.3.21) in wound healing and xylem differentiation of Nicotiana tabacum plants over-expressing a fungal endopolygalacturonase (PG plants), which show constitutively activated defence responses. In petioles and stems of PG plants, we found higher CuAO activity and lower polyamine (PA) levels, particularly putrescine (Put), with respect to wild-type (WT) plants. Upon wounding, a more intense autofluorescence of cell wall phenolics was observed in correspondence of wound surface, extending to epidermis and cortical parenchima only in PG plants. This response was mostly dependent on CuAO activity, as suggested by the reversion of autofluorescence upon supply of 2-bromoethylamine (2-BrEt), a CuAO specific inhibitor. Moreover, in unwounded plants, histochemical analysis revealed a tissue-specific expression of the enzyme in the vascular cambium and neighboring derivative cells of both petioles and stems of PG plants, whereas the corresponding WT tissues appeared unstained or faintly stained. A higher histochemical CuAO activity was also observed in xylem cells of PG plants as compared to WT xylem tissues suggesting a peculiar role of CuAO activity in xylem differentiation in PG plants. Indeed, roots of PG plants exhibited early xylem differentiation, a phenotype consistent with both the higher CuAO and the lower Put levels observed and supported by the 2-BrEt-mediated reversion of early root xylem differentiation and H2O2 accumulation. These results strongly support the relevance of PA-catabolism derived H2O2 in defence responses, such as those signaled by a compromised status of cell wall pectin integrity.


      PubDate: 2014-06-08T14:52:08Z
       
  • Differential expression of molybdenum transport and assimilation genes
           between two winter wheat cultivars (Triticum aestivum)
    • Abstract: Publication date: September 2014
      Source:Plant Physiology and Biochemistry, Volume 82
      Author(s): Zhaojun Nie , Chengxiao Hu , Hongen Liu , Qiling Tan , Xuecheng Sun
      Molybdenum (Mo) is an essential trace element for higher plants. Winter wheat cultivar 97003 has a higher Mo efficiency than 97014 under Mo-deficiency stress. Mo efficiency is related to Mo uptake, transfer and assimilation in plants. Several genes are involved in regulating Mo uptake, transfer and assimilation in plants. To obtain a better understanding of the aforementioned difference in Mo uptake, we have conducted a hydroponic trail to investigate the expression of genes related to Mo uptake, transfer and assimilation in the above two cultivars. The results indicate a closed relationship between Mo uptake and TaSultr5.1, TaSultr5.2 and TaCnx1 expression, according to a stepwise regression analysis of the time course of Mo uptake in the two cultivars. Meanwhile, expression of TaSultr5.2 in roots also showed a positive relationship with Mo uptake rates. 97003 had stronger Mo uptake than 97014 at low Mo-application rates (less than 1 μmol Mo L−1) due to the higher expression of TaSultr5.2, TaSultr5.1 and TaCnx1 in roots. On the contrary, Mo uptake of 97003 was weaker than 97014 at high Mo application rates (ranging from 5 to 20 μmol Mo L−1), which was related to significant down-regulation of TaSultr5.2 and TaCnx1 genes in roots of 97003 compared to 97014. Therefore, we speculated that the differential-expression intensities of TaSultr5.2, TaSultr5.1 and TaCnx1 could be the cause of the difference in Mo uptake between the two winter wheat cultivars at low and high Mo application levels.


      PubDate: 2014-06-02T14:26:04Z
       
  • Editorial Board
    • Abstract: Publication date: July 2014
      Source:Plant Physiology and Biochemistry, Volume 80




      PubDate: 2014-06-02T14:26:04Z
       
  • Polyamine biosynthesis and degradation are modulated by exogenous
           gamma-aminobutyric acid in root-zone hypoxia-stressed melon roots
    • Abstract: Publication date: September 2014
      Source:Plant Physiology and Biochemistry, Volume 82
      Author(s): Chunyan Wang , Longquan Fan , Hongbo Gao , Xiaolei Wu , Jingrui Li , Guiyun Lv , Binbin Gong
      We detected physiological change and gene expression related to PA metabolism in melon roots under controlled and hypoxic conditions with or without 5 mM GABA. Roots with hypoxia treatment showed a significant increase in glutamate decarboxylase (GAD) activity and endogenous GABA concentration. Concurrently, PA biosynthesis and degradation accelerated with higher gene expression and enzymes activity. However, endogenous GABA concentrations showed a large and rapid increase in Hypoxia + GABA treated roots. This led to a marked increase in Glu concentration by feedback inhibition of GAD activity. Hypoxia + GABA treatment enhanced arginine (Arg), ornithine (Orn) and methionine (Met) levels, promoting enzyme gene expression levels and arginine decarboxylase (ADC), ornithine decarboxylase (ODC) and S-adenosylmethionine decarboxylase (SAMDC) activities in roots. Hypoxia + GABA treatment significantly increased concentrations of free putrescine (Put), spermidine (Spd) and spermine (Spm) from day two to eight, promoting the PA conversion to soluble conjugated and insoluble bound forms. However, PA degradation was significantly inhibited in hypoxia + GABA treated roots by significantly decreasing gene expression and activity of diamine oxidase (DAO) and polyamine oxidase (PAO). However, exogenous GABA showed a reduced effect in control compared with hypoxic conditions. Our data suggest that alleviating effect of exogenous GABA to hypoxia is closely associated with physiological regulation of PA metabolism. We propose a potential negative feedback mechanism of higher endogenous GABA levels from combined effects of hypoxia and exogenous GABA, which alleviate the hypoxia damage by accelerating PA biosynthesis and conversion as well as preventing PA degradation in melon plants.


      PubDate: 2014-05-26T10:02:24Z
       
  • The role of isoflavone metabolism in plant protection depends on
           the rhizobacterial MAMP that triggers systemic resistance against
           Xanthomonas axonopodis pv. glycines in Glycine max (L.) Merr. cv. Osumi
    • Abstract: Publication date: September 2014
      Source:Plant Physiology and Biochemistry, Volume 82
      Author(s): Elena Algar , F. Javier Gutierrez-Mañero , Ana Garcia-Villaraco , Daniel García-Seco , J. Antonio Lucas , Beatriz Ramos-Solano
      Glycine max (L.) Merr. plays a crucial role in both the field of food and the pharmaceutical industry due to their input as plant protein and to the benefits of isoflavones (IF) for health. In addition, IF play a key role in nodulation and plant defense and therefore, an increase in IF would be desirable for better field performance. IF are secondary metabolites and therefore, inducible, so finding effective agents to increase IF contents is interesting. Among these agents, plant growth promoting rhizobacteria (PGPR) have been used to trigger systemic induction of plant's secondary metabolism through their microbe associated molecular patterns (MAMPs) that fit in the plant's receptors to start a systemic response. The aim of this study was to evaluate the ability of 4 PGPR that had a contrasted effect on IF metabolism, to protect plants against biotic stress and to establish the relation between IF profile and the systemic response triggered by the bacteria. Apparently, the response involves a lower sensitivity to ethylene and despite the decrease in effective photosynthesis, growth is only compromised in the case of M84, the most effective in protection. All strains protected soybean against Xanthomonas axonopodis pv. glycines (M84 > N5.18 > Aur9>N21.4) and only M84 and N5.18 involved IF. N5.18 stimulated accumulation of IF before pathogen challenge. M84 caused a significant increase on IF only after pathogen challenge and N21.4 caused a significant increase on IF content irrespective of pathogen challenge. Aur9 did not affect IF. These results point out that all 4 strains have MAMPs that trigger defensive metabolism in soybean. Protection induced by N21.4 and Aur9 involves other metabolites different to IF and the role of IF in defence depends on the previous metabolic status of the plant and on the bacterial MAMP.


      PubDate: 2014-05-26T10:02:24Z
       
  • The rice gene OsZFP6 functions in multiple stress tolerance responses in
           yeast and Arabidopsis
    • Abstract: Publication date: September 2014
      Source:Plant Physiology and Biochemistry, Volume 82
      Author(s): Qing-jie Guan , Li-feng Wang , Qing-yun Bu , Zhen-yu Wang
      The role of zinc finger proteins in organismal stress conditions has been widely reported. However, little is known concerning the function of CCHC-type zinc finger proteins in rice. In this study, OsZFP6, a rice CCHC-type zinc finger protein 6 gene, was cloned from rice using RT-PCR. The OsZFP6 protein contains 305 amino acids and a conserved zinc finger domain and is localised to the nucleus. Southern blot analysis revealed that a single copy was encoded in the rice genome. OsZFP6 expression was increased by abiotic stress, including salt (NaCl), alkali (NaHCO3) and H2O2 treatment. When OsZFP6 was transformed into yeast, the transgenic yeast showed significantly increased resistance to NaHCO3 compared to the control. Moreover, Arabidopsis transgenic plants overexpressing OsZFP6 were more tolerant to both NaHCO3 and H2O2 treatments. Overall, we uncovered a role for OsZFP6 in abiotic stress responses and identified OsZFP6 as a putatively useful gene for developing crops with increased alkali and H2O2 tolerance.


