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Plant, Cell & Environment

Cover image for Vol. 35 Issue 6

June 2012

Volume 35, Issue 6

Pages 1013–1184

  1. Original Articles

    1. Top of page
    2. Original Articles
    1. You have free access to this content
      Arabidopsis thaliana TERMINAL FLOWER2 is involved in light-controlled signalling during seedling photomorphogenesis (pages 1013–1025)

      ANA ELISA VALDÉS, KRISTINA RIZZARDI, HENRIK JOHANNESSON, ALESSIA PARA, ANNIKA SUNDÅS-LARSSON and KATARINA LANDBERG

      Article first published online: 9 JAN 2012 | DOI: 10.1111/j.1365-3040.2011.02468.x

      The participation of TERMINAL FLOWER2 (TFL2), the Arabidopsis thaliana HETEROCHROMATIN PROTEIN1 homolog, in light signalling has been proposed due to the early flowering and reduced sensitivity to day length displayed by tfl2 mutants. We report that TFL2 affects the phytochrome-dependent light signalling during seedling photomorphogenesis, and that light-dependent auxin-regulated genes are misexpressed in tfl2 plants. Moreover, TFL2 interacts with the IAA5 and IAA19 proteins, suggesting that TFL2 might be involved in regulation of phytochrome-mediated light responses through auxin action.

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      Stand structure modulates the long-term vulnerability of Pinus halepensis to climatic drought in a semiarid Mediterranean ecosystem (pages 1026–1039)

      CRISTINA MORENO-GUTIÉRREZ, GIOVANNA BATTIPAGLIA, PAOLO CHERUBINI, MATTHIAS SAURER, EMILIO NICOLÁS, SERGIO CONTRERAS and JOSÉ IGNACIO QUEREJETA

      Article first published online: 30 DEC 2011 | DOI: 10.1111/j.1365-3040.2011.02469.x

      We investigated whether stand structure modulates the long-term physiological performance and growth of Pinus halepensis Mill. in a semiarid Mediterranean ecosystem. The combined interpretation of latewood δ13C and δ18O and tree ring width series indicated that pines in dense afforested stands were consistently more water stressed and had lower stomatal conductance, photosynthetic rate and radial growth than pines in open woodlands for the last 40 years. In this semiarid ecosystem, the benefits of negligible inter-tree competition for water in open woodlands clearly outweigh potential benefits derived from enhanced infiltration and reduced runoff losses in dense afforested stands, thus rendering the latter more vulnerable to projected increases in drought frequency and duration across the Mediterranean region.

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      Changes in stomatal conductance along grass blades reflect changes in leaf structure (pages 1040–1049)

      T. W. OCHELTREE, J. B. NIPPERT and P. V. V. PRASAD

      Article first published online: 6 JAN 2012 | DOI: 10.1111/j.1365-3040.2011.02470.x

      We investigated the coordinated change in leaf structure and function along grass blades. Photosynthesis and stomatal conductance increased acropetally from base to tip, which was correlated with a decreased pathlength for the movement of water from the vascular bundle to stomate. The decreased pathlength for water movement should allow greater stomatal conductance while minimizing the water potential gradient across the leaf mesophyll. These results highlight the tight correlation between changes in leaf structure and function within individual grass blades.

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      Modelling photosynthetic responses to temperature of grapevine (Vitis vinifera cv. Semillon) leaves on vines grown in a hot climate (pages 1050–1064)

      DENNIS H. GREER and MARK M. WEEDON

      Article first published online: 30 DEC 2011 | DOI: 10.1111/j.1365-3040.2011.02471.x

      Semillon grapevines are grown in hot climates of Australia and this has a major effect on photosynthesis and, therefore, growth and development of the vines. A question arises as to whether the stomata or the physiology of photosynthesis is affected by the high temperatures. Our results showed stomata do limit photosynthesis by as much as 30% but the photosynthetic processes related to carboxylation of Ribulose 1, 5-bisphosphate are the most important limitations to photosynthesis at high temperatures and impact on carbon fixation. Strategies to reduce leaf temperatures, therefore, are needed to maintain productivity in these and potentially future hotter climates.

