Plant, Cell & Environment

Cover image for Vol. 37 Issue 9

Early View (Online Version of Record published before inclusion in an issue)

Edited By: Keith Mott

Impact Factor: 5.906

ISI Journal Citation Reports © Ranking: 2013: 10/196 (Plant Sciences)

Online ISSN: 1365-3040

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  2. 101 - 108
  1. Reviews

    1. You have free access to this content
      Utilizing intraspecific variation in phenotypic plasticity to bolster agricultural and forest productivity under climate change

      MICHAEL J. ASPINWALL, MICHAEL E. LOIK, VICTOR RESCO DE DIOS, MARK G. TJOELKER, PAXTON R. PAYTON and DAVID T. TISSUE

      Article first published online: 1 SEP 2014 | DOI: 10.1111/pce.12424

      Information gathered from genotype-by-environment interactions (G × E), which demonstrate intraspecific variation in phenotypic plasticity, may prove important for bolstering agricultural and forest productivity under climate change. We conceptualize the importance of intraspecific variation in phenotypic plasticity in the context of agriculture and forestry, and discuss the physiological and genetic factors influencing plasticity differences among genotypes. Our assessment reveals the need for an integrated understanding of the mechanisms of G × E, and more extensive assessments of intraspecific variation in agricultural and forest species responses to climate change under field conditions.

  2. Original Articles

    1. You have full text access to this OnlineOpen article
      Identification and functional characterization of the Arabidopsis Snf1-related protein kinase SnRK2.4 phosphatidic acid-binding domain

      MAGDALENA M. JULKOWSKA, FIONN MCLOUGHLIN, CARLOS S. GALVAN-AMPUDIA, JOHANNA M. RANKENBERG, DOROTA KAWA, MARIA KLIMECKA, MICHEL A. HARING, TEUN MUNNIK, EDGAR E. KOOIJMAN and CHRISTA TESTERINK

      Article first published online: 1 SEP 2014 | DOI: 10.1111/pce.12421

      This study characterizes the effect of phosphatidic acid (PA) on the cellular localization of a protein kinase that is important for maintaining root growth in saline conditions; SnRK2.4. Membrane affinity and PA-specificity of SnrK2.4 was shown and a primary PA-binding site was identified. PA binding is not sufficient for salt-induced re-localization, but requires additional domains in the protein. Overexpression of the PA-binding domain resulted in reduced root growth, possibly by competing for available PA.

  3. Reviews

    1. Responses of tree species to heat waves and extreme heat events

      ROBERT TESKEY, TIMOTHY WERTIN, INGVAR BAUWERAERTS, MAARTEN AMEYE, MARY ANNE MCGUIRE and KATHY STEPPE

      Article first published online: 1 SEP 2014 | DOI: 10.1111/pce.12417

      The number and intensity of heat waves has increased in recent decades and this trend is likely to continue throughout the 21st Century. This review summarizes our current understanding of how extreme heat events affect tree functions from the cellular to the whole plant scale. When drought stress accompanies heat waves, heat stress is exacerbated and can lead to tree mortality. Although there have been only few studies to date, there is evidence of within-species genetic variation that could be exploited to increase heat stress resistance in trees. Understanding the mechanisms of tree responses to extreme temperature events may be critically important for understanding how tree species will be affected by climate change.

  4. Original Articles

    1. Peroxisomal APX knockdown triggers antioxidant mechanisms favourable for coping with high photorespiratory H2O2 induced by CAT deficiency in rice

      RACHEL H. V. SOUSA, FABRICIO E. L. CARVALHO, CAROL W. RIBEIRO, GISELE PASSAIA, JULIANA R. CUNHA, YUGO LIMA-MELO, MÁRCIA MARGIS-PINHEIRO and JOAQUIM A. G. SILVEIRA

      Article first published online: 29 AUG 2014 | DOI: 10.1111/pce.12409

      1. 1. 
        The peroxisomal APX encoded protein has an unknown role in plants;
      2. 2. 
        Peroxisomal APX silenced rice plants were more acclimated to high photorespiration under catalase deficiency;
      3. 3. 
        The physiological acclimation displayed by peroxisomal APX may involve signaling by peroxisomal H2O2, which minimized the photorespiration.
    2. Virus-induced gene silencing reveals control of reactive oxygen species accumulation and salt tolerance in tomato by γ-aminobutyric acid metabolic pathway

      HEXIGEDULENG BAO, XIANYANG CHEN, SULIAN LV, PING JIANG, JUANJUAN FENG, PENGXIANG FAN, LINGLING NIE and YINXIN LI

      Article first published online: 27 AUG 2014 | DOI: 10.1111/pce.12419

      γ-Aminobutyric acid (GABA) accumulates in many plant species in response to environmental stress, but the physiological function of GABA or its metabolic pathway (GABA shunt) in plants remains largely unclear. In the present study, based on loss-of-function studies, our findings revealed the functional involvement of GABA shunt in the salt tolerance of tomato and the putative roles for GABA-related metabolites (such as succinate and γ-hydroxybutyrate) in these processes. These results open exciting perspectives for further investigations of GABA shunt and associated metabolic pathways to the stress adaptation of plants, pointing to these pathways as potential targets for engineering of plant stress tolerance. To our knowledge, this work represents one of the most thorough studies demonstrating the roles of GABA metabolic pathway in defense against environmental stress.

    3. AtMyb7, a subgroup 4 R2R3 Myb, negatively regulates ABA-induced inhibition of seed germination by blocking the expression of the bZIP transcription factor ABI5

      JUN HYEOK KIM, WOO YOUNG HYUN, HOAI NGUYEN NGUYEN, CHAN YOUNG JEONG, LIMING XIONG, SUK-WHAN HONG and HOJOUNG LEE

      Article first published online: 27 AUG 2014 | DOI: 10.1111/pce.12415

      Various Myb proteins have been shown to perform crucial roles in plants, including primary and secondary metabolism, regulation of cell fate and identity, regulation of development, and in the responses to biotic and abiotic stresses. Although 126 R2R3 Myb proteins (with 2 Myb repeats) have been found in Arabidopsis, a full understanding of the function of most of these proteins is lacking. We used molecular biological and genetic analyses to characterize the function of AtMyb7. qRT-PCR was used to determine the levels of stress response gene transcripts in wild-type and atmyb7 plants. We found that Arabidopsis AtMyb7 plays a critical role in seed germination. atmyb7 showed a lower germination rate than wild-type under high salt and abscisic acid (ABA) stress conditions. Furthermore, AtMyb7 pro-GUS seeds showed different expression patterns in response to variations in the seed imbibition period. AtMyb7 negatively controls the expression of the gene encoding the bZIP transcription factor ABI5, which is a key transcription factor in ABA signaling and serves as a crucial regulator of germination inhibition in Arabidopsis.

    4. Jasmonic acid signalling mediates resistance of the wild tobacco Nicotiana attenuata to its native Fusarium, but not Alternaria, fungal pathogens

      VAN THI LUU, STEFAN SCHUCK, SANG-GYU KIM, ARNE WEINHOLD and IAN T. BALDWIN

      Article first published online: 27 AUG 2014 | DOI: 10.1111/pce.12416

      Our study examines the phytohormone-mediated signaling responses of the wild tobacco plant to its native fungal pathogens and provides insights into the dynamics of pathogen attack in a natural environment. Three native fungal pathogen species of F usarium and A lternaria induce different salicylic and jasmonic acid responses in their wild tobacco host plant, which results in disease symptoms characteristic for each pathogen. By using transgenic lines, the trade-offs between JA- and SA- mediated defense responses was analyzed in a situation in which plants were under attack from hemi-biotrophic F usarium species (SA-mediated response) and necrotrophic A lternaria species (JA-mediated response).

    5. High light decreases xylem contribution to fruit growth in tomato

      JOCHEN HANSSENS, TOM DE SWAEF and KATHY STEPPE

      Article first published online: 27 AUG 2014 | DOI: 10.1111/pce.12411

      Recent contradicting evidence on the contribution of xylem and phloem to fruit growth in tomato urges the need for a better understanding of the mechanisms involved in fruit growth, and how these are affected by environmental factors. In this manuscript we demonstrate that decreasing light intensity by shading significantly increased the relative xylem contribution to tomato fruit growth. Plants growing under low light intensity were able to maintain a stronger water potential gradient between stem and fruits, thereby promoting xylem influx. Being able to manipulate contributions of xylem and phloem by changing light intensity is important to further improve fruit quality.

    6. ZmCPK1, a calcium-independent kinase member of the Zea mays CDPK gene family, functions as a negative regulator in cold stress signalling

      PHILIPP WECKWERTH, BRITTA EHLERT and TINA ROMEIS

      Article first published online: 22 AUG 2014 | DOI: 10.1111/pce.12414

      Our manuscript extends the characterization of the maize CDPK gene family by the identification of so far undescribed isoforms as well as by compiling all existing information about this gene family (Table I). Two CDPK isoforms, ZmCPK1 and ZmCPK25, were functionally described in the maize cold stress response where Zmcpk1 gene expression is up-regulated by cold exposure while Zmcpk25 is repressed. Upon ectopic expression of the biochemical active, but not of kinase-deficient, ZmCPK1 protein cold-inducible marker gene Zmerf3 is repressed. Consistent with a role as negative regulator of the plant cold stress response transgenic ZmCPK1 Arabidopsis display altered acclimation-induced freezing tolerance. Biochemical analysis reveals low but constitutive and calcium-independent protein kinase activity for ZmCPK1. Our data identify ZmCPK1 as a negative regulator of the maize cold stress response whose function is controlled on transcriptional level rather than by post-translational modification through calcium binding.

    7. Involvement of chlororespiration in chilling stress in the tropical species Spathiphyllum wallisii

      MARÍA V. SEGURA and MARÍA J. QUILES

      Article first published online: 22 AUG 2014 | DOI: 10.1111/pce.12406

      The present paper provides new data on the up-regulation, in response to chilling stress under high illumination, of the two enzymes of chlororespiration (the chloroplast NDH complex and the plastid terminal oxidase) and the PGR5 polypeptide, an essential component of the photosynthetic cyclic electron flow sensitive to antimycin A, in a plant species of tropical origin.