      PubDate: 2014-05-26T10:02:24Z
       
  • Heterology expression of the tomato LeLhcb2 gene confers elevated
           tolerance to chilling stress in transgenic tobacco
    • Abstract: Publication date: July 2014
      Source:Plant Physiology and Biochemistry, Volume 80
      Author(s): Yong-Sheng Deng , Fan-Ying Kong , Bin Zhou , Song Zhang , Meng-Meng Yue , Qing-Wei Meng
      Chilling is one of the most serious environmental stresses that disrupt the metabolic balance of cells and enhance the production of reactive oxygen species (ROS). Light harvesting complex (LHC) proteins had a function in dissipating excess excitation energy and eliminating ROS to maintain the normal physiological function of cells. A tomato (Lycopersicon esculentum) LHC antenna protein gene (LeLhcb2) was isolated. The LeLhcb2-green fluorescent protein (GFP) fusion protein was targeted to the chloroplast of Arabidopsis mesophyll protoplast. Quantitative real-time polymerase chain reaction (qRT-PCR) analysis indicated that the expression of LeLhcb2 was markedly abundant in leaves and was induced by chilling (4 °C). qRT-PCR analysis and western blot confirmed that the sense gene LeLhcb2 was transferred into tobacco genome and overexpressed. Under chilling stress, the transgenic plants showed not only better growth, higher fresh weight, chlorophyll content, but also lower malondialdehyde (MDA) accumulation and relative electrical conductivity (REC), compared with the wild type (WT). The maximal photochemical efficiency of PSII (Fv/Fm), non-photochemical quenching (NPQ) and D1 protein content were also higher in the transgenic plants. Furthermore, the relatively lower hydrogen peroxide (H2O2) and superoxide radical ( O 2 − ) levels in the sense plants were not considered to due to the higher activity of ascorbate peroxidase (APX) and superoxide dismutase (SOD). These results suggested that the overexpression of LeLhcb2 had a key function in alleviating photo-oxidation of PSII and enhanced transgenic tobacco tolerance to chilling stress.


      PubDate: 2014-05-21T06:35:16Z
       
  • Fine mapping of the lesion mimic and early senescence 1 (lmes1)
           in rice (Oryza sativa)
    • Abstract: Publication date: July 2014
      Source:Plant Physiology and Biochemistry, Volume 80
      Author(s): Zhi Li , Yingxin Zhang , Lin Liu , Qunen Liu , Zhenzhen Bi , Ning Yu , Shihua Cheng , Liyong Cao
      A novel rice mutant, lesion mimic and early senescence 1 (lmes1), was induced from the rice 93-11 cultivar in a γ-ray field. This mutant exhibited spontaneous disease-like lesions in the absence of pathogen attack at the beginning of the tillering stage. Moreover, at the booting stage, lmes1 mutants exhibited a significantly increased MDA but decreased chlorophyll content, soluble protein content and photosynthetic rate in the leaves, which are indicative of an early senescence phenotype. The lmes1 mutant was significantly more resistant than 93-11 against rice bacterial blight infection, which was consistent with a marked increase in the expression of three resistance-related genes. Here, we employed a map-based cloning approach to finely map the lmes1 gene. In an initial mapping with 94 F2 individuals derived from a cross between the lmes1 mutant and Nipponbare, the lmes1 gene was located in a 10.6-cM region on the telomere of the long arm of chromosome 7 using simple sequence repeat (SSR) markers. To finely map lmes1, we derived two F2 populations with 940 individuals from two crosses between the lmes1 mutant and two japonica rice varieties, Nipponbare and 02428. Finally, the lmes1 gene was mapped to an 88-kb region between two newly developed inDel markers, Zl-3 and Zl-22, which harbored 15 ORFs.


      PubDate: 2014-05-15T18:05:35Z
       
  • Plant hormones in defense response of Brassica napus to Sclerotinia
           sclerotiorum – Reassessing the role of salicylic acid in the
           interaction with a necrotroph
    • Abstract: Publication date: July 2014
      Source:Plant Physiology and Biochemistry, Volume 80
      Author(s): Miroslava Nováková , Vladimír Šašek , Petre I. Dobrev , Olga Valentová , Lenka Burketová
      According to general model, jasmonic acid (JA) and ethylene (ET) signaling pathways are induced in Arabidopsis after an attack of necrotroph, Sclerotinia sclerotiorum (Lib.) de Bary. However, abscisic acid (ABA) and salicylic acid (SA) also seem to play a role. While signaling events in Arabidopsis have been intensively studied recently, information for the natural host Brassica napus is limited. In this study, multiple plant hormone quantification and expression analysis of marker genes of the signaling pathways was used to gain a complete view of the interaction of B. napus with S. sclerotiorum. Strong response of ET biosynthetic gene ACS2 was observed, accompanied by increases of SA and JA levels that correspond to the elevated expression of marker genes PR1 and LOX3. Interestingly, the level of ABA and the expression of its marker gene RD26 were also elevated. Furthermore, induction of the SA-dependent defense decreased disease symptoms. In addition, SA signaling is suggested as a possible target for manipulation by S. sclerotiorum. A gene for putative chorismate mutase SS1G_14320 was identified that is highly expressed during infection but not in vitro. Our results bring the evidence of SA involvement in the interaction of plant with the necrotroph that conflict with the current model.


      PubDate: 2014-05-15T18:05:35Z
       
  • Water-stress-induced inhibition of α-tubulin gene expression during
           growth, and its implications for reproductive success in rice
    • Abstract: Publication date: July 2014
      Source:Plant Physiology and Biochemistry, Volume 80
      Author(s): Inder S. Sheoran , Priyum Koonjul , Jihad Attieh , Hargurdeep S. Saini
      A drought-suppressed cDNA (RiP-3), encoding a putative α-tubulin protein was isolated from rice panicle at pollen-mother-cell meiosis stage. Analysis of its deduced amino acid sequence showed all the typical structural motifs for plant α-tubulins. The expression of α-tubulin transcripts was observed in all the reproductive organs of rice panicle, and in 5- or 15-day old seedlings, but not in mature leaves. Expression levels were positively correlated with the regions and periods of high growth, and the transcript level declined in parallel with drought-induced reduction in growth rates in all tissues examined. Immunoblot analysis of proteins separated by SDS-PAGE with anti-α-tubulin monoclonal antibody showed that the level of protein paralleled the changes in the transcript abundance in these organs. In situ immunolocalization of the α-tubulin protein in sections of the basal part of 5-day old seedlings showed that the highest levels of the protein were associated with the fastest growing leaf whorls, and the protein level declined upon a brief episode of water stress. Given the known critical role of tubulin in cell division and elongation, the results indicate that the expression of α-tubulin gene may be part of the events that suppress panicle elongation during water deficit, which is in turn a suspected cause of male reproductive failure and yield reduction in rice.


      PubDate: 2014-05-10T21:47:09Z
       
  • Base substitution mutations in uridinediphosphate-dependent
           glycosyltransferase 76G1 gene of Stevia rebaudiana causes the low levels
           of rebaudioside A Mutations in UGT76G1, A key gene of steviol glycosides
           synthesis
    • Abstract: Publication date: July 2014
      Source:Plant Physiology and Biochemistry, Volume 80
      Author(s): Yong-heng Yang , Su-zhen Huang , Yu-lin Han , Hai-yan Yuan , Chun-sun Gu , Yan-hai Zhao
      Steviol glycosides, extracted from the leaves of Stevia rebaudiana (Bert) Bertoni, are calorie-free sugar substitute of natural origin with intensely sweet (Boileau et al., 2012). Stevioside and rebaudioside A are the two main kinds of the diterpenic glycosides. We analyzed the concentration of stevioside and rebaudioside A in Stevia leaves of about 500 samples (hybrid progenies) and discovered a mutation plant “Z05” with very low levels of rebaudioside A. Because UGT76G1, a uridinediphosphate-dependent glycosyltransferases, is responsible for the conversion from stevioside to rebaudioside A (Richman et al., 2005), so mutation identification was done by sequencing the candidate gene, UGT76G1. In this study molecular analysis of two strains revealed a heterozygotic nonsense mutation of c.389T > G (p.L121X) in UGT76G1. Meanwhile, we found some amino acid substitutions significant change the protein structure. And the difference of enzyme activity between two strains proved the lack of functionality of UGT76G1 of the mutation “Z05”. So the nonsense mutation and amino acid substitution mutation resulted in the low levels of rebaudioside A.


      PubDate: 2014-05-10T21:47:09Z
       
  • The desiccation tolerant secrets of Selaginella lepidophylla: What we have
           learned so far'
    • Abstract: Publication date: July 2014
      Source:Plant Physiology and Biochemistry, Volume 80
      Author(s): Suzana Pampurova , Patrick Van Dijck
      Selaginella lepidophylla is a desiccation tolerant plant able to survive complete vegetative tissue dehydration and revive (‘resurrect’) in water conditions. Vegetative desiccation tolerance is an adaptive feature acquired by S. lepidophylla to withstand the long dry periods in its natural habitat, the Chihuahuan desert. Understanding the molecular basis of its drought stress tolerance may be of great benefit to help in developing novel strategies for improvement of drought stress tolerance in crops. Cell biological (e.g. gene discovery, comparative EST analysis, proteomics, metabolite profiling), ultrastructural and physiological studies have brought modest but already important insights in the desiccation tolerance mechanisms adapted by S. lepidophylla. Until recently, the desiccation tolerant mechanism of S. lepidophylla was related to its high trehalose levels. However, large-scale comparative metabolic analysis between S. lepidophylla and its desiccation susceptible relative Selaginella moellendorffii, unexpectedly revealed that S. moellendorffii contains higher trehalose levels than S. lepidophylla. Interestingly, polyols, such as sorbitol and xylitol are 100× more abundant in S. lepidophylla compared to S. moellendorffii. Whether this is linked to the higher stress tolerance remains to be established. Apart from these metabolites, we will also discuss the ultrastructural features that seem to play an important role in the desiccation tolerance of S. lepidophylla. Finally we discuss desiccation tolerance mechanism in other plant species.


