Book of Abstracts - Geyseco

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02 - PS - Parallell Sessions Lectures of FERONIA and on our search for additional components of this signal transduction process using genetic and biochemical approaches. Our recent attempts to identify novel components of the FERONIA signal transduction pathway have identified surprising links to disease resistance in plants. The evolutionary implications of these findings will be discussed. PS05: BIOTECNOLOGY Session lead lectures PS05-001: METABOLIC AND TRANSPORT ENGINEE- RING OF GLUCOSINOLATES Halkier, B. A.* Department of Plant Biology, Faculty of Life Sciences, University of Copenhagen *Corresponding author, e-mail: bah@life.ku.dk Epidemiological studies have demonstrated reduced risk of developing cancer upon consumption of diets rich in cruciferous vegetables. Key players in this chemoprevention are the natural products glucosinolates, in particular the methionine-derived glucoraphanin which is highly abundant in broccoli. Improved nutrition by functional foods or health-promoting dietary supplements is an attractive means for prevention of lifestyle-based diseases. Towards this goal, we have transferred the entire glucoraphanin biosynthetic pathway consisting of thirteen genes from Arabidopsis into the non-cruciferous tobacco by transient expression. The engineering involves the chloroplast-localized chain elongation machinery (5 genes) that converts methionine to dihomomethionine, and the cytosolic, ER-anchored core structure pathway (8 genes) that converts dihomomethionine to the glucoraphanin. Transport engineering is important to ensure efficient channeling of intermediates between compartments and proper storage of end product to prevent feedback inhibition, but not much attention has so far been given to this aspect of engineering. Our progress in development of a technology platform for transport engineering will be discussed, as will our technology platform for engineering plant pathways into yeast. 1) Mikkelsen et al. (2010) Reconstitution of the glucoraphanin biosynthetic pathway. Molecular Plant (in press)Ç PS05-002: TRANSGENIC NUTRITIONAL ENHANCE- MENT: THE PRODUCTION OF OMEGA-3 LONG CHAIN POLYUNSATURATED FATTY ACIDS IN PLANTS Napier, J.* - Sayanova, O. - Ruiz-Lopez, N. - Haslam, R. - Venegas-Caleron, M. Rothamsted Research, Harpenden, Herts AL5 2JQ, UK *Corresponding author, e-mail: johnathan.napier@bbsrc.ac.uk There is now considerable evidence as to the importance of omega-3 long chain polyunsaturated fatty acids (LC-PUFAs) in human health and nutrition. Unfortunately, current sources are either in severe decline (fish oils) or expensive (via microbial fermentation), leading to the search for an alternative source. We have been evaluating the possibility of producing omega-3 LC- PUFAs in transgenic plants, to provide a sustainable source of these important nutrients, since no native higher plant species synthesise these fatty acids. We have transgenically assembled the primary biosynthetic pathway for LC-PUFAs in both model plants and crop species. Our data indicate that whilst the transgenic synthesis of C20 LC-PUFAs such as arachidonic acid and eicosapentaenoic acid is clearly feasible, a number of factors may limit the efficient heterologous reconstitution of this pathway. We have attempted to address this problem in a systematic manner by firstly identifying different metabolic “bottlenecks” and then seeking genetic interventions to overcome them. It seems likely that a generic bottleneck resides within the primary LC-PUFA biosynthetic pathway as a result of the “substrate dichotomy” between the lipid-dependent desaturases and the acyl-CoAdependent elongases which catalyze the reactions. Attempts to overcome this bottleneck, through the use of acyl-CoA dependent desaturase or acyltransferases will be presented. In addition, the impact (in terms of substrate-channelling) of endogenous plant lipid metabolism on the heterologous LC-PUFA pathway will be considered. The outcomes from our recent iterations of this transgenic metabolic engineering will be presented, and the future prospects for GM-derived LC-PUFAs will be discussed. PS06: ROOT BIOLOGY Session lead lectures PS06-001 AUXIN RESPONSE AND CELL COMMUNICA- TION IN EMBRYONIC ROOT FORMATION Weijers, D.