  5. Editorial

    1. Plant tolerance of flooding stress – recent advances

      JULIA BAILEY-SERRES and TIMOTHY D. COLMER

      Article first published online: 21 AUG 2014 | DOI: 10.1111/pce.12420

  6. Commentary

  7. Original Articles

    1. Linking oxygen availability with membrane potential maintenance and K+ retention of barley roots: implications for waterlogging stress tolerance

      FANRONG ZENG, DENNIS KONNERUP, LANA SHABALA, MEIXUE ZHOU, TIMOTHY DAVID COLMER, GUOPING ZHANG and SERGEY SHABALA

      Article first published online: 18 AUG 2014 | DOI: 10.1111/pce.12422

      This work used barley varieties contrasting in waterlogging tolerance to investigate a causal relationship between changes in intracellular potassium homeostasis, membrane potential measurements, and oxygen transport from the shoot. Intact roots were capable of maintaining H+-pumping activity under hypoxic conditions while disrupting O2 transport from shoot to root resulted in more pronounced membrane depolarization under O2-limited conditions and a rapid loss of the cell viability. It is concluded that the ability of root cells to maintain MP and cytosolic K+ homeostasis is central to plant performance under waterlogging, and efficient O2 transport from the shoot may enable operation of the plasma membrane H+-ATPase in roots even under conditions of severe O2 limitation in the soil solution.

  8. Reviews

    1. Role of aquaporins in determining transpiration and photosynthesis in water-stressed plants: crop water-use efficiency, growth and yield

      MENACHEM MOSHELION, OFER HALPERIN, RONY WALLACH, RAM OREN and DANIELLE A. WAY

      Article first published online: 16 AUG 2014 | DOI: 10.1111/pce.12410

      Here we review the role of vascular, mesophyll and tonoplast AQPs in regulating the plant isohydric threshold. The tissue specific and cell specific activity of AQPs in controlling the membrane water and/or CO2 permeability is discussed as a tool to increase yield under both normal and water-stressed conditions.

  9. Original Articles

    1. Diel growth patterns of young soybean (Glycine max) leaflets are synchronous throughout different positions on a plant

      MICHAEL FRIEDLI and ACHIM WALTER

      Article first published online: 16 AUG 2014 | DOI: 10.1111/pce.12407

      In this study, we investigated diel leaf growth from the primary leaves to leaflets of the seventh trifoliate leaf of soybean (Glycine max) on the same plants with a recently developed imaging-based method. All leaflets displayed a consistent diel growth pattern with maximum growth towards the end of the night. Therefore, the diel growth pattern of any leaf at a given point in time is representative for the overall diel growth pattern of the plant leaf canopy and a deviation from the normal diel growth pattern can indicate that the plant is currently facing stress.

    2. Coordination between water transport capacity, biomass growth, metabolic scaling and species stature in co-occurring shrub and tree species

      DUNCAN D. SMITH and JOHN S. SPERRY

      Article first published online: 13 AUG 2014 | DOI: 10.1111/pce.12408

      We tested the often assumed but little tested idea that increasing whole plant sapflow or hydraulic conductance leads to greater biomass growth. We compared co-occurring shrub and tree species and generally found intraspecific isometry linking hydraulic conductance, sapflow and growth, although the two functional groups differed with trees tending to exhibit lower sapflow yet greater growth for a given hydraulic conductance. Additionally, relative growth rate tended to decline with size in all species but more steeply so in shrubs, apparently owing to subtle size-dependent changes in WUE instead of limitation by water transport. A model based on xylem anatomy predicted hydraulic conductances and suggested that species employ ontogenetic changes in branching architecture to achieve observed hydraulic scaling.

  10. Reviews

    1. Threats to xylem hydraulic function of trees under ‘new climate normal’ conditions

      MACIEJ A. ZWIENIECKI and FRANCESCA SECCHI

      Article first published online: 13 AUG 2014 | DOI: 10.1111/pce.12412

      Many structural and functional tree properties evolved to protect xylem from embolism and loss of transport function or to restore xylem transport capacity following embolism formation. Challenges to transport systems occur during events of extreme environmental conditions and these are predicted to increase in frequency and intensity under ‘the new climate normal’ conditions. We review here the current state of knowledge describing principles of embolism formation and plant recovery from water stress to provide insight into future challenges that woody plants will face and guidance to research directions aimed at mitigation of climate change impacts on woody plants in natural and agricultural tree communities.

  11. Original Articles

    1. Epidermal UV-A absorbance and whole-leaf flavonoid composition in pea respond more to solar blue light than to solar UV radiation

      SARI M. SIIPOLA, TITTA KOTILAINEN, NINA SIPARI, LUIS O. MORALES, ANDERS V. LINDFORS, T. MATTHEW ROBSON and PEDRO J. APHALO

      Article first published online: 13 AUG 2014 | DOI: 10.1111/pce.12403

      We studied the relative importance of the UV and blue wavebands of sunlight for the phenolics in leaves of pea (Pisum sativum cv. Meteor) plants grown outdoors. We report a large reduction in epidermal flavonoids and a change in the flavonoid composition in leaf extracts when solar blue light was attenuated. Under the conditions of our experiment, these effects of blue light attenuation were much larger than those caused by attenuation of UV radiation.

  12. Commentary

  13. Original Articles

    1. Diffusional limitations explain the lower photosynthetic capacity of ferns as compared with angiosperms in a common garden study

      M. CARRIQUÍ, H. M. CABRERA, M. À. CONESA, R. E. COOPMAN, C. DOUTHE, J. GAGO, A. GALLÉ, J. GALMÉS, M. RIBAS-CARBO, M. TOMÁS and J. FLEXAS

      Article first published online: 13 AUG 2014 | DOI: 10.1111/pce.12402

      No previous studies simultaneously compared the photosynthetic functioning of ferns and angiosperms in a common garden.

      The photosynthetic rate of ferns was about half that of angiosperms, being stomatal and mesophyll conductances co-responsible for the lower photosynthesis.

      The photosynthesis in ferns was mainly constrained by g m, being cell wall thickness and the surface of chloroplasts exposed to intercellular air spaces the most related anatomical traits.

    2. Mesophyll conductance decreases in the wild type but not in an ABA-deficient mutant (aba1) of Nicotiana plumbaginifolia under drought conditions

      YUSUKE MIZOKAMI, KO NOGUCHI, MIKIKO KOJIMA, HITOSHI SAKAKIBARA and ICHIRO TERASHIMA

      Article first published online: 13 AUG 2014 | DOI: 10.1111/pce.12394

      This study aimed at investigating the possible involvement of ABA in decreasing mesophyll conductance under drought conditions. Here, we used the ABA deficient mutant of Nicotiana plumbaginifolia, aba1, and photosynthetic characteristics of this mutant and the wild type were compared. The experiments provided the clear evidence that the increase in leaf ABA decreased mesophyll conductance.

    3. How does solar ultraviolet-B radiation improve drought tolerance of silver birch (Betula pendula Roth.) seedlings?

      T. MATTHEW ROBSON, SAARA M. HARTIKAINEN and PEDRO J. APHALO

      Article first published online: 13 AUG 2014 | DOI: 10.1111/pce.12405

      We hypothesized that solar ultraviolet (UV) radiation would protect silver birch seedlings from the detrimental effects of water stress. Plants were grown under nine combinations of solar UV treatments and water deficit conditions. In seedlings under water deficit, UV attenuation reduced growth compared with seedlings receiving the full spectrum of solar radiation; whereas the growth and morphology of well-watered seedlings was largely unaffected by UV attenuation. There was an interactive effect of the treatment combination on water relations, which was more apparent as a change in the water potential at which leaves wilted or plants died than through differences in gas exchange.

    4. You have full text access to this OnlineOpen article
      Differential expression of miRNAs and their target genes in senescing leaves and siliques: insights from deep sequencing of small RNAs and cleaved target RNAs

      SHAWN R. THATCHER, SHAUL BURD, CHRISTOPHER WRIGHT, AMNON LERS and PAMELA J. GREEN

      Article first published online: 13 AUG 2014 | DOI: 10.1111/pce.12393

      To address the limited knowledge of small RNAs from senescing A rabidopsis on a global scale, we deeply sequenced these molecules from senescing leaves and siliques. Several nutrient-responsive miRNAs and their targets were found to be regulated in opposite directions in leaves and siliques as senescence progressed, which is consistent with these miRNAs playing a role in nutrient remobilization. Additionally, a new senescence-inducible small RNA locus was discovered and shown to target some mRNAs of the alpha tubulin family, which were reduced as senescence progressed. Overall this work implicates small RNAs in the both nutrient remobilization and cellular structure changes that take place during senescence.

    5. In comparison with nitrate nutrition, ammonium nutrition increases growth of the frostbite1Arabidopsis mutant

      ANNA PODGÓRSKA, MONIKA OSTASZEWSKA, PER GARDESTRÖM, ALLAN G. RASMUSSON and BOŻENA SZAL

      Article first published online: 13 AUG 2014 | DOI: 10.1111/pce.12404

      In this paper, we analysed the redox metabolism of frostbite1 (fro1) plants lacking Complex I under ammonium nutrition. We showed that, although ammonium leads to stress in wild type plants, ammonium does not cause reductive stress in fro1 plants. Our experimental and bioinformatic analyses indicated that mtETC dysfunction strongly influences apoplastic reactive oxygen species content and pH, and suggested that the faster growth of fro1 plants under ammonium nutrition probably results from modification of the cell wall.

    6. Phloem flow and sugar transport in Ricinus communis L. is inhibited under anoxic conditions of shoot or roots

      ANDREAS D. PEUKE, ARTHUR GESSLER, SUSAN TRUMBORE, CAREL W. WINDT, NATALIA HOMAN, EDO GERKEMA and HENK VAN AS

      Article first published online: 8 AUG 2014 | DOI: 10.1111/pce.12399

      In order to test the hypothesis that anoxic conditions should hamper the transport in the phloem, we chose to subject the entire shoot (source) and the entire root (sink) of castor bean plants to anoxia, while monitoring non-invasively phloem transport by means of MRI-flowmetry. Moreover we analyzed carbon compounds in source and sink tissues as well as in phloem saps. Both anoxia treatments reduced sugar transport, however, flow velocity stayed constant, even though sugar concentration in phloem saps changed. Our study overcomes the important shortcomings of recent studies as we provide direct information on the phloem transport, its change due to anoxia and the effect of such change on root carbohydrate supply.

    7. Hormonal dynamics contributes to divergence in seasonal stomatal behaviour in a monsoonal plant community

      SCOTT A.M. MCADAM and TIMOTHY J. BRODRIBB

      Article first published online: 6 AUG 2014 | DOI: 10.1111/pce.12398

      Here we test the hypothesis that species specific biosynthesis, metabolism and stomatal sensitivity to ABA can direct contrasting stomatal behaviours among coexisting species in a natural setting. In the natural community we studied four highly-divergent strategies of water use were associated with different patterns of ABA sensing, synthesis and metabolism by the leaf. These findings provide a novel avenue for future stomatal and phytohormone research through the characterisation of ecological strategies regulated by ABA and stomatal behaviour.