      PubDate: 2014-05-10T21:47:09Z
       
  • Silicon-mediated changes in polyamine and 1-aminocyclopropane-1-carboxylic
           acid are involved in silicon-induced drought resistance in Sorghum bicolor
           L
    • Abstract: Publication date: July 2014
      Source:Plant Physiology and Biochemistry, Volume 80
      Author(s): Lina Yin , Shiwen Wang , Peng Liu , Wenhua Wang , Dan Cao , Xiping Deng , Suiqi Zhang
      The fact that silicon application alleviates drought stress has been widely reported, but the mechanism it underlying remains unclear. Here, morphologic and physiological changes were investigated in sorghum (Sorghum bicolor L.) seedlings treated with silicon and exposed to PEG-simulated drought stress for seven days. Drought stress dramatically decreased growth parameters (biomass, root/shoot ratio, leaf area, chlorophyll concentration and photosynthetic rate), while silicon application reduced the drought-induced decreases in those parameters. Leaf relative water content and transpiration rate were maintained at high levels compared to those in seedlings without silicon. The soluble sugar contents were increased, but the proline contents and the osmotic potential were decreased, showing that osmotic adjustment did not contribute to the silicon induced-drought resistance. Furthermore, levels of both free and conjugated polyamines (PAs) levels, including putrescine, spermidine and spermine, were all found to be increased by silicon under drought stress both in leaf and root. Meanwhile, 1-aminocyclopropane-1-carboxylic acid (ACC), the precursor of ethylene, was markedly decreased by supplemental silicon. Several key PA synthesis genes were upregulated by silicon under drought stress. These results suggest that silicon improves sorghum drought resistance by mediating the balance of PAs and ethylene levels. In leaf, the increased PAs and decreased ACC help to retard leaf senescence. In root, the balance between PAs and ACC participates in the modulation of root plasticity, increases the root/shoot ratio, and contributes to an increase in water uptake. These results suggest that silicon increases drought resistance through regulating several important physiological processes in plants.


      PubDate: 2014-05-10T21:47:09Z
       
  • How reactive oxygen species and proline face stress together
    • Abstract: Publication date: July 2014
      Source:Plant Physiology and Biochemistry, Volume 80
      Author(s): Kilani Ben Rejeb , Chedly Abdelly , Arnould Savouré
      Reactive oxygen species (ROS) are continuously generated as a consequence of plant metabolic processes due to incomplete reduction of O2. Previously considered to be only toxic by-products of metabolism, ROS are now known to act as second messengers in intracellular signalling cascades to trigger tolerance of various abiotic and biotic stresses. The accumulation of proline is frequently observed during the exposure of plants to adverse environmental conditions. Interestingly proline metabolism may also contribute to ROS formation in mitochondria, which play notably a role in hypersensitive response in plants, life-span extension in worms and tumor suppression in animals. Here we review current knowledge about the regulation of proline metabolism in response to environmental constraints and highlight the key role of ROS in the regulation of this metabolism. The impact of proline on ROS generation is also investigated. Deciphering and integrating these relationships at the whole plant level will bring new perspectives on how plants adapt to environmental stresses.


      PubDate: 2014-05-10T21:47:09Z
       
  • Leaf micromorphology and sugar may contribute to differences in drought
           tolerance for two apple cultivars
    • Abstract: Publication date: July 2014
      Source:Plant Physiology and Biochemistry, Volume 80
      Author(s): Shan Wu , Dong Liang , Fengwang Ma
      Apple trees (Malus domestica L.) are often exposed to severe water stress in the summertime. We determined how levels of nonstructural carbohydrates (NC) changed in the leaves of two cultivars – drought-tolerant ‘QinGuan’ and drought-sensitive ‘NaganoFuji’ – when plants were subjected for 10 d to a sudden water deficit. Photosynthetic performance was investigated in terms of gas exchange and antioxidant enzyme activity. Two separate irrigation scenarios were tested with one-year-old plants grafted onto Malus hupehensis (Pamp.) Rehd. rootstock: 1) water applied to 75% field capacity (FC) (Control, CK) and 2) irrigation withheld to achieve <75% FC ranging from 30 to 75% (Treatment, T). At Days 0, 1, 2, 4, 6, and 10 of the experiment, we recorded net CO2 assimilation, stomatal conductance, leaf transpiration rates, and intercellular CO2 concentrations. All of those parameters showed decreases in plants from both stress scenarios, although those declines were not as dramatic in ‘QinGuan’. The photosynthetic rate reduced primarily because of stomatal closure. In both cultivars, water stress induced the accumulation of NC, especially sorbitol, suggesting that this polyol has a role in osmoregulation. The rise in sorbitol levels was much steeper in ‘QinGuan’. Likewise, the interaction between superoxide dismutase and peroxidase activities varied between cultivars. In ‘QinGuan’, the malondialdehyde concentration was much lower and more closely correlated with a high Suc/NC ratio when compared with ‘NaganoFuji’. Scanning electron microscopy revealed a drought-resisting apparent structure in ‘QinGuan’. Overall, our results from both external and internal examinations demonstrated that ‘QinGuan’ is more drought-tolerant than ‘NaganoFuji’.


      PubDate: 2014-05-10T21:47:09Z
       
  • Overexpression of OsMYB4P, an R2R3-type MYB transcriptional activator,
           increases phosphate acquisition in rice
    • Abstract: Publication date: July 2014
      Source:Plant Physiology and Biochemistry, Volume 80
      Author(s): Won Tae Yang , Dongwon Baek , Dae-Jin Yun , Woon Ha Hwang , Dong Soo Park , Min Hee Nam , Eun Sook Chung , Young Soo Chung , Young Byung Yi , Doh Hoon Kim
      R2R3 MYB transcription factors play regulatory roles in plant responses to various environmental stresses and nutrient deficiency. In this study, we isolated and designated OsMYB4P, an R2R3 MYB transcription factor, from rice (Oryza sativa L. ‘Dongjin’) under phosphate-deficient conditions. OsMYB4P was localized in the nucleus and acted as a transcriptional activator. Transcriptional levels of OsMYB4P in cell suspension, shoots, and roots of rice increased under phosphate-deficient conditions. Shoots and roots of OsMYB4P-overexpressing plants grew well in high- and phosphate-deficient conditions. In addition, root system architecture was altered considerably as a result of OsMYB4P overexpression. Under both phosphate-sufficient and -deficient conditions, more Pi accumulated in shoots and roots of OsMYB4P-overexpressing plants than in the wild type. Overexpression of OsMYB4P led to greater expression of Pi transporter-family proteins OsPT1, OsPT2, OsPT4, OsPT7, and OsPT8 in shoots, and to decreased or unchanged expression of these proteins in roots, with the exception of OsPT8. These results demonstrate that OsMYB4P may be associated with efficient utilization of Pi in rice through transcriptional activation of Pi homeostasis-related genes.


      PubDate: 2014-05-10T21:47:09Z
       
  • Herbivory responsive C2H2 zinc finger transcription factor protein StZFP2
           from potato
    • Abstract: Publication date: July 2014
      Source:Plant Physiology and Biochemistry, Volume 80
      Author(s): Susan D. Lawrence , Nicole G. Novak , Richard W. Jones , Robert R. Farrar Jr. , Michael B. Blackburn
      While C2H2 zinc finger transcription factors (TF) are often regulated by abiotic stress, their role during insect infestation has been overlooked. This study demonstrates that the transcripts of the zinc finger transcription factors StZFP1 and StZFP2 are induced in potato (Solanum tuberosum L.) upon infestation by either the generalist tobacco hornworm (THW, Manduca sexta L.) or the specialist Colorado potato beetle (CPB, Leptinotarsa decemlineata Say). StZFP1 has been previously characterized as conferring salt tolerance to transgenic tobacco and its transcript is induced by Phytophthora infestans and several abiotic stresses. StZFP2 has not been characterized previously, but contains the hallmarks of a C2H2 zinc finger TF, with two conserved zinc finger domains and DLN motif, which encodes a transcriptional repressor domain. Expression studies demonstrate that StZFP2 transcript is also induced by tobacco hornworm and Colorado potato beetle. These observations expand the role of the C2H2 transcription factor in potato to include the response to chewing insect pests.


