Book of Abstracts - Geyseco

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P - Posters plasma membrane, in pH-banding and carbon acquisition. We have recently described plasma membrane domains that can be stained by the endocytic tracers FM1-43 and FM4-64 as well as by the sterol marker filipin. Here we show that these domains are also labelled by the plasma membrane specific dye NBD C6-sphingomyelin, suggesting plasma membrane invaginations, and by Lysotracker red, suggesting acidification. A comparison between the pH-banding pattern and the distribution of plasma membrane areas revealed that size, density and area fraction of plasma membrane domains are significantly higher at the acidic bands as compared with the alkaline regions. Furthermore, the plasma membrane domains are recognized by an antibody against a H+-ATPase which recognizes a 100 kDa band on SDS gels and which preferentially binds to charasomes on ultrathin sections from high pressure frozen cells. Our data suggest that charasomes provide regions separated from the bulk medium by a convoluted diffusion path. H+ exported to such regions will be slower to diffuse away and, hence will be more effective at generating a locally low pH at the cell surface. In such H+-extrusion areas carbonic anhydrases may mediate the dehydration of HCO3- and locally increase the availability of CO2. P11-010: FREE POLYAMINES AND POLYAMINES CATA- BOLISM DURING SENESCENCE OF BARLEY LEAVES Sobieszczuk-Nowicka, E. 1 *- Bagniewska-Zadworna, A. 1 - Pietrowska- Borek, M. 2 - Legocka, J. 1 1 Adam Mickiewicz University, Poland 2 oznan University of LifeSciences *Corresponding author, e-mail: evaanna@rose.man.poznan.pl Leaf senescence represents a key developmental phase in the life of plants. It is a period of massive mobilization of nitrogen, carbon and minerals from the mature leaf to other parts of the plant. Senescence of barley leaves is a highly regulated process and involves cessation of photosynthesis, disintegration of chloroplasts, breakdown of leaf proteins, loss of chlorophyll and removal of amino acids. Significant chromatin condensation, internucleosomal fragmentation of nuclear DNA and enhanced expression of cysteine proteases in senescing mesophyll prove that leaf senescence is a genetically defined process involving mechanisms of programmed cell death. Changes in free polyamines and their catabolism have been shown to occur in leaf senescence of barley. A feature of this is an increase in diamine and polyamine oxidases expression and activity. The reduction of polyamines titer, mainly spermidine and spermine, throught the process suggests that it might be the process inducer. Hydrogen peroxide produced by polyamines oxidases may act as signal molecule or as cytotoxic agent. Besides, there is other possible role for free polyamines in senescence: regulation of the expression of senescence-related genes. Acknowledgment: this work was supported by Polish Ministry of Science and Higher Education research grant N N303 418236. P11-011: COMPARTMENT SPECIFIC LOCALIZATION OF GLUTATHIONE AND ITS PRECURSORS DURING ENVIRONMENTAL STRESS SITUATIONS Müller, M.* - Zechmann, B. Institute of Plant Sciences, University of Graz *Corresponding author, e-mail: maria.mueller@uni-graz.at Glutathione as an antioxidant is involved in the detoxification of reactive oxygen species, which are commonly formed during various environmental stress situations. Glutathione metabolism involves highly compartment specific pathways and limitations in the ability of glutathione to protect the plant against stress situations can only be detected if glutathione contents are analyzed at the subcellular level. For this purpose an immunogold cytohistochemical approach was developed and adapted to different plant material in order to detect and quantify subcellular glutathione and its precursors with computer-supported transmission electron microscopy [1,2]. These studies showed that the distribution of glutathione is similar in different plant species (Arabidopsis thaliana, Cucurbita pepo, Nicotiana tabacum, Beta vulgaris). The accuracy of the glutathione-labeling method was supported by different observations. First pre-adsorption of the anti-glutathione antisera with glutathione reduced the density of the gold particles to background levels. Second, the overall glutathione-labeling density was reduced by about 90% in leaves of the glutathione-deficient Arabidopsis mutant pad2-1 and increased in plants with enhanced glutathione accumulation. Further studies showed changes in the compartment specific distribution of glutathione and its precursors during abiotic and biotic stress situations (e.g. heavy metal, virus infection) and demonstrate the compartment specific importance of glutathione metabolism for plant defense. This work was supported by the Austrian Science Fund (FWF P16273, P18976, P20619). 1. Zechmann B. et al., J.Microscopy 55 (2006) p173. 