    8. The auxin response factor, OsARF19, controls rice leaf angles through positively regulating OsGH3-5 and OsBRI1

      SAINA ZHANG, SUIKANG WANG, YANXIA XU, CHENLIANG YU, CHENJIA SHEN, QIAN QIAN, MARKUS GEISLER, DE AN JIANG and YANHUA QI

      Article first published online: 6 AUG 2014 | DOI: 10.1111/pce.12397

      Our work revealed that the transcription factor, OsARF19, acts in bridging the molecular network of auxin and BR signaling in rice. OsARF19 functions as a regulator of auxin and BR signalling driving transcription of its downstream genes, including OsGH3-5 and OsBRI1. This novel finding provides important information in our understanding of monocot leaf angle architecture and therefore might be useful to rational close planting of crop plants.

  14. Reviews

    1. Prospects of engineering thermotolerance in crops through modulation of heat stress transcription factor and heat shock protein networks

      SOTIRIOS FRAGKOSTEFANAKIS, SASCHA RÖTH, ENRICO SCHLEIFF and KLAUS-DIETER SCHARF

      Article first published online: 6 AUG 2014 | DOI: 10.1111/pce.12396

      The review compiles recent studies on model and crop plants which suggest that genetic engineering of Hsf-chaperone networks can improve thermotolerance. Although conserved in their basic functions, species-specific variations in the composition and interaction of the two central networks involved in regulation of stress response and maintenance of protein homeostasis under stressful but also normal growth conditions have been described. Hence, manipulations on the molecular level guided only by model plant-specific knowledge transfer might cause unexpected pleiotropic effects. Detailed knowledge of the multi-level regulatory mechanisms controlling the availability and activity of Hsf-chaperone networks undoubtedly is required to unravel promising targets for manipulation and selection of cultivars that can combine both high productivity and enhanced thermotolerance.

  15. Original Articles

    1. Glycosyltransferase-like protein ABI8/ELD1/KOB1 promotes Arabidopsis hypocotyl elongation through regulating cellulose biosynthesis

      XIN WANG, YANJUN JING, BAOCAI ZHANG, YIHUA ZHOU and RONGCHENG LIN

      Article first published online: 5 AUG 2014 | DOI: 10.1111/pce.12395

      This study elucidates a molecular mechanism on how light regulates cellulose synthesis and hypocotyl elongation during plant photomorphogenic growth. The authors demonstrate that ABI8 is a negative regulator of light-inhibition of hypocotyl growth and that HY5 transcription factor directly represses ABI8 expression. ABI8 are down-regulated by light both at the transcription and post-translational levels.

    2. Anion channel SLAH3 functions in nitrate-dependent alleviation of ammonium toxicity in Arabidopsis

      XIAOJIANG ZHENG, KAI HE, THOMAS KLEIST, FANG CHEN and SHENG LUAN

      Article first published online: 26 JUL 2014 | DOI: 10.1111/pce.12389

      Ammonium toxicity in plants has been a long standing problem for crop production. Yet the molecular mechanism remains unknown. This study describes evidence that soil acidification by ammonium is responsible for root growth inhibition and a nitrate channel plays a critical role in alleviating ammonium toxicity in Arabidopsis.

    3. Acclimation to UV-B radiation and visible light in Lactuca sativa involves up-regulation of photosynthetic performance and orchestration of metabolome-wide responses

      J. J. WARGENT, B. C. W. NELSON, T. K. MCGHIE and P. W. BARNES

      Article first published online: 22 JUL 2014 | DOI: 10.1111/pce.12392

      UV-B radiation is often viewed as a source of stress for higher plants. Here, acclimation to UV-B and visible light conditions in Lactuca sativa was explored using a combination of approaches, including gas exchange measurements and metabolic profiling using LC-QTOF-HRMS. We show that acclimation to UV-B involves co-protection from the effects of visible light, and responses to UV-B radiation at a photosynthetic level may not be consistently viewed as damaging to plant development.

    4. PHYTOALEXIN DEFICIENT4 affects reactive oxygen species metabolism, cell wall and wood properties in hybrid aspen (Populus tremula L. × tremuloides)

      IRENEUSZ ŚLESAK, MAGDALENA SZECHYŃSKA-HEBDA, HALINA FEDAK, NATALIA SIDORUK, JOANNA DĄBROWSKA-BRONK, DAMIAN WITOŃ, ANNA RUSACZONEK, ANDRZEJ ANTCZAK, MICHAŁ DROŻDŻEK, BARBARA KARPIŃSKA and STANISŁAW KARPIŃSKI

      Article first published online: 22 JUL 2014 | DOI: 10.1111/pce.12388

      The PHYTOALEXIN DEFICIENT 4 (PAD4) gene is well-known positive regulator of the cell death in Arabidopsis and its function is important in control of integrated abiotic and biotic stress responses. But its function in woody plants is not known. Therefore, we selected transgenic hybrid aspen with reduced or suppressed PAD4 poplar ortholog expression. Our field study demonstrated that the P. tremula x tremuloides PAD gene might be a negative regulator of the cell death and is involved in the regulation of the cellular ROS signalling homeostasis, wood development and cell wall properties.

    5. X-ray microtomography (micro-CT): a reference technology for high-resolution quantification of xylem embolism in trees

      H. COCHARD, S. DELZON and E. BADEL

      Article first published online: 18 JUL 2014 | DOI: 10.1111/pce.12391

      There is ongoing debate over the validity of the techniques used to measure xylem vulnerability. X-ray microtomography (micro-CT) is proposed here as a reference technique as it enables direct visualizations of xylem embolism. These direct visualizations clearly show that xylem conduits are highly resistant to cavitation, which means embolism is unlikely to form and refill on a daily basis.

    6. Comparison of the response to phosphorus deficiency in two lupin species, Lupinus albus and L. angustifolius, with contrasting root morphology

      SACHIKO FUNAYAMA-NOGUCHI, KO NOGUCHI and ICHIRO TERASHIMA

      Article first published online: 18 JUL 2014 | DOI: 10.1111/pce.12390

      We investigated the difference of strategies for phosphorus (P) acquisition in white lupin ( L upinus albus) and narrow leaf lupin ( L . angustifolius) in reference to carbon cost. In response to P deficiency, L . albus produced cluster roots, while L . angustifolius increased biomass allocation to roots. The construction cost was highest in cluster roots in L . albus, and lowest in L . angustifolius roots. Our results shows that under P-deficiency, L . albus produces high-cost cluster roots to increase the P-availability, while L . angustifolius produces large quantities of low-cost roots to enhance the P-uptake.

  16. Commentary

  17. Original Articles

    1. Expression of Arabidopsis acyl-CoA-binding proteins AtACBP1 and AtACBP4 confers Pb(II) accumulation in Brassica juncea roots

      ZHI-YAN DU, MO-XIAN CHEN, QIN-FANG CHEN, JI-DONG GU and MEE-LEN CHYE

      Article first published online: 17 JUL 2014 | DOI: 10.1111/pce.12382

      Arabidopsis acyl-CoA-binding proteins, AtACBP1 and AtACBP4, have been shown to bind lead [Pb(II)] in vitro, prompting us to investigate their potential in Pb(II) phytoremediation. Our results showed that AtACBP1 and AtACBP4 were induced by Pb(II) and putative elements responsive to Pb(II) were identified in the 5′-flanking region of AtACBP1 . Transgenic Arabidopsis overexpressing AtACBP1 sequestered Pb(II) in the trichomes and displayed tolerance to hydrogen peroxide (H 2 O 2) treatment, whereas transgenic Brassica juncea overexpressing AtACBP1 or AtACBP4 sequestered Pb(II) in the cytosol of root tips and vascular tissues, and displayed Pb(II) accumulation in roots. In addition, AtACBP1 and AtACBP4 were induced by H 2 O 2 in roots of wild-type Arabidopsis and transgenic B. juncea overexpressing AtACBP1 or AtACBP4 were protected against Pb(II)-induced lipid peroxidation.

    2. Carbon isotope compositions (δ13C) of leaf, wood and holocellulose differ among genotypes of poplar and between previous land uses in a short-rotation biomass plantation

      M. S. VERLINDEN, R. FICHOT, L. S. BROECKX, B. VANHOLME, W. BOERJAN and R. CEULEMANS

      Article first published online: 12 JUL 2014 | DOI: 10.1111/pce.12383

      The carbon isotope composition (δ13 C) is often used as a proxy for water use efficiency (WUE). For six poplar (Populus) genotypes in a short-rotation (bio-energy) plantation the values of δ13Cwood and δ13Cholocellulose were tightly and positively correlated, but the offset varied significantly among genotypes. The positive relationships between δ13 Cleaf and leaf N suggested that spatial variations in WUE over the plantation were mainly driven by an N-related effect on photosynthetic capacities. As WUE remained largely uncoupled from growth, there is potential to identify poplar genotypes with satisfactory growth and higher WUE.

    3. PtrBAM1, a β-amylase-coding gene of Poncirus trifoliata, is a CBF regulon member with function in cold tolerance by modulating soluble sugar levels

      TING PENG, XIAOFANG ZHU, NIAN DUAN and JI-HONG LIU

      Article first published online: 9 JUL 2014 | DOI: 10.1111/pce.12384

      β-Amylase (BAM) catalyzes starch breakdown to generate maltose, but the role of BAM genes in cold tolerance remains still poorly understood. PtrBAM1 , a chloroplast-localizing BAM gene of P oncirus trifoliata, was induced by abiotic stresses and played a positive role in starch degradation. Overexpression of PtrBAM1 in tobacco conferred enhanced tolerance to cold stresses at chilling and freezing temperature, accompanied by lower accumulation of ROS. The promoter of PtrBAM1 was shown to be recognized by CBF, suggesting that PtrBAM1 may act as a member of CBF regulon.

    4. Identification of primary and secondary metabolites with phosphorus status-dependent abundance in Arabidopsis, and of the transcription factor PHR1 as a major regulator of metabolic changes during phosphorus limitation

      BIKRAM-DATT PANT, POOJA PANT, ALEXANDER ERBAN, DAVID HUHMAN, JOACHIM KOPKA and WOLF-RÜDIGER SCHEIBLE

      Article first published online: 4 JUL 2014 | DOI: 10.1111/pce.12378

      Unlike transcript data, large-scale metabolite data for P-limited plants are still missing. Current metabolite profiling technologies were used to determine the abundance of nearly 350 primary and secondary metabolites in roots and shoots of P-limited and P-replete Arabidopsis wildtype plants and mutants in P-signaling. Besides determining a large number of metabolites with P-status dependent abundance, the transcription factor PHR1 was found to be important for metabolic reprogramming during P-limitation.