      PubDate: 2014-05-10T21:47:09Z
       
  • Differential physiological and molecular response of barley genotypes to
           water deficit
    • Abstract: Publication date: July 2014
      Source:Plant Physiology and Biochemistry, Volume 80
      Author(s): Mateusz de Mezer , Anna Turska-Taraska , Zygmunt Kaczmarek , Katarzyna Glowacka , Barbara Swarcewicz , Tadeusz Rorat
      Changes in physiological parameters (relative water content (RWC), biomass, water use efficiency (WUE), net photosynthetic yield (P N) and quantum yield of PSII (F v/F m)), in proline and sugar content, and expression profile of genes reported to be associated with the barley response to water deficit, including LEA genes, NHX1, Hsdr4, BLT101 and genes encoding transcription factors (HvDREB1, HvABF1, HvABI5 and HvZIP1), were analyzed in seedlings of nine barley genotypes subjected to a progressive increase in water deficit. Seedlings of all genotypes wilted when the soil water content (SWC) declined from 65% (control conditions) to 10% (severe drought conditions), but recovered turgor within a few hours of re-watering. However, when severe drought conditions were prolonged for a week, large differences in survival characteristics were observed between genotypes after re-watering. Multivariate analysis of the changes in physiological and molecular characteristics allowed several different homogenous groups within the genotypes to be distinguished, depending on stress intensity. Furthermore, integration between the stress-response traits was found and was shown to vary depending on the genotype and the stress level. Based on analysis of physiological traits and survival characteristics, two barley genotypes with high adaptability to the stress conditions (cv. Saida and breeding line Cam/B1), and two with low adaptability (cv. Express and breeding line Harmal), were identified. In addition, only changes in expression of the genes HvZIP1, encoding a b-ZIP-type transcription factor, and Hsdr4, encoding a protein of unknown function, were shown to be linked with adaptability of barley to water deficit. In summary, physiological and molecular data revealed large, stress-level-dependent differences between the barley cultivars and breeding lines tested in their response to water deficit.


      PubDate: 2014-05-10T21:47:09Z
       
  • Arabidopsis thaliana peroxidases involved in lignin biosynthesis: In
           silico promoter analysis and hormonal regulation
    • Abstract: Publication date: July 2014
      Source:Plant Physiology and Biochemistry, Volume 80
      Author(s): Joaquín Herrero , Alberto Esteban Carrasco , José Miguel Zapata
      Phytohormones such as auxins, cytokinins, and brassinosteroids, act by means of a signaling cascade of transcription factors of the families NAC, MYB, AP2 (APETALA2), MADS and class III HD (homeodomain) Zip, regulating secondary growth. When the hormonal regulation of Zinnia elegans peroxidase (ZePrx), an enzyme involved in lignin biosynthesis, was studied, it was found that this peroxidase is sensitive to a plethora of hormones which control xylem lignification. In a previous study we sought Arabidopsis thaliana homologues to ZePrx. Peroxidases 4, 52, 49 and 72 are the four peroxidases that fulfill the restrictive conditions that a peroxidase involved in lignification must have. In the present study, we focus our attention on hormonal regulation in order to establish the minimal structural and regulatory elements contained in the promoter region which an AtPrx involved in lignification must have. The results indicate that of the four peroxidases selected in our previous study, the one most likely to be homologous to ZePrx is AtPrx52. The results suggest that hormones such as auxins, cytokinins and BRs directly regulate AtPrx52, and that the AtPrx52 promoter may be the target of the set of transcription factors (NAC, MYB, AP2 and class I and III HD Zip) which are up-regulated by these hormones during secondary growth. In addition, the AtPrx52 promoter contains multiple copies of all the putative cis-elements (the ACGT box, the OCS box, the OPAQ box, the L1BX, the MYCL box and the W box) known to confer regulation by NO and H2O2.


      PubDate: 2014-05-06T05:42:53Z
       
  • RING-type ubiquitin ligase McCPN1 catalyzes UBC8-dependent protein
           ubiquitination and interacts with Argonaute 4 in halophyte ice plant
    • Abstract: Publication date: July 2014
      Source:Plant Physiology and Biochemistry, Volume 80
      Author(s): Chang-Hua Li , Chih-Pin Chiang , Jun-Yi Yang , Chia-Jou Ma , Yu-Chan Chen , Hungchen Emilie Yen
      RING-type copines are a small family of plant-specific RING-type ubiquitin ligases. They contain an N-terminal myristoylation site for membrane anchoring, a central copine domain for substrate recognition, and a C-terminal RING domain for E2 docking. RING-type copine McCPN1 (copine1) from halophyte ice plant (Mesembryanthemum crystallinum L.) was previously identified from a salt-induced cDNA library. In this work, we characterize the activity, expression, and localization of McCPN1 in ice plant. An in vitro ubiquitination assay of McCPN1 was performed using two ice plant UBCs, McUBC1 and McUBC2, characterized from the same salt-induced cDNA library. The results showed that McUBC2, a member of the UBC8 family, stimulated the autoubiquitination activity of McCPN1, while McUBC1, a homolog of the UBC35 family, did not. The results indicate that McCPN1 has selective E2-dependent E3 ligase activity. We found that McCPN1 localizes primarily on the plasma membrane and in the nucleus of plant cells. Under salt stress, the accumulation of McCPN1 in the roots increases. A yeast two-hybrid screen was used to search for potential McCPN1-interacting partners using a library constructed from salt-stressed ice plants. Screening with full-length McCPN1 identified several independent clones containing partial Argonaute 4 (AGO4) sequence. Subsequent agro-infiltration, protoplast two-hybrid analysis, and bimolecular fluorescence complementation assay confirmed that McCPN1 and AGO4 interacted in vivo in the nucleus of plant cells. The possible involvement of a catalyzed degradation of AGO4 by McCPN1 in response to salt stress is discussed.


      PubDate: 2014-05-06T05:42:53Z
       
  • Interactive effect of brassinosteroids and cytokinins on growth,
           chlorophyll, monosaccharide and protein content in the green alga
           Chlorella vulgaris (Trebouxiophyceae)
    • Abstract: Publication date: July 2014
      Source:Plant Physiology and Biochemistry, Volume 80
      Author(s): Andrzej Bajguz , Alicja Piotrowska-Niczyporuk
      Interaction between brassinosteroids (BRs) (brassinolide, BL; 24-epibrassinolide, 24-epiBL; 28-homobrassinolide, 28-homoBL; castasterone, CS; 24-epicastasterone, 24-epiCS; 28-homocastasterone, 28-homoCS) and adenine- (trans-zeatin, tZ; kinetin, Kin) as well as phenylurea-type (1,3-diphenylurea, DPU) cytokinins (CKs) in the regulation of cell number, phytohormone level and the content of chlorophyll, monosaccharide and protein in unicellular green alga Chlorella vulgaris (Trebouxiophyceae) were examined. Chlorella vulgaris exhibited sensitivity to CKs in the following order of their stimulating properties: 10 nM tZ > 100 nM Kin >1 μM DPU. Exogenously applied BRs possessed the highest biological activity in algal cells at concentration of 10 nM. Among the BRs, BL was characterized by the highest activity, while 28-homoCS - by the lowest. The considerable increase in the level of all endogenous BRs by 27–46% was observed in C. vulgaris culture treated with exogenous 10 nM tZ. It can be speculated that CKs may stimulate BR activity in C. vulgaris by inducing the accumulation of endogenous BRs. CKs interacted synergistically with BRs increasing the number of cells and endogenous accumulation of proteins, chlorophylls and monosaccharides in C. vulgaris. The highest stimulation of algal growth and the contents of analyzed biochemical parameters were observed for BL applied in combination with tZ, whereas the lowest in the culture treated with both 28-homoCS and DPU. However, regardless of the applied mixture of BRs with CKs, the considerable increase in cell number and the metabolite accumulation was found above the level obtained in cultures treated with any single phytohormone in unicellular green alga C. vulgaris.


      PubDate: 2014-05-06T05:42:53Z
       
  • NADPH-dependent thioredoxin reductase A (NTRA) confers elevated tolerance
           to oxidative stress and drought
    • Abstract: Publication date: July 2014
      Source:Plant Physiology and Biochemistry, Volume 80
      Author(s): Joon-Yung Cha , Joo Yeon Kim , In Jung Jung , Mi Ri Kim , Andrew Melencion , Sadia Sabrina Alam , Dae-Jin Yun , Sang Yeol Lee , Min Gab Kim , Woe-Yeon Kim
      NADPH-dependent thioredoxin reductases (NTRs) are key-regulatory enzymes determining the redox state of the thioredoxin (Trx) system that provides reducing power to peroxidases or oxidoreductases. Moreover, it also plays an essential function in the direct reduction of ROS and acquiring stress tolerance in plant. Cytoplasmic NTRA, mitochondrial NTRB, and chloroplastic NTRC are the three conserved NTRs which cooperate with specific sub-cellularly localized Trxs in Arabidopsis. However, cytosolic NTRs such as NTRA in Arabidopsis have not previously been identified in plants or mammals as a source of functional redundancy with mitochondrial NTRs. Here, we show the involvement of NTRA in the plant stress response counteracting oxidative and drought stresses. Methyl viologen (MV), an inducer of oxidative stress in plants, enhanced the NTRA transcripts. To identify the physiological role of NTRA influencing ROS homeostasis by stress, NTRA overexpression (NTRAOX) and knock-out mutants (ntra-ko) were generated. After exposure to oxidative stress, wild-type and ntra-ko plants were sensitive, but NTRAOX plants tolerant. ROS range was increased by MV in wild-type and ntra-ko plants, but not in NTRAOX. Investigating the involvement of Arabidopsis NTRA in drought, NTRAOX plants exhibited extreme drought tolerance with high survival rates, lower water loss and reduced ROS compared to wild-type and ntra-ko plants. Transcripts of drought-responsive genes, such as RD29A and DREB2A, were highly expressed under drought and antioxidant genes, namely CuZnSOD and APX1 were enhanced in the absence of drought in NTRAOX plants. The results suggest that NTRA overexpression confers oxidative and drought tolerance by regulation of ROS amounts.