2. Zechmann B. et al., J. Exp. Bot. 59 (2008) p 4017. P11-012: TOWARDS A COMPREHENSIVE MODEL FOR SETTING UP ENDOPOLYPLOIDIZATION DURING TO- MATO FRUIT DEVELOPMENT Bourdon, M. 1 * - Coriton, O. 2 - Cheniclet, C. 1 - Brown, S. 3 - Peypelut, M. 4 - Chevalier, C. 1 - Renaudin, J.P. 1 - Frangne, N. 1 1 Biologie du Fruit, INRA et Université de Bordeaux, Centre INRA Bordeaux-Aquitaine, France 2 Amélioration des Plantes et Biotechnologies Végétales, Plateforme Cytogénétique Moléculaire Végétale, INRA, Université de Rennes, France 3 Institut des Sciences du Végétal, UPR 2355 CNRS, Gif-sur- Yvette, France 4 Pôle Imagerie du Végétal, Bordeaux Imaging Center, Bordeaux, France *Corresponding author, e-mail: matthieu.bourdon@bordeaux. inra.fr In the course of plant development, increased ploidy levels (referred to as Endopolyploidization) are frequently observed in vegetative and/or reproductive organs of many Angiosperm species. Endopolyploidization consists in a nuclear DNA duplication in the absence of subsequent mitosis and cell division. Despite its strong occurrence, little is known about its functional role [1, 2]. In tomato (Solanum lycopersicum), we have shown that most pericarp cells undergo Endopolyploidization duringfruit development [3]. To go further in the elucidation of the functional role of Endopolyploidization, we decided to address its onset in the course of fruit development in close relationship with cell expansion and differentiation. The use of FISH methodology allowed to consider Endopolyploidization at different levels. First, we analysed the spatial organization of chromosomes in endopolyploid cells and showed that the chromosomes are polytenic, the sister chromatids remaining attached to the same centromere. Then we established a model for ploidy distribution in the tomato pericarp tissue, by assessing the ploidy level of nuclei in their tissue context, thus opening the way towards a detailed description of pericarp development. Such a distribution, correlated with an acquisition of highly specific cell features (cell size, nuclear morphology and mitochondria distribution at the nucleus periphery) during fruit growth provided us with some essential clues in order to clarify the intricate relationship between Endopolyploidization and cell differentiation, in the context of fruit development. 1E. dgar and Orr-Weaver, Cell, 297-306, 105 (2001) 2J.oubès & Chevalier, Plant Mol. Biol., 735-745, 43 (2000) 3. Cheniclet et al., Plant Physiol., 1984-1994, 139 (2005) P11-013: SHAPING A PROTUBERANCE - THE MECHA- NICS OF CELLULAR GROWTH Chebli, Y.1* - Aouar, L.1 - Fayant2 - Anja Geitmann1 P
FESPB 2010 - XVII Congress of the Federation of European Societies of Plant Biology 1 Institut de Recherche en Biologie Végétale - Université de Montréal 2 Ecole Polytechnique de Montréal *Corresponding author, e-mail: youssef.chebli@yahoo.ca Cellular growth in plant cells is driven by the turgor pressure but controlled by the mechanical properties of the cell wall. The formation of a cellular protuberance requires the spatially confined yielding of the wall. Using finite element modeling, a technique used in engineering, we established a theoretical model of tip growth as it occurs in pollen tubes and root hairs. The model predicts that a characteristic spatial distribution of mechanical properties in the cell wall is required to produce the self-similar growth pattern that characterizes these cell types. The mechanical profile is characterized by a steep increase in cell wall extensibility in the transition zone between dome-shaped apex and cylindrical region of the cell. To compare the theoretical requirements with the biological reality, we quantitatively assessed the spatial distribution of various cell wall components in the pollen tube wall of Lilium and Arabidopsis. We used immunofluorescence methods combined with quantitative image analysis to locate pectin, cellulose and callose. We found remarkable agreement between the expected gradient in cell wall extensibility and the distribution of de-esterified pectin polymers. Furthermore, we identified the orientation of cellulose microfibrils using scanning electron microscopy and found that their mechanical support is particularly important in the transition region. Callose on the other hand provides mechanical support to the cylindrical shank of the cell. Our data show that tip growth is produced by a highly controlled interplay of cell wall assembly processes and that each component is important for different aspects governing the shape and growth dynamics of the elongating cell. P11-014: KUNITZ TRYPSIN INHIBITOR AS A PLANT CELL DEATH MODULATOR Komarova, T.* - Sheval, E. - Dorokhov, Y. Moscow State University, A.N.Belozersky Institute *Corresponding author, e-mail: t.v.komarova@gmail.com Normally plant cell is adapted for producing large amounts of protein which is targeted and stored in special cellular compartments. But intensive uncontrolled and untargeted protein production is likely to result in programmed cell death (PCD). To study cell death of protein overexpressing plant cell we created specific vector system, TMV:GFP, allowing GFP production in huge amounts and resulted in cells death 3 days after agroinjection. Using microscopy and biochemical approaches we described the following features of the process: stages of cell and tissue death; GFP behavior in aggregates and its proper folding. Moreover we analyzed the pattern of mRNA expression in Nicotiana benthamiana tissues just before their death using subtractive hybridization. Several candidate genes including specific biotic cell death-associated protein (CDM) were found to be upregulated. NbCDM appeared to have strong homology with Kunitz trypsin inhibitors (KTI) family which is specific for serine proteases been implicated in PCD in plants. Joint expression of NbCDM under control of 35S promoter (35S-NbCDM) with TMV:GFP resulted in enhanced lesion development whereas 35S-NbCDM per se didn’t induce necrotisation. Upregulation of NbCDM expression was also registered as a response to virulent bacterial pathogen Ralstonia solanacearum or even after its NLS-containing protein overexpression. Asit is well known that PCD requires a coordinate activation of different factors such as proteases and suppressors, NbCDM is likely to be one of such players inhibiting and modulating these processes. P11-015: GENERATION OF NITRIC OXIDE UNDER ANOXIA IS INDEPENDENT OF NITRATE REDUCTASE ACTIVITY. Kingston-Smith, A.