    5. Relationship between starch degradation and carbon demand for maintenance and growth in Arabidopsis thaliana in different irradiance and temperature regimes

      SARAH M. PILKINGTON, BEATRICE ENCKE, NICOLE KROHN, MELANIE HÖHNE, MARK STITT and EVA-THERESA PYL

      Article first published online: 4 JUL 2014 | DOI: 10.1111/pce.12381

      The impact of demand on the rate of starch breakdown was compared in source- and sink-limited Arabidopsis plants. In source-limited plants the rate of starch breakdown is paced by the clock such that starch is almost but not completely exhausted at dawn, and is not increased above this rate to meet demand, even when starch reserves are so low that they do not cover the requirements for maintenance and catabolism is induced early in the night. In sink-limited plants, which do not completely mobilise their starch during the night, starch degradation is accelerated to meet the increased demand for maintenance and growth. The rate of growth at night is closely linked to the rate of starch breakdown, while maintenance respiration is largely independent of starch breakdown except in conditions when carbon reserves are very low.

    6. Heme-heme oxygenase 1 system is involved in ammonium tolerance by regulating antioxidant defence in Oryza sativa

      YANJIE XIE, YU MAO, SHENG XU, HENG ZHOU, XINGLIANG DUAN, WEITI CUI, JING ZHANG and GUOHUA XU

      Article first published online: 4 JUL 2014 | DOI: 10.1111/pce.12380

      The molecular mechanism of heme-heme oxygenase1 (heme-HO1) in the regulation of ammonium tolerance is still lacking. Our results showed that rice OsSE5 expression was up-regulated by NH4Cl. Oxidative stress and subsequent growth inhibition induced by excess NH4Cl was partly mitigated by pretreatment with hemin (HO1 inducer) or carbon monoxide (CO, a by-product of HO1 activity), or intensified by zinc protoporphyrin (ZnPP, a potent inhibitor of HO1 activity). Combined with pharmacological, genetic, and molecular analyses, we proposed that heme-HO1 system was involved in the regulation of NH4+ tolerance by manipulation of downstream antioxidant defence in rice and Arabidopsis.

  18. Commentaries

  19. Original Articles

    1. Inverse modulation of the energy sensor Snf1-related protein kinase 1 on hypoxia adaptation and salt stress tolerance in Arabidopsis thaliana

      JONG HEE IM, YOUNG-HEE CHO, GEUN-DON KIM, GEUN-HO KANG, JUNG-WOO HONG and SANG-DONG YOO

      Article first published online: 30 JUN 2014 | DOI: 10.1111/pce.12375

      Terrestrial plants face a dual abiotic stress of salt and hypoxia when seawater floods fields. A hypoxia-inducible energy sensor snf1-related protein kinase1 directly modulates protein stability of salt/ABA-inducible AtMYC2 and suppresses AtMYC2-dependent gene induction that eventually compromises plant stress tolerance under high-salt seawater. From the study, we learned how terrestrial plants may have hard time to colonize tidal mud flats with the regular seawater flooding.

    2. You have full text access to this OnlineOpen article
      Gibberellin biosynthesis and signal transduction is essential for internode elongation in deepwater rice

      MADOKA AYANO, TAKAHIRO KANI, MIKIKO KOJIMA, HITOSHI SAKAKIBARA, TAKUYA KITAOKA, TAKESHI KUROHA, ROSALYN B. ANGELES-SHIM, HIDEMI KITANO, KEISUKE NAGAI and MOTOYUKI ASHIKARI

      Article first published online: 24 JUN 2014 | DOI: 10.1111/pce.12377

      Deepwater rice obtained the ability for rapid internode elongation to avoid drowning and adapt to flooded condition. How does it regulate internode elongation? Using both physiological and genetic approach, this paper shows that the plant hormone, gibberellin (GA) regulates internode elongation.

    3. How changing root system architecture can help tackle a reduction in soil phosphate (P) levels for better plant P acquisition

      J. HEPPELL, P. TALBOYS, S. PAYVANDI, K. C. ZYGALAKIS, J. FLIEGE, P. J. A. WITHERS, D. L. JONES and T. ROOSE

      Article first published online: 24 JUN 2014 | DOI: 10.1111/pce.12376

      A collaboration between Southampton and Bangor University address how the alteration of root system architecture could (by breeding or genetic manipulation) produce greater P uptake. Experimental results of wheat roots are measured, from lengths and widths, including root hairs and a phosphate uptake profile. The data is used in conjunction with a mathematical model, which can simulate new root systems and the effects they have on P uptake. Due to the readily available global rock phosphate (P) reserves running out within the next 50-130 years, this work is of importance in assessing how crops will cope in soils with a reduced P concentration. We would be delighted if this paper was published in Plant, Cell & Environment, to further advance the P shortage awareness and potential solutions for its inevitable arrival.

  20. Reviews

    1. Re-interpreting plant morphological responses to UV-B radiation

      T. MATTHEW ROBSON, KAREL KLEM, OTMAR URBAN and MARCEL A. K. JANSEN

      Article first published online: 24 JUN 2014 | DOI: 10.1111/pce.12374

      We review the effects of UV-B on plant morphology, using the improved mechanistic understanding of UV perception and signalling following elucidation of the UVR8 photoreceptor to reappraise published results. Despite a substantially improved understanding of molecular, cellular and organismal UV-B responses, there remains a clear gap in our knowledge of the interactions between these organisational levels, their function in UV-protection, and consequences for plant fitness and plant-plant interactions. Future research will need to disentangle the seemingly contradictory interactions and substantial diversity in reported phenotypes that occur at the threshold UV dose where regulation and stress-induced morphogenesis overlap.

  21. Original Articles

    1. Investigating patterns of symbiotic nitrogen fixation during vegetation change from grassland to woodland using fine scale δ15N measurements

      FIONA M. SOPER, THOMAS W. BOUTTON and JED P. SPARKS

      Article first published online: 24 JUN 2014 | DOI: 10.1111/pce.12373

      Natural abundance foliar δ15N is often used to infer rates of nitrogen fixation in woody plants in natural ecosystems. We expanded δ15N sampling to include soil solution and xylem sap, and demonstrated variation in internal fractionation between species that can substantially affect interpretation of N fixation. In addition, we identified short- and long-term temporal variability in isotopic composition of soil solution and magnitude of soil-xylem fractionation that could be used to investigate seasonal and successional N cycling and fixation dynamics. Expansion of sampling along the N uptake pathway reveals processes obscured by foliar sampling alone.

    2. Induced carbon reallocation and compensatory growth as root herbivore tolerance mechanisms

      CHRISTELLE A. M. ROBERT, RICHARD A. FERRIERI, STEFANIE SCHIRMER, BENJAMIN A. BABST, MICHAEL J. SCHUELLER, RICARDO A. R. MACHADO, CARLA C. M. ARCE, BRUCE E. HIBBARD, JONATHAN GERSHENZON, TED C. J. TURLINGS and MATTHIAS ERB

      Article first published online: 22 JUN 2014 | DOI: 10.1111/pce.12359

      Upon attack by leaf herbivores, many plants reallocate photoassimilates below ground. However, little is known about how plants respond when the roots themselves come under attack. By using radioactive 11CO2, we demonstrate that maize plants that are attacked by the root feeding larvae of the western corn rootworm allocate more carbon to the stems and less to the roots, an effect which is associated with a marked thickening of the stems and increased growth of stem-borne crown roots. These result indicate that induced carbon reallocation may help maize plants to tolerate root herbivore attack.

    3. The contributions of apoplastic, symplastic and gas phase pathways for water transport outside the bundle sheath in leaves

      THOMAS N. BUCKLEY

      Article first published online: 16 JUN 2014 | DOI: 10.1111/pce.12372

      The pathways for water movement outside the xylem are poorly known. This study derived an analytical framework to compute conductances of apoplastic, symplastic and gas phase pathways for horizontal and vertical water transport outside the bundle sheath from measurable anatomical and biophysical parameters. The results suggest most conductance outside the bundle sheath is apoplastic, but that gas phase transport can play a similarly large role in vertical water movement when large temperature gradients exist between the center of the leaf and the epidermis.

    4. Is nitrogen transfer among plants enhanced by contrasting nutrient-acquisition strategies?

      FRANÇOIS P. TESTE, ERIK J. VENEKLAAS, KINGSLEY W. DIXON and HANS LAMBERS

      Article first published online: 10 JUN 2014 | DOI: 10.1111/pce.12367

      The main aim of this study was to investigate N transfer between non-N2-fixing plants of different nutrient-acquisition strategies. Nutrient sharing may represent a mechanism for aggregating more plant species into an area than predicted under competition theory. In plant communities when N and P are co-limiting, liberal movement of N between plants could promote equalising effects between species. Therefore, nutrient exchanges may play a fundamental ecological role in promoting plant coexistence in ecosystems under new climatic and anthropogenic pressures with outstanding relevance to restoration of biodiverse plant communities.

    5. Identification of quantitative trait loci and a candidate locus for freezing tolerance in controlled and outdoor environments in the overwintering crucifer Boechera stricta

      JAE-YUN HEO, DONGSHENG FENG, XIAOMU NIU, THOMAS MITCHELL-OLDS, PETER H. VAN TIENDEREN, DWIGHT TOMES and M. ERIC SCHRANZ

      Article first published online: 9 JUN 2014 | DOI: 10.1111/pce.12365

      Development of freezing tolerance can be affected by photoperiod, temperature and photosynthetic performance; however, there has been limited research on the interaction of these factors. We evaluated recombinant inbred lines of an Arabidopsis relative, Boechera stricta, under controlled Long-Day (LD), Short-Day (SD) and in an Outdoor Environment (OE). Our results revealed significant variation for chilling and freezing tolerance and photosynthetic performance in different environments. We found only three main-effect QTL: one only in controlled SD, one in both controlled SD and LD and one in all three conditions that was particularly predictive for the Outdoor Experiment and was syntenic to the CBF loci.