      PubDate: 2014-05-06T05:42:53Z
       
  • Arsenic stress in ri Redox consequences and regulation by iron
    • Abstract: Publication date: July 2014
      Source:Plant Physiology and Biochemistry, Volume 80
      Author(s): Shwetosmita Nath , Piyalee Panda , Sagarika Mishra , Mohitosh Dey , Shuvasish Choudhury , Lingaraj Sahoo , Sanjib Kumar Panda
      Arsenic (As) contamination is a serious hazard to human health and agriculture. It has emerged as an important threat for rice cultivation mainly in South Asian countries. In this study, we investigated the effect of iron (Fe) supplementation on arsenic (AsV) induced oxidative stress responses in rice (Oryza sativa L.). Rice seedlings treated with AsV for 24 and 48 h in presence or absence of 2.5 mM Fe after which the root and shoot tissues were harvested for analysis. The results indicate significant (p ≤ 0.05) reduction in root and shoot length/dry biomass. Supplementation of Fe showed improved growth responses under stress as compared to AsV alone. The scanning electron microscopy (SEM) analysis of roots under AsV treatment for 48 h showed major alterations in root structure and integrity, although no noticeable changes were observed in Fe – supplemented seedlings. Significantly high (p ≤ 0.05) accumulation of AsV was observed in root and shoot after 24 and 48 h of stress. However, under Fe – supplementation As accumulation in root and shoot were considerably low after 24 and 48 h of AsV treatment. The hydrogen peroxide (H2O2) and malondialdehyde (MDA) content in both root and shoot increased significantly (p ≤ 0.05) after 24 and 48 h of AsV treatment. In Fe – supplemented seedlings, the levels of H2O2 and MDA were considerably low as compared to AsV alone. Ascorbate (AsA) and glutathione (GSH) levels also increased significantly (p ≤ 0.05) under AsV stress as compared to control and Fe-supplemented seedlings. Activities of catalase (CAT) and superoxide dismutase (SOD) were significantly (p ≤ 0.05) high after 24 and 48 h of AsV treatment as compared to Fe-supplemented seedlings. The gene expression analysis revealed up-regulation of metallothionein (MT1, MT2) and nodulin 26-like intrinsic protein (NIP2;1) genes after 5d of As treatment, while their expressions were repressed under Fe-supplementation. Our results indicate that Fe regulates oxidative stress and promotes growth under As stress.


      PubDate: 2014-05-06T05:42:53Z
       
  • Bcl-2 suppresses activation of VPEs by inhibiting cytosolic Ca2+ level
           with elevated K+ efflux in NaCl-induced PCD in rice
    • Abstract: Publication date: July 2014
      Source:Plant Physiology and Biochemistry, Volume 80
      Author(s): Yongho Kim , Mingqiang Wang , Yu Bai , Zhanghui Zeng , Fu Guo , Ning Han , Hongwu Bian , Junhui Wang , Jianwei Pan , Muyuan Zhu
      Bcl-2 is one of the most important antiapoptotic members in mammals and prevents many forms of apoptosis in a variety of cell types. Our previous study revealed that overexpression of Bcl-2 significantly suppressed H2O2/NaCl-induced programmed cell death via inhibiting the transcriptional activation of OsVPE2 and OsVPE3 in transgenic rice. However, Ca2+ and K+ homeostasis of this process remains largely unknown. In the present study, we investigate whether nonselective cation channels (NSCC) blockers affect Bcl-2 function in rice under salt stress and how Bcl-2 affects ion homeostasis in salt stress-induced PCD. The results showed that overexpression of Bcl-2 significantly decreased transient elevations in the cytosolic Ca2+ levels, inhibited NaCl-induced K+ efflux but not H+ efflux across the plasma membrane, and further suppressed the expression levels of OsVPE2 and OsVPE3, leading to the inhibition of salt-induced PCD and increase of tolerance to salt stress in transgenic rice. During the NaCl-induced PCD, the effects of a NSCC blocker La3+ on ion homeostasis and VPEs expression in wild-type were similar to the effects of Bcl-2 overexpression in transgenic line. However, a synergistic effect of Bcl-2 and La3+ was not obviously detectable. Our results suggested that Bcl-2 played an important role in suppression of NaCl-induced PCD by disruption of ion homeostasis, providing an insight into the mechanistic study of plant VPEs, cytosolic Ca2+ level and K+ efflux.


      PubDate: 2014-05-06T05:42:53Z
       
  • Amelioration of high salinity stress damage by plant growth-promoting
           bacterial endophytes that contain ACC deaminase
    • Abstract: Publication date: July 2014
      Source:Plant Physiology and Biochemistry, Volume 80
      Author(s): Shimaila Ali , Trevor C. Charles , Bernard R. Glick
      Plant growth and productivity is negatively affected by soil salinity. However, it is predicted that plant growth-promoting bacterial (PGPB) endophytes that contain 1-aminocyclopropane-1-carboxylate (ACC) deaminase (E.C. 4.1.99.4) can facilitate plant growth and development in the presence of a number of different stresses. In present study, the ability of ACC deaminase containing PGPB endophytes Pseudomonas fluorescens YsS6, Pseudomonas migulae 8R6, and their ACC deaminase deficient mutants to promote tomato plant growth in the absence of salt and under two different levels of salt stress (165 mM and 185 mM) was assessed. It was evidence that wild-type bacterial endophytes (P. fluorescens YsS6 and P. migulae 8R6) promoted tomato plant growth significantly even in the absence of stress (salinity). Plants pretreated with wild-type ACC deaminase containing endophytic strains were healthier and grew to a much larger size under high salinity stress compared to plants pretreated with the ACC deaminase deficient mutants or no bacterial treatment (control). The plants pretreated with ACC deaminase containing bacterial endophytes exhibit higher fresh and dry biomass, higher chlorophyll contents, and a greater number of flowers and buds than the other treatments. Since the only difference between wild-type and mutant bacterial endophytes was ACC deaminase activity, it is concluded that this enzyme is directly responsible for the different behavior of tomato plants in response to salt stress. The use of PGPB endophytes with ACC deaminase activity has the potential to facilitate plant growth on land that is not normally suitable for the majority of crops due to their high salt contents.


      PubDate: 2014-05-01T04:10:04Z
       
  • Effective microorganisms enhance the scavenging capacity of the
           ascorbate–glutathione cycle in common bean (Phaseolus vulgaris L.)
           plants grown in salty soils
    • Abstract: Publication date: July 2014
      Source:Plant Physiology and Biochemistry, Volume 80
      Author(s): Neveen B. Talaat
      No information is available regarding effective microorganisms (EM) influence on the enzymatic and non-enzymatic antioxidant defence system involved in the ascorbate–glutathione cycle under saline conditions. Therefore, as a first approach, this article focuses on the contribution of EM to the scavenging capacity of the ascorbate–glutathione cycle in salt-stressed plants. It investigates some mechanisms underlying alleviation of salt toxicity by EM application. Phaseolus vulgaris cv. Nebraska plants were grown under non-saline or saline conditions (2.5 and 5.0 dSm−1) with and without EM application. Lipid peroxidation and H2O2 content were significantly increased in response to salinity, while they decreased with EM application in both stressed and non-stressed plants. Activities of ascorbate peroxidase (APX; EC 1.11.1.11) and glutathione reductase (GR; EC 1.6.4.2) increased under saline conditions; these increases were more significant in salt-stressed plants treated by EM. Activities of monodehydroascorbate reductase (MDHAR; EC 1.6.5.4) and dehydroascorbate reductase (DHAR; EC 1.8.5.1) decreased in response to salinity; however, they were significantly increased in stressed plants treated with EM. Ascorbate and glutathione contents were increased with the increasing salt concentration; moreover they further increased in stressed plants treated with EM. Ratios of AsA/DHA and GSH/GSSG decreased under saline conditions, whereas they were significantly increased with EM treatment in the presence or in the absence of soil salinization. The EM treatment detoxified the stress generated by salinity and significantly improved plant growth and productivity. Enhancing the H2O2-scavenging capacity of the ascorbate–glutathione cycle in EM-treated plants may be an efficient mechanism to attenuate the activation of plant defences.


      PubDate: 2014-04-26T04:24:53Z
       
  • Calcium involved in the poly(γ-glutamic acid)-mediated promotion of
           Chinese cabbage nitrogen metabolism
    • Abstract: Publication date: July 2014
      Source:Plant Physiology and Biochemistry, Volume 80
      Author(s): Zongqi Xu , Peng Lei , Xiaohai Feng , Xianju Xu , Jinfeng Liang , Bo Chi , Hong Xu
      Plant growth can reportedly be promoted by poly(γ-glutamic acid) (γ-PGA). However, the underlying mechanism is unknown. To reveal the mechanism of γ-PGA, we designed an experiment that investigated the effect of γ-PGA on the nitrogen metabolism of Chinese cabbage hydroponic cultured at different calcium (Ca) levels and varied exogenous Ca2+ inhibitors. The results showed that nitrate reductase (NR), glutamine synthetase (GS), glutamate synthase, and glutamate dehydrogenase activities in leaves and roots were obviously enhanced by γ-PGA at the normal Ca2+ level (4.0 mM). Meanwhile, γ-PGA increased the content of total nitrogen, soluble protein, and soluble amino acids in leaves. However, the promotional effect of γ-PGA on fresh weight weakened when Ca2+ was inadequate. Moreover, γ-PGA not only induced the influx of extracellular Ca2+ and Ca2+ in organelles into cytoplasm, but also increased the Ca2+-ATPase level to modify Ca2+ homeostasis in plant cells. In addition, exogenous Ca2+ inhibitors significantly suppressed the γ-PGA-mediated promotion of cytoplasmic free Ca2+ level, calmodulin (CaM) content, GS and glutamate dehydrogenase activities. In summary, γ-PGA accelerated the nitrogen metabolism of plants through the Ca2+/CaM signaling pathway, thereby improving the growth of the plant.