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      Universality of phloem transport in seed plants (pages 1065–1076)

      KÅRE HARTVIG JENSEN, JOHANNES LIESCHE, TOMAS BOHR and ALEXANDER SCHULZ

      Article first published online: 6 JAN 2012 | DOI: 10.1111/j.1365-3040.2011.02472.x

      The phloem of gymnosperms differs in some important aspects from the respective sugar-conducting tissue in angiosperms which offers a low-resistance pathway from source to sink, well matching the transport mechanism postulated by Münch 80 years ago. To test universality of the Münch mechanism, we compiled anatomical data for 32 angiosperm and 38 gymnosperm trees with heights spanning less than 1 m up to 50 m. The species studied showed a remarkable correlation with the scaling predictions found recently, when optimizing the Münch mechanism theoretically using a simple resistor model. The central finding of this work is that all seed plants are geometrically optimized for rapid translocation in the phloem and that the flow conductivity is significantly lower in gymnosperms than in angiosperms of similar height, but compatible with the Münch mechanism.

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      The Arabidopsis aquaporin PIP1;2 rules cellular CO2 uptake (pages 1077–1083)

      NORBERT UEHLEIN, HENRIK SPERLING, MARLIES HECKWOLF and RALF KALDENHOFF

      Article first published online: 30 DEC 2011 | DOI: 10.1111/j.1365-3040.2011.02473.x

      Membrane CO2 flux into Arabidopsis mesophyll cells was studied using pH microelectrodes. Cellular CO2 transport was affected when expression of the aquaporin AtPIP1;2 was knocked out. The results provide new arguments for the ongoing debate about the validity of the lipid bilayer model system and the Meyer-Overton rule for cellular gas transport. In conclusion, we suggest a modified view on molecular gas transport mechanisms in living cells.

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      The impact of light intensity on shade-induced leaf senescence (pages 1084–1098)

      BASTIAAN BROUWER, AGNIESZKA ZIOLKOWSKA, MATTHIEU BAGARD, OLIVIER KEECH and PER GARDESTRÖM

      Article first published online: 6 JAN 2012 | DOI: 10.1111/j.1365-3040.2011.02474.x

      Although shade can promote leaf senescence, the mechanisms and signaling pathways by which senescence is induced remain elusive. Here, we investigated the threshold beyond which leaf senescence overrules photosynthetic acclimation by studying the physiological mechanisms that regulate the induction of leaf senescence in response to increasing levels of shade. We show that in response to shade, leaves adjust their metabolism to lower their Light Compensation Point and maintain a positive carbon balance in order to repress the induction of senescence.

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      A new screening technique for salinity resistance in rice (Oryza sativa L.) seedlings using bypass flow (pages 1099–1108)

      BUALUANG FAIYUE, MOHAMMED J. AL-AZZAWI and TIMOTHY J. FLOWERS

      Article first published online: 6 JAN 2012 | DOI: 10.1111/j.1365-3040.2011.02475.x

      A lack of screening techniques delays progress in research on salinity resistance in rice. In this study, we report that an apoplastic pathway (the so-called bypass flow) causes a difference in salt resistance between rice genotypes and can be used as a new screening technique in screening for salinity resistance.

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      Plasmodesmatal pores in the torus of bordered pit membranes affect cavitation resistance of conifer xylem (pages 1109–1120)

      S. JANSEN, J.-B. LAMY, R. BURLETT, H. COCHARD, P. GASSON and S. DELZON

      Article first published online: 16 JAN 2012 | DOI: 10.1111/j.1365-3040.2011.02476.x

      This study tested the hypothesis that air-seeding in a conifer tracheid occurs through minute pores in the central thickening of the bordered pit membrane (i.e. torus). Plasmodesmatal pores were reported in tori of 13 conifer species using electron microscopy. Evidence for embolism spreading via punctured tori is supported by the pore sizes, which corresponds relatively well with the pressure inducing cavitation, and the finding that species with punctured tori are significantly less cavitation resistant than species with non-punctured tori.