    6. An insight into the sensitivity of maize to photoperiod changes under controlled conditions

      QIANG CHEN, HAO ZHONG, XIAN-WEI FAN and YOU-ZHI LI

      Article first published online: 9 JUN 2014 | DOI: 10.1111/pce.12361

      • Failure in development of tassels at V9 stage under long photoperiod (LP) is an early indicator for judging photoperiod sensitivity.
      • Photoperiod changes could make a marked impact on spatial layout of maize inflorescence.
      • The adaptation of temperate-adapted maize lines to LP is due to the better coordination of expression among photoperiod-sensing genes instead of the loss of the genes.
      • High photoperiod sensitivity of maize is due to high expression of circadian rhythm-responding genes improperly early in the light.
    7. Reactive oxygen species, abscisic acid and ethylene interact to regulate sunflower seed germination

      HAYAT EL-MAAROUF-BOUTEAU, YASAR SAJJAD, JéRéMIE BAZIN, NICOLAS LANGLADE, SIMONA M. CRISTESCU, SANDRINE BALZERGUE, EMMANUEL BAUDOUIN and CHRISTOPHE BAILLY

      Article first published online: 5 JUN 2014 | DOI: 10.1111/pce.12371

      This work investigates the relationship between reactive oxygen species (ROS), abscisic acid (ABA) and ethylene in the regulation of sunflower seed germination and it deciphers the molecular basis of the effects of ROS on seed germination. We show that ROS, provided by methylviologen to the dormant sunflower seeds, and ethylene act synergistically to promote germination whereas ROS and ABA have antagonistic effects. Microarrays analyses allowed identifying molecular players of ROS signaling and they show that ROS transcriptionally repress ABA signaling pathways but that they stimulate the expression of genes related to redox and calcium signaling for stimulating germination. Our work allows proposing ROS as a central hub in the regulation of seed germination.

    8. Soybean resistance to stink bugs (Nezara viridula and Piezodorus guildinii) increases with exposure to solar UV-B radiation and correlates with isoflavonoid content in pods under field conditions

      JORGE A. ZAVALA, CARLOS A. MAZZA, FRANCISCO M. DILLON, HUGO D. CHLUDIL and CARLOS L. BALLARÉ

      Article first published online: 5 JUN 2014 | DOI: 10.1111/pce.12368

      High doses of UV-B radiation can have damaging effects of plants; however, ambient levels of UV-B radiation often have beneficial effects, promoting plant immunity against pests and pathogens. In this paper we show that ambient UV-B radiation increased the accumulation of the isoflavonoids daidzin and genistin in pods of field-grown soybean crops. Soybean crops grown under attenuated UV-B were more attacked by stink bugs and had higher numbers of damaged seeds than crops grown under ambient UV-B radiation. Our results suggest that constitutive or UV-B-induced isoflavonoids increase soybean resistance to stink bugs under field conditions.

  22. Reviews

    1. Protein phosphatases PP2A, PP4 and PP6: mediators and regulators in development and responses to environmental cues

      CATHRINE LILLO, AMR R. A. KATAYA, BEHZAD HEIDARI, MARIA T. CREIGHTON, DUGASSA NEMIE-FEYISSA, ZEKARIAS GINBOT and ELSE M. JONASSEN

      Article first published online: 5 JUN 2014 | DOI: 10.1111/pce.12364

      This review presents the current status of knowledge on protein phosphatase 2A (PP2A), PP4 and PP6 in plants with special attention to regulation of physiological processes. Involvement of PP2A and PP6 in hormone signalling, development, and responses to environmental stresses are described. Since these protein phosphatases are highly conserved in eukaryotes, comparisons are made between Arabidopsis thaliana, Homo sapiens and Saccharomyces cerevisia, and point to putative regulatory PP4 subunits in Arabidopsis not yet investigated, as well as well as some conserved regulatory functions of PP2A, PP6 and PP4 in yeast and mammals not yet explored in plants.

  23. Original Articles

    1. The Medicago truncatula hypermycorrhizal B9 mutant displays an altered response to phosphate and is more susceptible to Aphanomyces euteiches

      HOAI-NAM TRUONG, ELISE THALINEAU, LAURENT BONNEAU, CARINE FOURNIER, SOPHIE POTIN, SANDRINE BALZERGUE, DIEDERIK VAN TUINEN, SYLVAIN JEANDROZ and DOMINIQUE MORANDI

      Article first published online: 2 JUN 2014 | DOI: 10.1111/pce.12370

      We have characterized the response to phosphate of the hypermycorrhizal mutant B9 of Medicago truncatula. We show through physiological approaches, root architecture analyses and transcriptomics that this mutant displays an altered response to phosphate. We propose that the hypermycorrhizal phenotype of the B9 mutant is linked to its Pi-limited status favoring AM symbiosis. In addition this mutant is more susceptible to the oomycete Aphanomyces euteiches, suggesting possible links between symbiosis, pathogenesis and response to phosphate.

    2. Potato plants ectopically expressing Arabidopsis thalianaCBF3 exhibit enhanced tolerance to high-temperature stress

      HAIOU DOU, KUNPENG XV, QINGWEI MENG, GANG LI and XINGHONG YANG

      Article first published online: 2 JUN 2014 | DOI: 10.1111/pce.12366

      In this study, we found that transformation of tomato plants with the AtCBF3 gene enhanced tolerance to high temperatures. AtCBF3 improved the capacities of photosynthesis and antioxidant defense by regulating the expression of genes involved in these functions, and this enhanced tolerance might not depend on the regulatory pathways in which HSP70 is involved. The expression of AtCBF3 was induced by high temperature possibly through the regulatory pathways that Ca2+ participates in.

    3. A reassessment of the role of sucrose synthase in the hypoxic sucrose-ethanol transition in Arabidopsis

      ANTONIETTA SANTANIELLO, ELENA LORETI, SILVIA GONZALI, GIACOMO NOVI and PIERDOMENICO PERATA

      Article first published online: 2 JUN 2014 | DOI: 10.1111/pce.12363

      Anaerobic metabolism requires continuous fuelling of carbon units, also provided from sucrose.

      The anaerobic catabolism of sucrose under hypoxia is thought to require the activity of sucrose synthase, being this enzymatic reaction more energetically favorable than that of invertase.

      In Arabidopsis, the requirement of the low-oxygen induced sucrose synthase isoforms for ethanol production was evident only under conditions of limiting sugar availability, although partly compensated by invertase activities.

      We conclude that, contrary to general belief, the sucrose synthase pathway is not the preferential route for sucrose metabolism under hypoxia in Arabidopsis.

    4. A cell type-specific view on the translation of mRNAs from ROS-responsive genes upon paraquat treatment of Arabidopsis thaliana leaves

      MARIA BENINA, DIMAS MENDES RIBEIRO, TSANKO S. GECHEV, BERND MUELLER-ROEBER and JOS H. M. SCHIPPERS

      Article first published online: 2 JUN 2014 | DOI: 10.1111/pce.12355

      The study illustrates the response of different Arabidopsis thaliana leaf cells and tissues to oxidative stress at the translational level, an aspect of reactive oxygen species (ROS) biology that has been little studied in the past. Our data reveal insights into how translational regulation of ROS-responsive genes is fine-tuned at the cellular level, a phenomenon contributing to the integrated physiological response of leaves to stresses involving changes in ROS levels.

    5. You have full text access to this OnlineOpen article
      Tissue-specific and light-dependent regulation of phytochrome gene expression in rice

      AKIKO BABA-KASAI, NAHO HARA and MAKOTO TAKANO

      Article first published online: 2 JUN 2014 | DOI: 10.1111/pce.12354

      In order to characterize the tissue-specific expression of PHYTOCHROME genes in rice, we examined the expression patterns of rice PHYTOCHROME promoter- GUS fusion genes. The results demonstrated PHYA expression was restricted to vascular bundles in light-grown seedlings as a result of light-mediated down-regulation of the PHYA gene in the other tissues and that the repression of PHYA is mediated by phyB signals in a tissue-specific manner.

    6. Physiological characterization and genetic modifiers of aberrant root thigmomorphogenesis in mutants of Arabidopsis thalianaMILDEW LOCUS O genes

      PRZEMYSLAW BIDZINSKI, SANDRA NOIR, SHERMINEH SHAHI, ANJA REINSTÄDLER, DOMINIKA MARTA GRATKOWSKA and RALPH PANSTRUGA

      Article first published online: 2 JUN 2014 | DOI: 10.1111/pce.12353

      We examined the aberrant root thigmotropism phenotype of Arabidopsis thaliana mlo4 and mlo11 mutants, which is represented by tight root spirals, using a range of physiological assays and by genetic means. The characteristic root curls are not recapitulated in a set of tested mutants with abnormal root growth patterns. We found that the formation of the spirals is pH-dependent, affected by exogenous calcium levels, modulated by microtubule structure and suppressed by mutants with defective auxin transport and gravitropism.

    7. Hydrogen peroxide mediates abscisic acid-induced HSP70 accumulation and heat tolerance in grafted cucumber plants

      HAO LI, SHAN-SHAN LIU, CHANG-YU YI, FENG WANG, JIE ZHOU, XIAO-JIAN XIA, KAI SHI, YAN-HONG ZHOU and JING-QUAN YU

      Article first published online: 28 MAY 2014 | DOI: 10.1111/pce.12360

      This study showed that grafting to the luffa rootstock, a heat tolerant cucurbit species, can result in an enhanced tolerance to heat stress in cucumber leaves. The enhanced tolerance was attributed to an ABA-dependent H2O2-driven mechanism in a rootstock-induced systemic response to heat involved in the root-shoot communication.

    8. The acclimation of photosynthesis and respiration to temperature in the C3–C4 intermediate Salsola divaricata: induction of high respiratory CO2 release under low temperature

      ANTHONY GANDIN, NURIA K. KOTEYEVA, ELENA V. VOZNESENSKAYA, GERALD E. EDWARDS and ASAPH B. COUSINS

      Article first published online: 26 MAY 2014 | DOI: 10.1111/pce.12345

      Photosynthesis in C3-C4 intermediates reduces carbon loss by photorespiration through refixing photorespired CO2 within bundle sheath cells. This is beneficial under warm temperatures where rates of photorespiration are high; however, it is unknown how photosynthesis in C3-C4 plants acclimates to growth under cold conditions. Therefore, the cold tolerance of the C3-C4 Salsola divaricata was tested to determine whether it reverts to C3 photosynthesis when grown under low temperatures. Plants were grown under cold (15/10 °C), moderate (25/18 °C) or hot (35/25 °C) day/night temperatures and analyzed to determine how photosynthesis, respiration and C3-C4 features acclimate to these growth conditions. The CO2 compensation point and net rates of CO2 assimilation in cold grown plants changed dramatically when measured in response to temperature. However, this was not due to the loss of C3-C4 intermediacy but rather to a large increase in mitochondrial respiration supported primarily by the alternative non-phosphorylating oxidative pathway (AOP), and to a lesser degree the cytochrome oxidative pathway. The increase in respiration and AOP capacity in cold grown plants likely protects against reactive oxygen species in mitochondria and photodamage in chloroplasts by consuming excess reductant via the alternative mitochondrial respiratory electron transport chain.