      PubDate: 2014-04-26T04:24:53Z
       
  • SnRK1 is differentially regulated in the cotyledon and embryo axe of bean
           (Phaseolus vulgaris L) seeds
    • Abstract: Publication date: July 2014
      Source:Plant Physiology and Biochemistry, Volume 80
      Author(s): Patricia Coello , Eleazar Martínez-Barajas
      SnRK1 activity is developmentally regulated in bean seeds and exhibits a transient increase with the highest value at 20 days after anthesis (DAA), which coincides with the beginning of protein and starch accumulation. The catalytic subunit of SnRK1 shows a consistent decrease throughout the seed development period. However, by 15 DAA a significant proportion of the catalytic subunit appears phosphorylated. The increase in activity and phosphorylation of the catalytic subunit coincides with a decrease in hexoses. However, SnRK1 activity is differentially regulated in the cotyledon and embryo axe, where a larger proportion of the catalytic subunit is phosphorylated. SnRK1 obtained from endosperm extract is inhibited by T6P and to a lesser extent by ADPG and UDPG, whereas the enzyme isolated from embryo is virtually insensitive to T6P but exhibits some inhibition by ADPG and UDPG. In cotyledon extracts, the effects of T6P and ADPG on SnRK1 activity are additive, whereas in embryo extract, T6P inhibits the enzyme only when ADPG is present. After fractionation on Sephacryl-S300, SnRK1 activity obtained from cotyledon extracts is detected as a single peak associated with a molecular weight of 250 kDa whereas that obtained form embryo axe extracts detected as 2 peaks associated with molecular weight of 250 and 180 kDa. In both cases, the catalytic subunit exhibits a wide distribution but is concentrated in the fractions with the highest activity. To analyse the composition of the complex, cotyledon and embryo extracts were treated with a reversible crosslinker (DSP). DSP induced the formation of complexes with molecular weights of 97 and 180 kDa in the cotyledon and embryo extracts, respectively. Since all the phosphorylated catalytic subunit is present in the complexes induced by DSP, it appears that the phosphorylation favors its interaction with other proteins.


      PubDate: 2014-04-26T04:24:53Z
       
  • MicroRNAs involving in cold, wounding and salt stresses in Triticum
           aestivum L.
    • Abstract: Publication date: July 2014
      Source:Plant Physiology and Biochemistry, Volume 80
      Author(s): Bing Wang , Yan-fei Sun , Na Song , Jin-ping Wei , Xiao-jie Wang , Hao Feng , Zhi-yuan Yin , Zhen-sheng Kang
      MicroRNAs (miRNAs) play critical roles in post-transcriptional regulation and act as important endogenous regulators to various stresses. Cold, wounding and high-salinity are three common environmental stress stimuli influencing crops growth and development. In this study, we identified 31 known miRNAs and 3 novel miRNAs in wheat. Moreover, 19 stress-regulated miRNAs using RT-qPCR data in which the effects of three stresses were surveyed from the known miRNAs. Among them, 16, 12 and 8 miRNAs were regulated under cold, wounding and high-salinity treatments, respectively. Of which 4 miRNAs were highly responsive to cold stress in wheat by northern blot, and 6 wounding-regulated and 3 high-salinity-regulated miRNAs were detected. Meanwhile, miR159, miR393 and miR398 were responsive to multiple stress stimuli. Besides, 2 novel miRNAs were regulated by cold stress. While, the analyses of targets suggested miR159, miR398 and miR6001 could responses to stress conditions in regulation pathways. Taken together, the results of this study suggest that wheat miRNAs may play important roles in response to abiotic stress.


      PubDate: 2014-04-20T12:37:38Z
       
  • Isolation and characterization of Korean pine (Pinus koraiensis)
           convicilin
    • Abstract: Publication date: July 2014
      Source:Plant Physiology and Biochemistry, Volume 80
      Author(s): Tengchuan Jin , Yang Wang , Yu-Wei Chen , Silvia M. Albillos , Mahendra H. Kothary , Tong-Jen Fu , Boyce Tankersley , Tara H. McHugh , Yu-Zhu Zhang
      A vicilin-like globulin seed storage protein, termed convicilin, was isolated for the first time from Korean pine (Pinus koraiensis). SDS-PAGE analysis revealed that Korean pine convicilin was post-translationally processed. The N-terminal peptide sequences of its components were determined. These peptides could be mapped to a protein translated from an embryo abundant transcript isolated in this study. Similar to vicilin, native convicilin appeared to be homotrimeric. Differential scanning calorimetry (DSC) analyses revealed that this protein is less resistant to thermal treatment than Korean pine vicilin. Its transition temperature was 75.57 °C compared with 84.13 °C for vicilin. The urea induced folding-unfolding equilibrium of pine convicilin monitored by intrinsic fluorescence could be interpreted in terms of a two-state model, with a C m of 4.41 ± 0.15 M.
      Graphical abstract image

      PubDate: 2014-04-20T12:37:38Z
       
  • Expression of peanut Iron Regulated Transporter 1 in tobacco and rice
           plants confers improved iron nutrition
    • Abstract: Publication date: July 2014
      Source:Plant Physiology and Biochemistry, Volume 80
      Author(s): Hongchun Xiong , Xiaotong Guo , Takanori Kobayashi , Yusuke Kakei , Hiromi Nakanishi , Tomoko Nozoye , Lixia Zhang , Hongyun Shen , Wei Qiu , Naoko K. Nishizawa , Yuanmei Zuo
      Iron (Fe) limitation is a widespread agricultural problem in calcareous soils and severely limits crop production. Iron Regulated Transporter 1 (IRT1) is a key component for Fe uptake from the soil in dicot plants. In this study, the peanut (Arachis hypogaea L.) AhIRT1 was introduced into tobacco and rice plants using an Fe-deficiency-inducible artificial promoter. Induced expression of AhIRT1 in tobacco plants resulted in accumulation of Fe in young leaves under Fe deficient conditions. Even under Fe-excess conditions, the Fe concentration was also markedly enhanced, suggesting that the Fe status did not affect the uptake and translocation of Fe by AhIRT1 in the transgenic plants. Most importantly, the transgenic tobacco plants showed improved tolerance to Fe limitation in culture in two types of calcareous soils. Additionally, the induced expression of AhIRT1 in rice plants also resulted in high tolerance to low Fe availability in calcareous soils.


      PubDate: 2014-04-20T12:37:38Z
       
  • The nodule conductance to O2 diffusion increases with phytase activity in
           N2-fixing Phaseolus vulgaris L
    • Abstract: Publication date: July 2014
      Source:Plant Physiology and Biochemistry, Volume 80
      Author(s): Mohamed Lazali , Jean Jacques Drevon
      To understand the relationship between phosphorus use efficiency (PUE) and respiration for symbiotic nitrogen fixation (SNF) in legume nodules, six recombinant inbred lines of common bean (RIL Phaseolus vulgaris L.), contrasting in PUE for SNF, were inoculated with Rhizobium tropici CIAT899, and grown under hydroaeroponic culture with sufficient versus deficient P supply (250 versus 75 μmol P plant−1 week−1). At the flowering stage, the biomass of plants and phytase activity in nodules were analyzed after measuring O2 uptake by nodulated roots. Our results show that the P-deficiency significantly increased the phytase activity in nodules of all RILs though with highest extent for RILs 147, 29 and 83 (ca 45%). This increase in phytase activity was associated with an increase in nodule respiration (ca 22%) and in use of the rhizobial symbiosis (ca 21%). A significant correlation was found under P-deficiency between nodule O2 permeability and phytase activity in nodules for RILs 104, 34 and 115. This observation is to our knowledge the first description of a correlation between O2 permeability and phytase activity of a legume nodule. It is concluded that the variation of phytase activity in nodules can increase the internal utilization of P and might be involved in the regulation of nodule permeability for the respiration linked with SNF and the adaptation to P-deficiency.


      PubDate: 2014-04-15T20:27:48Z
       
  • Expression of flavonoid biosynthesis genes and accumulation of flavonoid
           in wheat leaves in response to drought stress
    • Abstract: Publication date: July 2014
      Source:Plant Physiology and Biochemistry, Volume 80
      Author(s): Dongyun Ma , Dexiang Sun , Chenyang Wang , Yaoguang Li , Tiancai Guo
      Flavonoids are the low molecular weight polyphenolic secondary metabolic compounds, and have various functions in growth, development, reproduction, and stress defense. However, little is known about the roles of the key enzymes in the flavonoids biosynthesis pathway in response to drought stress in winter wheat. Here, we investigated the expression pattern of flavonoids biosynthesis genes and accumulation of flavonoids in wheat leaves under drought stress. Quantitative real-time PCR analysis showed that there were a rapid increase in expression levels of TaCHS, TaCHI, TaF3H, TaFNS, TaFLS, TaDFR, and TaANS under drought stress in two wheat cultivars Aikang 58 (AK) and Chinese Spring (CS). The cultivar CS exhibited higher genes expression levels of TaCHS, TaCHI, TaF3H, TaFLS, TaDFR, and TaANS, and the cultivar AK showed a higher expression level of TaFNS gene during drought treatment. The increase rates of genes expression were superior in AK compared to CS. Total phenolics content, total flavonoids content, anthocyanin content, and schaftoside content in wheat leaves were enhanced during drought treatment and cultivar CS had a relative higher accumulation. These results suggest that the flavonoids pathway genes expression and accumulation of flavonoids compounds may be closely related to drought tolerant in wheat. Further, flavonoids response mechanism may be different between wheat cultivars.