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      Coordination of a mitochondrial superoxide burst during the hypersensitive response to bacterial pathogen in Nicotiana tabacum (pages 1121–1136)

      MARINA CVETKOVSKA and GREG C. VANLERBERGHE

      Article first published online: 16 JAN 2012 | DOI: 10.1111/j.1365-3040.2011.02477.x

      This work shows that the hypersensitive response of tobacco leaf to the bacterial pathogen Pseudomonas syringae is preceded by an early and persistent burst of superoxide in the mitochondrion. This burst appears to be sustained by suppression of the major mitochondrial mechanism to avoid superoxide generation by the electron transport chain (alternative oxidase) and suppression of the sole enzymatic means to scavenge mitochondrial superoxide (manganese superoxide dismutase). Based on these studies, it is suggested that alternative oxidase and manganese superoxide dismutase are uniquely positioned to impact both the strength and specificity of reactive oxygen species (ROS) signals in the mitochondrion and that coordination of their activities represents a potential means to construct multiple distinct mitochondrial ROS signatures.

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      Expression and tissue-specific localization of nitrate-responsive miRNAs in roots of maize seedlings (pages 1137–1155)

      SARA TREVISAN, ALBERTO NONIS, MAURA BEGHELDO, ALESSANDRO MANOLI, KLAUS PALME, GIOVANNI CAPORALE, BENEDETTO RUPERTI and SILVIA QUAGGIOTTI

      Article first published online: 28 JAN 2012 | DOI: 10.1111/j.1365-3040.2011.02478.x

      The knowledge of post-transcriptional regulation of plant response to nutrients is important to improve nitrogen use efficiency of crop. Our work was aimed at understanding the role of miRNAs in the molecular control of maize response to nitrate. Six nitrate responsive miRNAs were identified in roots of young seedlings and their expression was deeply studied in response to nitrate supply, through both qPCR and in situ hybridization. Results obtained pointed out the potential role of nitrate-responsive miRNAs at the posttranscriptional level in the regulation of the metabolic, physiological and morphological adaptations of maize seedling survival under nitrate-deficient conditions.

      Corrected by:

      Corrigendum

      Vol. 35, Issue 7, 1358, Article first published online: 11 JUN 2012

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      Wheat WRKY genes TaWRKY2 and TaWRKY19 regulate abiotic stress tolerance in transgenic Arabidopsis plants (pages 1156–1170)

      CAN-FANG NIU, WEI WEI, QI-YUN ZHOU, AI-GUO TIAN, YU-JUN HAO, WAN-KE ZHANG, BIAO MA, QING LIN, ZHENG-BIN ZHANG, JIN-SONG ZHANG and SHOU-YI CHEN

      Article first published online: 3 FEB 2012 | DOI: 10.1111/j.1365-3040.2012.02480.x

      WRKY-type transcription factors are involved in multiple aspects of plant growth and development. Their roles in abiotic stress tolerance are largely unknown especially in crops. Here, we find that TaWRKY2 and TaWRKY19 from wheat play differential roles in abiotic stress tolerance through activation of different downstream genes.

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      Adaptive strategies of Parietaria diffusa (M.&K.) to calcareous habitat with limited iron availability (pages 1171–1184)

      SILVIA DONNINI, PATRIZIA DE NISI, DAMIANO GABOTTI, LILIANA TATO and GRAZIANO ZOCCHI

      Article first published online: 6 FEB 2012 | DOI: 10.1111/j.1365-3040.2012.02481.x

      Parietaria diffusa (M.&K.) is a plant able to survive in highly calcareous soils without displaying any chlorotic symptoms. By taking into account these characteristics, we have investigated the existence of Strategy I complementary/alternative mechanism(s) involved in Fe solubilisation and uptake. Beyond the classical responses of Strategy I plants, Parietaria shows a greater production and exudation of phenolics and organic acids when grown in the presence of bicarbonate. Accordingly, some metabolic rearrangements and an increase in the activity of enzymes belonging to the shikimate pathway occurred.

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