    9. Magnesium availability regulates the development of root hairs in Arabidopsis thaliana (L.) Heynh

      YAOFANG NIU, RUSHAN CHAI, LIJUAN LIU, GULEI JIN, MIAO LIU, CAIXIAN TANG and YONGSONG ZHANG

      Article first published online: 23 MAY 2014 | DOI: 10.1111/pce.12362

      Root hairs are reported to be plastic in response to nutrient supply, but relatively little is known about their development in response to magnesium (Mg) availability. This study demonstrated a profound effect of Mg supply on the development of root hairs in Arabidopsis, through the characterized Ca2+ and ROS signals that modulate the elongation of root hairs and the expression of root-hair morphogenetic genes. It opens up the opportunity of understanding on how plant root development in response to Mg availability and provides an alternative route of identifying genes responsible for sensing and signaling Mg nutrient limitations or excess.

    10. Chilling to zero degrees disrupts pollen formation but not meiotic microtubule arrays in Triticum aestivum L.

      DEBORAH A. BARTON, LAURENCE C. CANTRILL, ANDREW M. K. LAW, COLLIN G. PHILLIPS, BRUCE G. SUTTON and ROBYN L. OVERALL

      Article first published online: 22 MAY 2014 | DOI: 10.1111/pce.12358

      In the field, spring wheat in Australia may experience extended periods of night time chilling during flower development. Prolonged cold treatment under controlled conditions was shown to induce pollen sterility and reduce yield substantially. The effect of seven consecutive nights of chilling on anther and pollen development (microsporogenesis) revealed that increased plasmolysis, cytomixis and death of developing pollen cells were associated with increased sterility. Microtubules, which are temperature sensitive, were unaffected by chilling treatments during meiosis.

    11. You have full text access to this OnlineOpen article
      Four Arabidopsis AREB/ABF transcription factors function predominantly in gene expression downstream of SnRK2 kinases in abscisic acid signalling in response to osmotic stress

      TAKUYA YOSHIDA, YASUNARI FUJITA, KYONOSHIN MARUYAMA, JUNRO MOGAMI, DAISUKE TODAKA, KAZUO SHINOZAKI and KAZUKO YAMAGUCHI-SHINOZAKI

      Article first published online: 22 MAY 2014 | DOI: 10.1111/pce.12351

      Abscisic acid (ABA) plays important roles in osmotic stress-responsive gene expression mainly through three bZIP transcription factors, AREB1, AREB2, and ABF3, which are activated by SnRK2s such as SRK2D, SRK2E, and SRK2I (SRK2D/E/I). However, transcription factors other than the three AREB/ABFs that function downstream of SRK2D/E/I remain obscure. Here, we report that ABF1 is a functional homolog of AREB1, AREB2, and ABF3 in ABA-dependent gene expression from a comparative analysis between the areb1 areb2 abf3 abf1 and areb1 areb2 abf3 mutants. Moreover, genome-wide transcriptome analyses revealed that expression of downstream genes of SRK2D/E/I were mostly impaired in the areb1 areb2 abf3 abf1 quadruple mutant, suggesting that the four AREB/ABFs are the predominant transcription factors downstream of SRK2D/E/I in ABA signaling in response to osmotic stress.

    12. From UVR8 to flavonol synthase: UV-B-induced gene expression in Sauvignon blanc grape berry

      LINLIN LIU, SCOTT GREGAN, CHRIS WINEFIELD and BRIAN JORDAN

      Article first published online: 22 MAY 2014 | DOI: 10.1111/pce.12349

      This research investigates the effect of development and UV-B on flavonols and the regulation of gene activity in Vitis vinifera L. var. Sauvignon blanc grapes. Results suggest flavonol biosynthesis and gene activity are stimulated by UV-B and the low fluence UV-B pathway is a major determinant of this response. There is also a strong influence of development on gene expression. This is the first research to analyse signal transduction associated with the recently discovered UV-B photoreceptor UVR8 and makes a substantial contribution to understanding UV-B responses in an important commercial species.

    13. UV-B mediated metabolic rearrangements in poplar revealed by non-targeted metabolomics

      MORITZ KALING, BASEM KANAWATI, ANDREA GHIRARDO, ANDREAS ALBERT, JANA BARBRO WINKLER, WERNER HELLER, CSENGELE BARTA, FRANCESCO LORETO, PHILIPPE SCHMITT-KOPPLIN and JÖRG-PETER SCHNITZLER

      Article first published online: 19 MAY 2014 | DOI: 10.1111/pce.12348

      This work demonstrates the physiological and metabolic adjustments of isoprene emitting and non-emitting poplars made in response to first time UV-B exposure. Therefore we used poplars grown in the absence of UV radiation to a 20-leaf-stem-stage and then exposed them to high UV-B radiation for two weeks in our sun simulators. Combining non-targeted metabolomics with gas exchange analysis and confocal microscopy we aimed understanding how UV-B radiation triggers metabolome-wide changes, affects isoprene emission, photosynthetic performance, epidermal light attenuation and finally how isoprene-free poplars adjust their metabolome under UV-B radiation.

    14. Is stomatal conductance optimized over both time and space in plant crowns? A field test in grapevine (Vitis vinifera)

      THOMAS N. BUCKLEY, SEBASTIA MARTORELL, ANTONIO DIAZ-ESPEJO, MAGDALENA TOMÀS and HIPÓLITO MEDRANO

      Article first published online: 15 MAY 2014 | DOI: 10.1111/pce.12343

      Carbon gain is maximised for a given total transpiration rate if the marginal carbon product of water is invariant in time and space, provided the curvature of the relationship between net CO2 assimilation rate and transpiration rate. We tested the spatial dimension of this prediction, as well as the requirement for negative curvature, for the first time, in 14 positions across four grapevine canopies over one day. We found substantial systematic deviations between the observed and optimal spatial patterns of water loss, and we also found that positive curvature occurred in 40% of leaves, largely due to low boundary layer conductance. Our results highlight the importance of diffusive resistances other than stomatal in the economics of carbon-water balance, and they suggest that optimisation theory may need to be revised to account for the economic significance of differences among crown positions in hydraulic limitations to transpiration rate.

    15. Mesophyll cells of C4 plants have fewer chloroplasts than those of closely related C3 plants

      MATT STATA, TAMMY L. SAGE, TROY D. RENNIE, ROXANA KHOSHRAVESH, STEFANIE SULTMANIS, YANNAY KHAIKIN, MARTHA LUDWIG and ROWAN F. SAGE

      Article first published online: 14 MAY 2014 | DOI: 10.1111/pce.12331

      To enhance CO 2 diffusion to the site of carboxylation in the chloroplasts, C 3 plants have high numbers of chloroplasts which cover much of the mesophyll cell periphery. In C 4 plants, by contrast, the first carboxylation step occurs in the mesophyll cytosol where PEP carboxylase is located. Here, we show that C 4 plants from 12 lineages of C 4 evolution have approximately half the number of chloroplasts per mesophyll cell as their close C 3 relatives, and half the chloroplast coverage of the mesophyll cell perimeter. This may reflect altered selection pressure to optimize diffusion to the cytoplasmic site of carboxylation in C 4 plants.

    16. You have full text access to this OnlineOpen article
      Effects of elevated [CO2] on maize defence against mycotoxigenic Fusarium verticillioides

      MARTHA M. VAUGHAN, ALISA HUFFAKER, ERIC A. SCHMELZ, NICOLE J. DAFOE, SHAWN CHRISTENSEN, JAMES SIMS, VITOR F. MARTINS, JAY SWERBILOW, MARITZA ROMERO, HANS T. ALBORN, LEON HARTWELL ALLEN and PETER E. A. TEAL

      Article first published online: 13 MAY 2014 | DOI: 10.1111/pce.12337

      Elevated [CO2] increases maize susceptibility to Fusarium verticillioides proliferation but mycotoxin levels are unaltered. The attenuation of maize 13-LOXs and JA production correlates with reduced terpenoid phytoalexins and increased susceptibility. Furthermore, the attenuated induction of 9-LOXs, which have been suggested to stimulate mycotoxin biosynthesis, is consistent with reduced fumonisin per unit fungal biomass at elevated [CO2].

    17. Emission of herbivore elicitor-induced sesquiterpenes is regulated by stomatal aperture in maize (Zea mays) seedlings

      I. SEIDL-ADAMS, A. RICHTER, K. B. BOOMER, N. YOSHINAGA, J. DEGENHARDT and J. H. TUMLINSON

      Article first published online: 13 MAY 2014 | DOI: 10.1111/pce.12347

      The importance of volatile organic compounds in plant defense against insect herbivores and pathogens is widely recognized, but the mechanisms by which they are synthesized and released are not yet fully understood. Our detailed time course data on gene transcript levels, as well as emitted and in-planta accumulated sesquiterpene levels during light and dark periods, force the conclusion that, in maize, stomata guard cells play a critical role in regulating sesquiterpene emission. This suggests that reduction in the number and size of stomata, whether due to climate change or development of drought resistant varieties, may reduce amounts of emitted volatiles. As a result, these plants would be more vulnerable to insect herbivory, due to reduced capability to recruit natural enemies of the attacking herbivore.

    18. Deciphering the molecular bases for drought tolerance in Arabidopsis autotetraploids

      JUAN C. DEL POZO and ELENA RAMIREZ-PARRA

      Article first published online: 11 MAY 2014 | DOI: 10.1111/pce.12344

      Entire-genome duplication (autopolyploidy) is a common phenomenon in many plant species and often leads to better adaptation to environmental conditions. However, we lack information about the physiological, cellular and molecular mechanisms that explain better adaptation to different stresses in autotetraploid plants. Our work indicates that, in Arabidopsis thaliana, tetraploidy promotes alterations in cell proliferation and organ size in a tissue-dependent manner. Furthermore, this is the first report showing that autotetraploid Arabidopsis increased drought tolerance by altering stomatal activity, ABA signaling and ROS homeostasis. In addition, transcriptomic data shed light on the molecular basis associated with stress tolerance in polyploid plants, that includes hormonal regulation and redox processes.