      PubDate: 2014-04-15T20:27:48Z
       
  • Effects of exogenous 24-epibrassinolide on the photosynthetic membranes
           under non-stress conditions
    • Abstract: Publication date: July 2014
      Source:Plant Physiology and Biochemistry, Volume 80
      Author(s): Anelia G. Dobrikova , Radka S. Vladkova , Georgi D. Rashkov , Svetla J. Todinova , Sashka B. Krumova , Emilia L. Apostolova
      In the present work the effects of exogenous 24-epibrassinolide (EBR) on functional and structural characteristics of the thylakoid membranes under non-stress conditions were evaluated 48 h after spraying of pea plants with different concentrations of EBR (0.01, 0.1 and 1.0 mg.L−1). The results show that the application of 0.1 mg.L−1 EBR has the most pronounced effect on the studied characteristics of the photosynthetic membranes. The observed changes in 540 nm light scattering and in the calorimetric transitions suggest alterations in the structural organization of the thylakoid membranes after EBR treatment, which in turn influence the kinetics of oxygen evolution, accelerate the electron transport rate, increase the effective quantum yield of photosystem II and the photochemical quenching. The EBR-induced changes in the photosynthetic membranes are most probably involved in the stress tolerance of plants.


      PubDate: 2014-04-15T20:27:48Z
       
  • Alleviation of salt-induced photosynthesis and growth inhibition by
           salicylic acid involves glycinebetaine and ethylene in mungbean (Vigna
           radiata L.)
    • Abstract: Publication date: July 2014
      Source:Plant Physiology and Biochemistry, Volume 80
      Author(s): M. Iqbal R. Khan , M. Asgher , Nafees A. Khan
      The influence of salicylic acid (SA) in alleviation of salt stress in mungbean (Vigna radiata L.) through modulation of glycinebetaine (GB) and ethylene was studied. SA application at 0.5 mM increased methionine (Met) and GB accumulation in plants concomitant with the suppression of ethylene formation by inhibiting 1-aminocyclopropane carboxylic acid synthase (ACS) activity more conspicuously under salt stress than no stress. The increased GB accumulation together with reduced ethylene under salt stress by SA application was associated with increased glutathione (GSH) content and lower oxidative stress. These positive effects on plant metabolism induced by SA application led to improved photosynthesis and growth under salt stress. These results suggest that SA induces GB accumulation through increased Met and suppresses ethylene formation under salt stress and enhances antioxidant system resulting in alleviation of adverse effects of salt stress on photosynthesis and growth. These effects of SA were substantiated by the findings that application of SA-analogue, 2, 6, dichloro-isonicotinic acid (INA) and ethylene biosynthesis inhibitor, aminoethoxyvinylglycine (AVG) resulted in similar effects on Met, GB, ethylene production, photosynthesis and growth under salt stress. Future studies on the interaction between SA, GB and ethylene could be exploited for adaptive responses of plants under salt stress.


      PubDate: 2014-04-15T20:27:48Z
       
  • Molecular cloning and characterization of a novel adenylyl cyclase gene,
           HpAC1, involved in stress signaling in Hippeastrum x hybridum
    • Abstract: Publication date: July 2014
      Source:Plant Physiology and Biochemistry, Volume 80
      Author(s): Brygida Świeżawska , Krzysztof Jaworski , Agnieszka Pawełek , Weronika Grzegorzewska , Piotr Szewczuk , Adriana Szmidt-Jaworska
      Adenylyl cyclases (ACs) are enzymes that generate cyclic AMP, which is involved in different physiological and developmental processes in a number of organisms. Here, we report the cloning and characterization of a new plant adenylyl cyclases (AC) gene, designated HpAC1, from Hippeastrum x hybridum. This gene encodes a protein of 206 amino acids with a calculated molecular mass of 23 kD and an isoelectric point of 5.07. The predicted amino acid sequence contains all the typical features of and shows high identity with putative plant ACs. The purified, recombinant HpAC1 is able to convert ATP to cAMP. The complementation test that was performed to analyze the ability of HpAC1 to compensate for the AC deficiency in the Escherichia coli SP850 strain revealed that HpAC1 functions as an adenylyl cyclase and produces cyclic AMP. Moreover, it was shown that the transcript level of HpAC1 and cyclic AMP concentration changed during certain stress conditions. Both mechanical damage and Phoma narcissi infection lead to two sharp increases in HpAC1 mRNA levels during a 72-h test cycle. Changes in intracellular cAMP level were also observed. These results may indicate the participation of a cAMP-dependent pathway both in rapid and systemic reactions induced after disruption of symplast and apoplast continuity.


      PubDate: 2014-04-15T20:27:48Z
       
  • Cerium Dioxide and Zinc Oxide Nanoparticles Alter the Nutritional Value of
           Soil Cultivated Soybean Plants
    • Abstract: Publication date: Available online 5 April 2014
      Source:Plant Physiology and Biochemistry
      Author(s): Jose R. Peralta-Videa , Jose A. Hernandez-Viezcas , Lijuan Zhao , Baltazar Corral Diaz , Yuan Ge , John H. Priester , Patricia Ann Holden , Jorge L. Gardea-Torresdey
      The aim of this study was to determine nutrient elements in soybean (Glycine max) plants cultivated in farm soil amended with nCeO2 at 0-1000 mg kg-1 and nZnO at 0-500 mg kg-1. Digested samples were analyzed by ICP-OES/MS. Compared to control, pods from nCeO2 at 1000 mg kg-1 had significantly less Ca but more P and Cu, while pods from 100 mg kg-1 nZnO had more Zn, Mn, and Cu. Plants treated with nZnO showed significant correlations among Zn, P, and S in pods with Zn in roots. Correlations among pod Zn/root Zn was r = 0.808 (p ≤ 0.01) and pod P/root P was r = 0.541 (p ≤ 0.05). The correlation among pod S/root S was r = -0.65 (p ≤ 0.01). While nCeO2 treatments exhibited significant correlations between pod Ca/root Ca (r = 0.645, p ≤ 0.05). The data suggest that nCeO2 and nZnO alter the nutritional value of soybean, which could affect the health of plants, humans, and animals.
      Graphical abstract image

      PubDate: 2014-04-10T23:25:35Z
       
  • Photochemical and biophysical feedbacks of C3 and C4 Mediterranean
           halophytes to atmospheric CO2 enrichment confirmed by their stable isotope
           signatures
    • Abstract: Publication date: July 2014
      Source:Plant Physiology and Biochemistry, Volume 80
      Author(s): B. Duarte , D. Santos , H. Silva , J.C. Marques , I. Caçador
      According the latest predictions, an increase of about two times in atmospheric CO2 concentrations, is expected to occur by the end of this century. In order to understand the effects of this atmospheric composition changes on two abundant Mediterranean halophytes (Halimione portulacoides and Spartina maritima), mesocosmos trials were performed simulating two atmospheric CO2 environments (380 ppm and 760 ppm of CO2 respectively). The two chosen halophyte species present different metabolic characteristics: H. portulacoides, is a C3 specie while S. maritima is a C4 species. Distinct feedbacks were obtained for each of the studied species. Stable Isotope discrimination showed that both species showed an enhancement of the Rubisco carboxylation capacity and photosynthetic efficiency mostly due to an increase in intracellular [CO2]. In H. portulacoides CO2 fertilization induced an enhancement of ETR and a decrease in non-photochemical quenching and in dissipated energy fluxes. On the other hand the C4 grass S. maritima, already at full capacity, showed no photosynthetic enhancement. In fact this highly productive grass presented lower photosynthetic efficiencies accompanied by increases in dissipated energy fluxes mostly due to reductions in energy flux associated with the transport of reducing power throughout the quinone pool. The accumulation of reducing power led to oxidative stress, and thus the photosynthetic ability of this grass was greatly reduced. Both these feedbacks to realistic future CO2 concentrations are important consideration for in future primary productivity models, indicating a possible reduced abundance of the pioneer S. maritima and an increased biomass spreading of the sediment stabilizer H. portulacoides, inevitably affecting the morphology and function of the salt marshes imposed by these atmospheric changes, both in terms of ecosystem functioning and loss of biodiversity.


      PubDate: 2014-04-10T23:25:35Z
       
  • Identification and characterization of the 14-3-3 gene family in Hevea
           brasiliensis
    • Abstract: Publication date: Available online 5 April 2014
      Source:Plant Physiology and Biochemistry
      Author(s): Zi-Ping Yang , Hui-Liang Li , Dong Guo , Xiao Tang , Shi-Qing Peng
      The 14-3-3 proteins are a family of conserved phospho-specific binding proteins involved in diverse physiological processes. Although the genome-wide analysis of this family has been carried out in certain plant species, little is known about 14-3-3 protein genes in rubber tree (Hevea brasiliensis). In this study, we identified 10 14-3-3 protein genes (designated as HbGF14a to HbGF14j) in the latest rubber tree genome. A phylogenetic tree was constructed and found to demonstrate that HbGF14s can be divided into two major groups. Tissue-specific expression profiles showed that 10 HbGF14 were expressed in at least one of the tissues, which suggested that HbGF14s participated in numerous cellular processes. The 10 HbGF14s responded to jasmonic acid (JA) and ethylene (ET) treatment, which suggested that these HbGF14s were involved in response to JA and ET signaling. The target of HbGF14c protein was related to small rubber particle protein, a major rubber particle protein that is involved in rubber biosynthesis. These findings suggested that 14-3-3 proteins may be involved in the regulation of natural rubber biosynthesis.