* Laboratory of Biochemistry, Wageningen University *Corresponding author, e-mail: dolf.weijers@wur.nl Plant growth and development is controlled through the activity of stem cells within specialized niches, the meristems. These meristems are first established in the early embryo, when the organism consists of few cells. The work in my group aims at understanding the mechanisms underlying the initiation of the root meristem in the early embryo. Root initiation is first manifested by the specification of an extraembryonic suspensor cell as the hypophysis, the future quiescent center. This cell specification event is triggered by signals from the adjacent embryonic cells. The auxin-dependent transcription factor AUXIN RESPONSE FACTOR5 / MONOPTEROS (ARF5/MP) is a critical regulator of hypophysis specification, and acts in the embryonic lineage to promote cell-cell communication. We have recently identified a number of direct MP target genes, and among these found a small mobile bHLH transcription factor that acts as a novel intracellular signal that mediates MP-dependent root formation. MP also promotes transport of auxin to the hypophysis. However, the response machinery in this cell is not known. In a systematic effort to define auxin-dependent patterning steps and ARF gene expression patterns, we have found a novel auxin response module that operates in the extra-embryonic suspensor to promote hypophysis specification, but also to prevent transformation to embryonic cell fate. Hence, auxin triggers several different responses in the early embryo, depending on the cellular context. Our current focus is to 1) dissect MP-dependent cell-cell communication, 2) understand the basis for context-dependent auxin responses in the embryo and 3) identify the gene networks that are controlled by auxin in the different cell types of the embryo. PS06-002 TOWARD NEW REGULATORY NETWORKS IN THE ROOT MERISTEM Blilou, I.* Department of Molecular Genetics, Utrecht University, The Netherlands *Corresponding author, e-mail: i.blilou@uu.nl In the Arabidopsis root meristem, a dynamic transcription factor networks regulate stem cell specification and meristem maintenance. One of the best studied subnetworks is that involving the SHR/SCR GRAS family transcription factors. It involves transmission of positional information between cell layers in the meristem. We have previously shown that JKD (a C2H2 type transcription factor) regulates SHR movement and nuclear localization. Here we provide evidence that new members of the JKD clade act redundantly in this process, we show that their expression overlaps with JKD in the ground tissue and that they form protein complexes with SHR to control asymmetric cell division in the ground tissue. We also show that JKD controls epidermal cell fate and thus root hair patterning. PS
FESPB 2010 - XVII Congress of the Federation of European Societies of Plant Biology PS07: MOLECULAR MECHA- NISM OF ABIOTIC STRESS Session lead lectures PS07-001 TARGETING PROTEIN KINASE SIGNALING CASCADES TO IMPROVE STRESS TOLERANCE IN PLANTS Hirt, H.* URGV Plant Genomics, Evry, France *Corresponding author, e-mail:Hirt@evry.inra.fr Signal transduction pathways relay information of the extracellular environment to the cellular interior, most often resulting in changes in gene expression programmes. Signalling pathways are highly conserved modules that are most commonly composed of a number of protein kinases that phosphorylate and thereby change the activity of their respective target proteins. Because the activation of a signaling pathway generally changes expression of a large number of genes, failure or modification of the activity of signalling pathways are often related to pathologic conditions in man, animals and plants. However, careful modification of protein kinases can also have beneficial effects for the organisms as evidenced by the enhanced tolerance against environmental conditions or pathogen attack. Therefore protein kinases are ideal targets for genetic modification as well as biochemical agonists and antagonists. The usefulness and potential of targeted protein kinase approaches will be discussed with respect to the potential to improve plant performance. PS07-002 NEW ROLES OF THE POLYAMINE CATABO- LIC PATHWAY IN STRESS RESPONSES Roubelakis-Angelakis, K.