  24. Reviews

    1. Membrane transporters mediating root signalling and adaptive responses to oxygen deprivation and soil flooding

      SERGEY SHABALA, LANA SHABALA, JUAN BARCELO and CHARLOTTE POSCHENRIEDER

      Article first published online: 11 MAY 2014 | DOI: 10.1111/pce.12339

      Over 17 million km2 of land is affected by soil flooding every year, making crop breeding for flooding tolerance one of the imperatives. This review argues that targeting plasma- and organelle-based membrane transporters may be instrumental in achieving this goal. The molecular identity of key membrane transporters mediating plant adaptive responses to oxygen deprivation and soil toxins is revealed, and the modes of their regulation are discussed. It is concluded that the progress in the field may be achieved by pyramiding physiological traits that confer efficient energy maintenance, cytosolic ion homeostasis, and ROS control and detoxification.

  25. Original Articles

    1. UV-B and temperature enhancement affect spring and autumn phenology in Populus tremula

      C. B. STRØMME, R. JULKUNEN-TIITTO, U. KRISHNA, A. LAVOLA, J. E. OLSEN and L. NYBAKKEN

      Article first published online: 11 MAY 2014 | DOI: 10.1111/pce.12338

      As light quality is recognised to affect phenological shifts in several perennial plant species, Ultraviolet B (UV-B) has not yet, to our knowledge, been shown to affect any such processes. In our study, increased UV-B radiation significantly affected phenological shifts in the dioecious tree species P opulus tremula. Furthermore, we found different responsiveness to treatments between sexes. UV-B and temperature enhancement treatments were applied in the field during autumn, and male plants displayed earlier bud set in autumn and bud break in spring following UV-B enhancement.

    2. You have full text access to this OnlineOpen article
      Global reprogramming of transcription and metabolism in Medicago truncatula during progressive drought and after rewatering

      JI-YI ZHANG, MARIA H. CRUZ DE CARVALHO, IVONE TORRES-JEREZ, YUN KANG, STACY N. ALLEN, DAVID V. HUHMAN, YUHONG TANG, JEREMY MURRAY, LLOYD W. SUMNER and MICHAEL K. UDVARDI

      Article first published online: 11 MAY 2014 | DOI: 10.1111/pce.12328

      Global transcriptional and metabolic responses to drought and rewatering were investigated in Medicago truncatula, a naturally drought-adapted model legume species. Integration of metabolomic and transcriptomic data yielded insights into the regulation of metabolic pathways underlying drought-stress adaptation. Many genes and metabolites with expression tightly coupled to drought intensity were identified, suggesting active involvement in Medicago drought resistance. These could prove useful targets for future translational approaches to improve closely related crop plants such as common bean, soybean and pea.

    3. Developmental stage specificity of transcriptional, biochemical and CO2 efflux responses of leaf dark respiration to growth of Arabidopsis thaliana at elevated [CO2]

      R. J. CODY MARKELZ, LAUREN N. VOSSELLER and ANDREW D. B. LEAKEY

      Article first published online: 11 MAY 2014 | DOI: 10.1111/pce.12323

      Plant respiration responses to elevated growth [CO 2] are key uncertainties in predicting future crop and ecosystem function. Growth at elevated [CO 2] was found to stimulate dark respiration only after leaves transitioned from carbon sinks into carbon sources. This finding has implications for modeling of future plant function and identifying targets for further investigation of the molecular and biochemical mechanisms regulating metabolism in response to global environmental change.

  26. Reviews

    1. What happens to plant mitochondria under low oxygen? An omics review of the responses to low oxygen and reoxygenation

      RACHEL SHINGAKI-WELLS, A. HARVEY MILLAR, JAMES WHELAN and REENA NARSAI

      Article first published online: 11 MAY 2014 | DOI: 10.1111/pce.12312

      Floods can submerge plants, limiting oxygen availability and hindering energy supplies. Flood tolerant plants, such as rice, are able to adequately respond to low oxygen by successfully re-modelling primary and mitochondrial metabolism to partially counteract the energy crisis that ensues. Here we discuss how plants respond to low oxygen stress at the transcriptomic, proteomic, metabolomic and enzyme activity levels, particularly focussing on mitochondria and interacting pathways.

  27. Original Articles

    1. Are solar UV-B- and UV-A-dependent gene expression and metabolite accumulation in Arabidopsis mediated by the stress response regulator RADICAL-INDUCED CELL DEATH1?

      LUIS O. MORALES, MIKAEL BROSCHÉ, JULIA P. VAINONEN, NINA SIPARI, ANDERS V. LINDFORS, ÅKE STRID and PEDRO J. APHALO

      Article first published online: 6 MAY 2014 | DOI: 10.1111/pce.12341

      Wild-type Arabidopsis Col-0 and rcd1-1 were used in field experiments to study the roles of RADICAL-INDUCED CELL DEATH1 (RCD1) in the regulation of gene expression and metabolite accumulation under solar ultraviolet (UV) radiation. RCD1 was not directly involved in UV-B-regulation of genes with functions in UV acclimation, hormone signaling and stress related markers. In addition, RCD1 had no role on PDX1 accumulation but modulated the UV-B-induction of flavonoid accumulation in leaves of Arabidopsis exposed to solar UV. We concluded that RCD1 does not play an active role in UV-B signaling but rather modulates UV-B responses under full spectrum sunlight.

  28. Reviews

    1. New clues for a cold case: nitric oxide response to low temperature

      JULIETTE PUYAUBERT and EMMANUEL BAUDOUIN

      Article first published online: 6 MAY 2014 | DOI: 10.1111/pce.12329

      Although nitric oxide (NO) is now recognized as a versatile actor of stress signalling networks in plants, its involvement in cold stress responses emerged very recently. During the past few years, the identification of proteins and genes targeted by NO signalling, together with the key functions of these targets for cold tolerance, supported the importance of NO for establishing tolerance to low temperature. This review summarizes our current knowledge on this topic by addressing different aspects of NO signalling (generation and removal, impact on protein function and gene expression, overall impact on cold response) and proposing directions for future investigations.

  29. Original Articles

    1. Implications of the mesophyll conductance to CO2 for photosynthesis and water-use efficiency during long-term water stress and recovery in two contrasting Eucalyptus species

      F. JAVIER CANO, ROSANA LÓPEZ and CHARLES R. WARREN

      Article first published online: 5 MAY 2014 | DOI: 10.1111/pce.12325

      Recent years have seen increasing interest in mesophyll conductance (gm) as a key component of plant carbon balance, especially under water deficit. Exposure of Eucalyptus spp. to long-term water deficit highlighted the important role of gm in provoking higher intrinsic water use efficiency (iWUE) and lower leaf oxidative stress of water stressed plants. Additionally we discuss potential sources of error that may bias estimation of gm and developed new equations to simulate the effect of resistance to refixation of CO2 on estimates of gm.

    2. In situ measurement of leaf chlorophyll concentration: analysis of the optical/absolute relationship

      CHRISTOPHER PARRY, J. MARK BLONQUIST Jr. and BRUCE BUGBEE

      Article first published online: 5 MAY 2014 | DOI: 10.1111/pce.12324

      In situ optical meters are widely used to estimate leaf chlorophyll concentration, but non-uniform chlorophyll distribution causes a highly non-linear optical/absolute relationship. Over 30 publications have reported absolute/optical relationships, but in vitro chlorophyll extraction and measurement techniques are not standardized, environmental effects on single-leaf chlorophyll distribution are not well characterized, and differences among replicate meters have not been rigorously assessed. The results of this study more rigorously link in situ optical measurements with absolute chlorophyll concentration and provide insight to strategies for single-leaf radiation capture among diverse species.

    3. Dynamics of leaf water relations components in co-occurring iso- and anisohydric conifer species

      FREDERICK C. MEINZER, DAVID R. WOODRUFF, DANIELLE E. MARIAS, KATHERINE A. MCCULLOH and SANNA SEVANTO

      Article first published online: 28 APR 2014 | DOI: 10.1111/pce.12327

      There is considerable interest in determining if iso- versus anisohydric species are more likely to die during severe droughts, but explicit comparisons of the plasticity of their leaf water relations components have rarely been made. We compared responses of shoot water relations components to changes in plant water status in co-occurring anisohydric Juniperus monosperma and isohydric Pinus edulis. In J monosperma, the shoot water potential and relative water deficit at the turgor loss point as well as the tissue bulk modulus of elasticity dynamically tracked changes in shoot water potential, whereas these properties were static in P. edulis. The contrasting behavior of their shoot water relations components may be associated with their contrasting modes of regulation of plant water status and may be representative of anisohydric and isohydric species in general. Plasticity of shoot water relations components in J. monosperma may contribute to its greater capacity to withstand severe drought.

    4. Proton cellular influx as a probable mechanism of variation potential influence on photosynthesis in pea

      VLADIMIR SUKHOV, OKSANA SHERSTNEVA, LYUBOV SUROVA, LYUBOV KATICHEVA and VLADIMIR VODENEEV

      Article first published online: 28 APR 2014 | DOI: 10.1111/pce.12321

      Variation potential, induced by local heating, inactivates photosynthesis and activates respiration in pea (Pisum sativum L.). Variation potential generation is accompanied with pH increase in apoplasts and decrease in cytoplasm, which probably reflects H+-ATPase inactivation and H+ influx during this electrical event. This proton cellular influx is the probable mechanism of VP influence on photosynthesis in pea; several means of action for this influence are possible.

    5. Water relations of Robinia pseudoacacia L.: do vessels cavitate and refill diurnally or are R-shaped curves invalid in Robinia?

      RUIQING WANG, LINGLING ZHANG, SHUOXIN ZHANG, JING CAI and MELVIN T. TYREE

      Article first published online: 25 APR 2014 | DOI: 10.1111/pce.12315

      Since 2005 an unresolved debate has questioned whether R-shaped vulnerability curves (VCs) might be an artifact of the centrifuge method of measuring VCs. VCs with R-shape show loss of stem conductivity from approximately zero tension and if true this suggests that some plants either refill embolized vessels every night or function well with a high percentage of vessels permanently embolized. In this paper we provide evidence that the R-shaped curve in Robinia is an artifact of air bubbles generated during the measurement stem conductivity in a Cochard Cavitron, because stem conductivity falls to very low values with repeated measurement while holding tension constant.