      PubDate: 2014-04-10T23:25:35Z
       
  • The constitutive expression of a two transgene construct enhances the
           abiotic stress tolerance of chrysanthemum
    • Abstract: Publication date: Available online 5 April 2014
      Source:Plant Physiology and Biochemistry
      Author(s): Aiping Song , Juan An , Zhiyong Guan , Jiafu Jiang , Fadi Chen , Wanghuai Lou , Weimin Fang , Zhaolei Liu , Sumei Chen
      Various abiotic stresses downgrade the quality and productivity of chrysanthemum. A construct carrying both CcSOS1 (from Chrysanthemum crassum) and CdICE1 (from C. dichrum) was constitutively expressed in the chrysanthemum variety ‘Jinba’. The transgenic plants were superior to the wild type (WT) ones with respect to their sensitivity to low temperature, drought and salinity, as measured by visible damage and plant survival. Salinity stressed transgenic plants accumulated more proline, and their level of superoxide dismutase and peroxidase activity was higher than in WT plants. At the physiological level, they suffered less loss of viable leaf area, maintained a lower leaf electrolyte conductivity and retained more chlorophyll (a+b). The ratio between the K+ and Na+ content was higher in the root, stem and median leaves of salinity stressed transgenic plants than in those of WT plants.


      PubDate: 2014-04-10T23:25:35Z
       
  • Comparison of oxidative stress in four Tillandsia species exposed to
           cadmium
    • Abstract: Publication date: July 2014
      Source:Plant Physiology and Biochemistry, Volume 80
      Author(s): Jozef Kováčik , Petr Babula , Bořivoj Klejdus , Josef Hedbavny
      This is first study comparing four morphologically variable species of the genus Tillandsia and therefore various responses to the cadmium (Cd) action were expected. In accordance, Cd accumulation increased in order Tillandsia fasciculata < Tillandsia brachycaulos < Tillandsia pruinosa < Tillandsia capillaris, reaching 29.6 and 197.4 μg g−1 DW in first and last species after watering with 2 μM Cd2+ solution over 30 days. Fluorescence visualization of oxidative stress confirmed increase in ROS and especially elevation in hydroperoxides though no visible symptoms appeared on the plants. At the same time, nitric oxide generation and nitroso-glutathione depletion by Cd treatment were typically observed. Fluorescence staining of Cd using two dyes (PhenGreen and Leadmium) showed that Leadmium fits better with AAS quantification. Macro- and micro-nutrients were not considerably affected except for zinc. Reduced glutathione content was the highest in control T. fasciculata while oxidized glutathione in T. capillaris. Ascorbic acid amount revealed extreme quantitative differences among species and decreased in T. fasciculata only. Free amino acids accumulation was similar among species except for T. capillaris and Cd caused both depletion and increase but without high quantitative differences. Data are explanatively discussed in the context of limited literature related to oxidative stress in epiphytic plants and with general responses of plants to cadmium/heavy metals.


      PubDate: 2014-04-10T23:25:35Z
       
  • Influence of crop load on the expression patterns of starch metabolism
           genes in alternate-bearing Citrus trees
    • Abstract: Publication date: Available online 5 April 2014
      Source:Plant Physiology and Biochemistry
      Author(s): Sergio G. Nebauer , Begoña Renau-Morata , Yolanda Lluch , Edurne Baroja-Fernández , Javier Pozueta-Romero , Rosa-Victoria Molina
      The fruit is the main sink organ in Citrus and captures almost all available photoassimilates during its development. Consequently, carbohydrate partitioning and starch content depend on the crop load of Citrus trees. Nevertheless, little is known about the mechanisms controlling the starch metabolism at the tree level in relation to presence of fruit. The aim of this study was to find the relation between the seasonal variation of expression and activity of the genes involved in carbon metabolism and the partition and allocation of carbohydrates in ‘Salustiana’ sweet orange trees with different crop loads. Metabolisable carbohydrates, and the expression and activity of the enzymes involved in sucrose and starch metabolism, including sucrose transport, were determined during the year in the roots and leaves of 40-year-old trees bearing heavy crop loads (‘on’ trees) and trees with almost no fruits (‘off’ trees). Fruit altered photoassimilate partitioning in trees. Sucrose content tended to be constant in roots and leaves, and surplus fixed carbon is channeled to starch production. Differences between ‘on’ and ‘off’ trees in starch content can be explained by differences in ADP-glucose pyrophosphorylase (AGPP) expression/activity and α-amylase activity which varies depending on crop load. The observed relation of AGPP and UGPP (UDP-glucose pyrophosphorylase) is noteworthy and indicates a direct link between sucrose and starch synthesis. Furthermore, different roles for sucrose transporter SUT1 and SUT2 have been proposed. Variation in soluble sugars content cannot explain the differences in gene expression between the ‘on’ and ‘off’ trees. A still unknown signal from fruit should be responsible for this control.


      PubDate: 2014-04-10T23:25:35Z
       
  • A transcriptional approach to unravel the connection between
           phospholipases A2 and D and ABA signal in citrus under water stress
    • Abstract: Publication date: July 2014
      Source:Plant Physiology and Biochemistry, Volume 80
      Author(s): Paco Romero , M. Teresa Lafuente , Fernando Alférez
      The effect of water stress on the interplay between phospholipases (PL) A2 and D and ABA signalling was investigated in fruit and leaves from the sweet orange Navelate and its fruit-specific ABA-deficient mutant Pinalate by studying simultaneously expression of 5 PLD and 3 PLA2-encoding genes. In general, expression levels of PLD-encoding genes were higher at harvest in the flavedo (coloured outer part of the peel) from Pinalate. Moreover, a higher and transient increase in expression of CsPLDα, CsPLDβ, CsPLDδ and CsPLDζ was observed in the mutant as compared to Navelate fruit under water stress, which may reflect a mechanism of acclimation to water stress influenced by ABA deficiency. An early induction in CsPLDγ gene expression, when increase in peel damage during fruit storage was most evident, suggested a role for this gene in membrane degradation processes during water stress. Exogenous ABA on mutant fruit modified the expression of all PLD genes and reduced the expression of CsPLDα and CsPLDβ by 1 week to levels similar to those of Navelate, suggesting a repressor role of ABA on these genes. In general, CssPLA 2 α and β transcript levels were lower in flavedo from Pinalate than from Navelate fruit during the first 3 weeks of storage, suggesting that expression of these genes also depends at least partially on ABA levels. Patterns of expression of PLD and PLA2-encoding genes were very similar in Navelate and Pinalate leaves, which have similar ABA levels, when comparing both RH conditions. Results comparison with other from previous works in the same experimental systems helped to decipher the effect of the stress severity on the differential response of some of these genes under dehydration conditions and pointed out the interplay between PLA2 and PLD families and their connection with ABA signalling in citrus.


      PubDate: 2014-04-10T23:25:35Z
       
  • Activity levels and expression of antioxidant enzymes in the
           ascorbate–glutathione cycle in artificially aged rice seed
    • Abstract: Publication date: July 2014
      Source:Plant Physiology and Biochemistry, Volume 80
      Author(s): Guangkun Yin , Xia Xin , Chao Song , Xiaoling Chen , Jinmei Zhang , Shuhua Wu , Ruifang Li , Xu Liu , Xinxiong Lu
      Reactive oxygen species are the main contributors to seed deterioration. In order to study scavenging systems for reactive oxygen species in aged seed, we performed analyses using western blotting, real-time quantitative reverse-transcription polymerase chain reaction, high-performance liquid chromatography, and antioxidant enzyme activity analyses in artificially aged rice seeds (Oryza sativa L. cv. wanhua no.11). Aging seeds by storing them at 50 °C for 1, 9, or 17 months increased the superoxide radical and hydrogen peroxide levels and reduced the germination percentage from 99% to 92%, 55%, and 2%, respectively. The activity levels of superoxide dismutase (SOD), glutathione reductase (GR), and dehydroascorbate reductase (DHAR) did not change in aged seeds. In contrast, the activity levels of catalase (CAT), ascorbate peroxidase (APX), and monodehydroascorbate reductase (MDHAR) were significantly decreased in aged seeds, as were the expression of catalase and cytosolic ascorbate peroxidase protein. Transcript accumulation analysis showed that specific expression patterns were complex for each of the antioxidant enzyme types in the rice embryos. Overall, the expression of most genes was down-regulated, along with their protein expression. In addition, the reduction in the amount of ascorbate and glutathione was associated with the reduction in scavenging enzymes activity in aged rice embryos. Our data suggest that the depression of the antioxidant system, especially the reduction in the expression of CAT1, APX1 and MDHAR1, may be responsible for the accumulation of reactive oxygen species in artificially aged seed embryos, leading to a loss of seed vigor.


      PubDate: 2014-04-05T19:15:34Z
       
 
 
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