* - Eelen, I. - Davies, T.E. - Mur, L.A.J. - Aberystwyth University *Corresponding author, e-mail: ahk@aber.ac.uk Exposure of plants to abiotic stress causes changes in foliar protein which can affect crop yield and quality. This is also true of plant parts ingested by grazing ruminants whereby leaf cells are exposed to multiple stresses (heat, anoxia, microbial attack) in the hours following rumen entry causing autolysis. This has implications for the poor use of feed N by ruminants, which results in N deposition on land (as animal wastes) and contributes to N2O generation. As the cell signal NO has been implicated in cell death under biotic and abiotic stress this work investigated its potential role in control of autolysis in ingested plant cells. NO was detected in Arabidopsis thaliana Col-0 leaf discs after in vitro exposure to rumen-stress conditions. The source of NO generation in plants is currently unknown but could occur enzymically (catalysed by nitrate reductase; NR) or non-enzymically, an is enabled by an increase in intracellular nitrite under low oxygen conditions. The role of NR in NO generation under anoxia was determined by exposure of leaf discs from Col-0 and mutants Nia 1, Nia 2 and AtNos (which had 56%, 5% and 100% of NR activity of Col-0) to rumen-like conditions. NO was detectable by fluorescence microscopy in all lines after 1h. These results, plus no significant differences in foliar nitrite suggest that non-enzymic NO production in ingested plant cells could be responsible for autolysis. P11-016: ASYNCHRONOUS DEATH OF STOMATA GUARD CELLS PREDETERMINED BY THE ASYMME- TRIC OPEN MITOSIS Selga, T.* - Maija, S. Faculty of Biology, University of Latvia *Corresponding author, e-mail: turs.selga@lu.lv The control of programmed cell death (PCD) by previous asymmetric cell division (ACD) in plants is far from clear. The stomatal cell lineage is a typical example of precisely planned series of ACDs, that finish with as if symmetrical division of the guard mother cell (GMC) to form identical stomatal guard cells (GC) (Hove and Heidstua 2008, Nodeau 2009, Dong et al 2009) We searched among several hundreds of stomata in various stages of their development and senescence from the young, full grown and senescing leaves of tobacco (Nicotiana tabacum L.) by use of several methods and techniques of cyochemistry and microscopy. Our data suggests that the stomatal GMCs in reality always divide spatially asymmetrically by the classic open mitosis and develop unequal GCs, that age and die differently by different alterations of their nuclei and other organelles. Perinuclear endoplasmic reticulum in one of sister cells disappears faster than in another. The GMCs and GCs always are structurally joined at least with one nucleus of adjacent cell and migration of variously stained nuclear substance among them is evident. The permanent plastid-nuclear complex (PNCs) that we have repeatedly demonstrated in photosynthesizing cells of different vascular plants exists in all GMCs and GCs during all their lifespan, and evidently are important control units. P11-017: IDENTIFICATION OF PHOSPHORYLATED RESIDUES IN THE H+-ATPASE AND PHYSIOLOGICAL CONSEQUENCES OF THE EXPRESSION OF AN ACTI- VATED FORM IN THE PLANT Duby, G.* - Piette, A.S. - Piotrowiak, D. - Salladini, A. - Boutry, M. Institut des Sciences de la Vie, Université Catholique de Louvain *Corresponding author, e-mail: geoffrey.duby@uclouvain.be The plasma membrane H+-ATPase is building a proton electrochemical gradient that activates secondary transporters. It is involved, in cytosolic pH regulation, cell elongation and stomata aperture. It contains an auto-inhibitory C-terminal region and is
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FESPB 2010 - XVII Congress of the F
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POST 04 POSTERS • Environmental S
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Author Index Aarts, M.G. S18-002 Ab
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Cattivelli, L. P01-031 Cawly, J. P1
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Gallego, B. P17-037 Gallego, P.P. P
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Kersten, B. P10-017 Keskin, O. P05-
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Miguel, C. S02-001, P01-122 Milhinh
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Ramiro, M. P09-018 Ramon, M P13-002
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Tanimoto, E. P01-045 Tarakanov, I.
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