    6. Differential responses of plasma membrane aquaporins in mediating water transport of cucumber seedlings under osmotic and salt stresses

      ZHENG-JIANG QIAN, JUAN-JUAN SONG, FRANÇOIS CHAUMONT and QING YE

      Article first published online: 14 APR 2014 | DOI: 10.1111/pce.12319

      It has long been recognized that inhibition of plant water transport by either osmotic stress or salinity is mediated by aquaporins (AQPs). By applying PEG or NaCl stress at the osmotic strength to cucumber seedlings, and monitoring changes in plant hydraulic properties and the expression patterns of plasma membrane AQP (PIPs), we demonstrated differential responses of CsPIPs in mediating water transport of cucumber seedlings, and the regulatory mechanisms differed according to applied stresses, stress durations, and specific organs.

  30. Reviews

  31. Original Articles

    1. Relax and refill: xylem rehydration prior to hydraulic measurements favours embolism repair in stems and generates artificially low PLC values

      PATRIZIA TRIFILÒ, FABIO RAIMONDO, MARIA A. LO GULLO, PIERA M. BARBERA, SEBASTIANO SALLEO and ANDREA NARDINI

      Article first published online: 7 APR 2014 | DOI: 10.1111/pce.12313

      Recent reports have suggested that diurnal changes in embolism level of stems might arise as a consequence of air entry into xylem conduits upon cutting stems while under substantial tension, and xylem rehydration procedures prior to hydraulic measurements have been recommended to avoid this artefact. Here, we show that xylem rehydration favours embolism repair, thus leading to records of stem hydraulic conductance erroneously higher than those actually experienced by transpiring plants. Our data call for renewed attention to procedures of sample collection in the field and transport to the laboratory.

  32. Reviews

    1. Molecular and physiological responses of trees to waterlogging stress

      JÜRGEN KREUZWIESER and HEINZ RENNENBERG

      Article first published online: 7 APR 2014 | DOI: 10.1111/pce.12310

      Climate models predict more severe and more frequent waterlogging periods as a consequence of global climate change. Despite their ecological, economic and social importance, the response of trees to such stress is far from being understood. This review summarizes the present knowledge on tree internal responses to waterlogging and highlights molecular and physiological features controlling the flooding tolerance of trees.

  33. Original Articles

    1. Turnover time of the non-structural carbohydrate pool influences δ18O of leaf cellulose

      XIN SONG, GRAHAM D. FARQUHAR, ARTHUR GESSLER and MARGARET M. BARBOUR

      Article first published online: 20 MAR 2014 | DOI: 10.1111/pce.12309

      In the mechanistic model of cellulose δ18 O, the biochemical parameter pex describes the proportion of organic exchange with the environmental water when sucrose is being converted to plant cellulose. In this study, we collected physiological and isotopic data from leaves of Ricinus communis grown in various environmental conditions, to test the hypothesis that variation in pex is related to variation in the turnover time (τ) of non-structural carbohydrate pool available for cellulose synthesis. Our data analysis yielded evidence for the presence of significant, positive relationship between pex and τ, thereby lending support to the above hypothesis. The observed variation in pex in association with τ has important implications for the interpretation of plant cellulose δ18 O data in environmental/ecological studies.

    2. The mechanism of improved aeration due to gas films on leaves of submerged rice

      PIETER VERBOVEN, OLE PEDERSEN, QUANG TRI HO, BART M. NICOLAI and TIMOTHY D. COLMER

      Article first published online: 20 MAR 2014 | DOI: 10.1111/pce.12300

      In brief, we show that internal aeration of leaf tissues with gas films is greatly enhanced as a result of the fast diffusion of O2 in the gas phase and also due to the large area of collection (the air water interface). In contrast, removal of the leaf gas films (in the proposed model) results in critically low internal O2 concentration which is in good agreement with experimental data already obtained for rice and other terrestrial wetland plants. The combined effects of diffusive boundary layer, gas film, cuticle permeability, stomata, and mesophyll respiration is for the first time comprehensively unraveled using mechanistic modeling.

    3. Group VII Ethylene Response Factor diversification and regulation in four species from flood-prone environments

      HANS van VEEN, MELIS AKMAN, DIAAN C. L. JAMAR, DICK VREUGDENHIL, MAARTEN KOOIKER, PETER van TIENDEREN, LAURENTIUS A. C. J. VOESENEK, M. ERIC SCHRANZ and RASHMI SASIDHARAN

      Article first published online: 19 MAR 2014 | DOI: 10.1111/pce.12302

      Group VII Ethylene Response Factors (ERFs) are involved in adaptation of rice and Arabidopsis to flooding. This study shows how this transcription factor family diversified amongst the angiosperms from two ancestral loci. Group VII ERFs were found to be involved in the submergence response of four wild species from flood-prone environments, but showed distinct expression patterns dependent primarily on their phylogenetic origin.

    4. Biochemical and molecular characterization of rice (Oryza sativa L.) roots forming a barrier to radial oxygen loss

      KONSTANTIN KULICHIKHIN, TAKAKI YAMAUCHI, KOHTARO WATANABE and MIKIO NAKAZONO

      Article first published online: 16 MAR 2014 | DOI: 10.1111/pce.12294

      We analyzed metabolic profiles and gene expression profiles in roots of rice (Oryza sativa L.) plants grown under stagnant deoxygenated conditions, which induce suberization in the outer cell layers (OCL) of the roots and formation of strong barrier to radial oxygen loss (ROL). Distinctive biochemical features of rice roots under stagnant conditions were the accumulations of malic acid and very long chain fatty acids (VLCFAs). The appearance of VLCFAs occurred simultaneously with a dramatic decrease of ROL from the root to the external medium. Based on a tissue-specific gene expression analysis, we propose that the physiological role of malic acid accumulation in rice roots grown under stagnant conditions is to provide a substrate for the biosynthesis of fatty acids/VLCFAs in the OCL, which in turn are used in the biosynthesis of suberin.

    5. Interplays between nitric oxide and reactive oxygen species in cryptogein signalling

      ANNA KULIK, ELODIE NOIROT, VINCENT GRANDPERRET, STÉPHANE BOURQUE, JÉRÔME FROMENTIN, PAULINE SALLOIGNON, CAROLINE TRUNTZER, GRAŻYNA DOBROWOLSKA, FRANÇOISE SIMON-PLAS and DAVID WENDEHENNE

      Article first published online: 12 MAR 2014 | DOI: 10.1111/pce.12295

      The interplays between nitric oxide ( NO ) and reactive oxygen species ( ROS ) in the defense responses triggered by the elicitin cryptogein in tobacco cells were investigated. Both NO and ROS resulting from NADPH oxidase activity contribute to cryptogein-induced cell death and regulate the expression of genes encoding ubiquitine ligases. In turn, peroxynitrite mitigates the effects of NO and ROS .

    6. Ethylene plays an essential role in the recovery of Arabidopsis during post-anaerobiosis reoxygenation

      KUEN-JIN TSAI, SHU-JEN CHOU and MING-CHE SHIH

      Article first published online: 12 MAR 2014 | DOI: 10.1111/pce.12292

      This study investigated the role of ethylene in the reoxygenation stage after anaerobiosis. The results showed that gene transcripts involved in ROS detoxification, dehydration response and metabolic processes were regulated during reoxygenation. Moreover, ethylene signaling may participate in regulating these responses and maintaining the homeostasis of different phytohormones.

    7. Characterization of distinct root and shoot responses to low-oxygen stress in Arabidopsis with a focus on primary C- and N-metabolism

      ANGELIKA MUSTROPH, GREGORY A. BARDING JR, KAYLA A. KAISER, CYNTHIA K. LARIVE and JULIA BAILEY-SERRES

      Article first published online: 12 MAR 2014 | DOI: 10.1111/pce.12282

      Oxygen deficiency stress leads to significant changes in plant metabolism. Here, root and shoot responses to oxygen deficiency stress were compared at the level of the transcriptome and metabolome using the model plant Arabidopsis thaliana. Differences in fermentation metabolism were discerned between the two organs, specifically root-specific GABA and lactate formation, which could be only partially explained by transcriptome data. The study identified several exciting avenues for future studies, such as details of the mechanism of GABA and Ala accumulation and the roles of metabolite and ion transporters.

    8. Partial versus complete submergence: snorkelling aids root aeration in Rumex palustris but not in R. acetosa

      MAX HERZOG and OLE PEDERSEN

      Article first published online: 6 MAR 2014 | DOI: 10.1111/pce.12284

      Some terrestrial wetland plants respond to submergence by elongating the petiole or stem to restore air contact, a phenomenon referred to as snorkelling. We showed that snorkelling greatly enhanced root aeration in Rumex palustris but not at all in R. acetosa owing to the 36-fold higher resistance to gas diffusion in the petiole of R. acetosa.

    9. LESION SIMULATING DISEASE 1 and ENHANCED DISEASE SUSCEPTIBILITY 1 differentially regulate UV-C-induced photooxidative stress signalling and programmed cell death in Arabidopsis thaliana

      WERONIKA WITUSZYŃSKA, MAGDALENA SZECHYŃSKA-HEBDA, MIROSŁAW SOBCZAK, ANNA RUSACZONEK, ANNA KOZŁOWSKA-MAKULSKA, DAMIAN WITOŃ and STANISŁAW KARPIŃSKI

      Article first published online: 5 MAR 2014 | DOI: 10.1111/pce.12288

      Because of stratospheric ozone depletion, UV has become more and more dangerous to the biosphere. Therefore, it is important to understand UV perception and signal transduction in plants. In the present study we show that LESION SIMULATING DISEASE 1 (LSD1) and ENHANCED DISEASE SUSCEPTIBILITY 1 (EDS1) are antagonistic regulators of UV-C induced programmed cell death (PCD) in A rabidopsis thaliana. Moreover, we demonstrate that chloroplasts are the first organelles that show features of UV-C induced damage, which may indicate their primary role in PCD development.

    10. Physiological and transcriptomic characterization of submergence and reoxygenation responses in soybean seedlings

      BISHAL G. TAMANG, JOSEPH O. MAGLIOZZI, M. A. SAGHAI MAROOF and TAKESHI FUKAO

      Article first published online: 24 FEB 2014 | DOI: 10.1111/pce.12277

      Complete submergence at the early seedlings stage is a major environmental constraint for soybean production worldwide. As floodwaters subside, submerged seedlings are abruptly exposed to oxygen, which induces oxidative stress. This study defined the fundamental physiological and transcriptomic responses to submergence and reoxygenation in soybean at the seedling establishment stage, highlighting conserved, organ-specific, and species-specific adjustments that enhance adaptability to the two stresses in the major legume species, Glycine max.

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