* - Moschou, P.N. - Angelini, R. - Fincato, P. - Federico, R. - Tavladoraki, P. Department of Biology, University ‘Roma Tre’,Rome, Italy *Corresponding author, e-mail: poproube@biology.uoc.gr The stress-induced Polyamine exodus into the apoplast reveals a novel signalling pathway leading either to tolerance-effector responses or to execution of cell death, depending on the level of apoplastic H 2 O 2 . Engineering the PA catabolic pathway leads to increased tolerance to biotic and sensitivity to abiotic stress. The pathway is controlled partially by abscissic acid (ABA). ABA induces expression of AtPAO3, a peroxisomal Arabidopsis PAO and GUS activity post-treatment with ABA is localized to guard cells, implying a direct role of PAO-derived H 2 O 2 in stomatal closure. Moreover, the identification and analysis of AtPAOs in Arabidopsis reveals that all four AtPAO1-4 backconvert Spm to Spd and additionally AtPAO2 and AtPAO3 backconvert Spd to Put. Thus, Arabidopsis seems to lack PAOs involved in terminal catabolism of PAs in contrast to maize, in which the until now characterized PAOs produce 1,3-diaminopropane and 4-aminobutanal or N-(3-aminopropyl)-4-aminobutanal from Spd or Spm oxidation, respectively. Additionally, the organ/tissue specific expression of AtPAOs implies functional diversity inside the AtPAOs family. Surprisingly, H 1 -NMR studies reveal that AtPAOs produce 3-aminopropanal from their substrates, which can be further converted to the osmoprotectant molecule β-alanine and pantothenate in a pairwise reaction. All these results along with the involvement of AtPAOs in catabolism of thermospermine, a Spm isomer involved in vascular differentiation and stress adaptation, reveal novel roles of the PA catabolic pathway. PS08: PHOTOSYNTHESIS & RESPIRATION Session lead lectures PS08-001 PHOTOSYNTHETIC LIMITATIONS IN RESPI- RATORY MUTANT PLANTS Flexas, J.* - Florez-Sarasa, I.D. - Galle, A. - Medrano, H. - Ribas-Carbo, M. Grup de Recerca en Biologia de Plantes en Condicions Mediterranies, Departament de Biologia, Universitat de les Illes Balears *Corresponding author, e-mail: jaume.flexas@uib.es Under stress conditions, plant growth and survival is often limited due to reductions of plant carbon balance, which is dependent on the balance between photosynthesis and respiration. Although both processes are intimately linked, photosynthesis responses to mitochondrial alterations remain relatively poorly evaluated. Here we review the current knowledge on photosynthesis responses of respiratory mutants. In general, any knockout or anti-sense reduction in a protein involved in respiration results in altered photosynthesis rates, although by different mechanisms. For instance, when protein impairments lead to potentially decreased availability of ATP, such as depleted mitochondrial Complex I or decreased fumarase, it results in impaired photosynthesis due to restricted CO2 diffusion due to reduced stomatal and mesophyll conductances to CO2. In contrast, impairments resulting in increased availability of NADH in mitochondria (e.g., cytochrome oxidase and/or alternative oxidase in mitochondrial electron transport chain) decrease photosynthesis by limiting chloroplast electron transport rate, presumably operated by a mechanism involving the malate valve. Similarly, impairments likely resulting in reduced Gly to Ser interconversion for photorespiration induce a metabolic limitation to photosynthesis. Surprisingly, impairing some proteins such as MDH or aconitase results in increased rather than decreased photosynthesis. The implications of these findings are discussed. PS08-002 REACTIVE OXYGEN SPECIES AND RETRO- GRADE SIGNALLING FROM MITOCHONDRIA AND CHLOROPLASTS Møller, I. M.* Department of Genetics and Biotechnology, Aarhus University *Corresponding author, e-mail: ian.max.moller@agrsci.dk Reactive oxygen species (ROS) production increases in plants under stress. ROS can damage cellular components, but they can also act in signal transduction to help the cell counteract the oxidative damage in the stressed compartment. H 2 O 2 might induce a general stress response, but it does not have the required specificity to selectively regulate nuclear genes required for dealing with localized stress, e.g., in chloroplasts or mitochondria. I will here argue that peptides deriving from proteolytic breakdown of oxidatively damaged proteins have the requisite specificity to act as secondary ROS messengers and regulate source-specific genes and in this way contribute to retrograde ROS signalling during oxidative stress. Likewise, unmodified peptides deriving from the breakdown of redundant proteins could help coordinate organellar and nuclear gene expression. PS09: NATURAL VARIATION & ADAPTATION Session lead lecture PS09-001 GENETICS OF ADAPTATION AND SPECIA- TION IN MIMULUS Willis, J.* Duke University *Corresponding author, e-mail: jwillis@duke.edu How do new species arise? What is the genetic basis of adaptations and reproductive isolating barriers, and what does this tell us about how they evolved? Here we take advantage of the on-
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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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