Book of Abstracts - Geyseco

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P - Posters ponents are required for local and/or systemic effects of CDR1 and avoids possible secondary or pleiotropic effects arising from chronic over-expression of CDR1 throughout development. Furthermore, to explore how CDR1 is integrated within the disease resistance signal network and to position CDR1 relative to other key players such as small molecule signals like ROS and salicylic acid, and signal transduction proteins like NPR1, EDS1, PAD4 and DIR1, we have crossed TA:CDR1 plants with the following key mutant/transgenic phenotypes: npr1-1, eds1-1, pad4-5, dir1- 1, rboh D, rboh F, rboh D/F and sid 2-2. ROS production, cell death and defence response have been analyzed to determine which signalling molecules are required for both, local and systemic effects of CDR1. (1) Xia et al., Embo Journal, 2004, 23: 980-988 * Lamb CJ was sadly departed on August 2009 Funded by Marie Curie Actions-European re-integration Grants (FP7-PEOPLE-2007-2-2-ERG) Project nº 208146 P17-051: NITROGEN TRANSPORTS CAN ACT AS NA- TURAL SWITCHES FOR PLANT RESISTANCE SIGNA- LING García-Agustín, P.* - Camañes, G. – Pastor, V. – Vicedo, B. – Cerezo, M. – Flors, V. Universitat Jaume I *Corresponding author e-mail: garciap@camn.uji.es Nitrogen levels have been associated to enhanced susceptibility of plants to different pathogens. However, a mutation in a high affinity nitrate transporter (HATS) codified by NRT2.1 enhances basal resistance and is not associated with different nitrate levels in normally fertilized plants. The nrt2 mutant shows lower susceptibility to Pseudomonas syringae with reduced disease rates and lower bacterial growth inside the plant tissue. The reduced susceptibility could be linked to a primed SA-dependent signaling together with a reduced CORONATIN sensitivity. Several bioassays have demonstrated that nrt2 is primed for the PR1 expression and SA levels upon Pst infection. In addition, nrt2 neither closes stomata at late time points after COR application nor enhances H2O2 production upon effector treatment. Coronatine less Pst DC3118 produces reduced symptoms on Ws background while it grows as Pst DC3000 in nrt2.1. Accordingly to SA priming, ABA and JA levels do not change in nrt2.1 during infection, but increase in wild-type plants. This establishes a possible link between nitrate transporters and plant responses to biotic stresses. Microarray analysis confirm the relevance of one of the branches of SA synthesis. Interestingly, the expression of many ribosomal proteins is also affected in the atnrt2 mutant upon Pst infection. Further genetic analyses show that AtNRT2.1 displays atypical regulation upon different stimuli and is tightly coordinated with AtNRT2.2 and AtNRT3.1. P17-052: DIFFERENTIAL EXPRESSION OF PLANT GE- NES INVOLVED IN GIBBERELLINS METABOLISM DU- RING THE EARLY STEPS OF MEDICAGO TRUNCATU- LA / GIGASPORA MARGARITA INTERACTION Ortu, G. – Küster, H. – Balestrini, R. – Bonfante, P. Department of Plant Biology, University of Turin (Italy) – IPP- CNR Keywords: arbuscular mycorrhiza, Medicago truncatula, Gigaspora margarita, gibberellins. Arbuscular mycorrhizas are symbioses established between the roots of most land plants and fungi belonging to Glomeromycota (Smith & Read 2008). While plants acquire minerals from the fungal partner improving their nutrient status, symbiotic fungi directly uptake organic carbon from their hosts. The improved nutrient status has a positive impact on whole plant physiology influencing growth, protection from diseases and cause important impact at the transcriptomic and cellular level (Hohnjec et al 2005). During colonization plant cells undergo strong modifications in order to accommodate the penetrating hyphae: in epidermal cells an ephemeral apparatus, the pre-penetration apparatus, is assembled (Genre et al 2005) at the moment of surface contact between the partners. The aim of the work was to identify plant genes which were differentially regulated during the early steps of M. truncatula-G. margarita interaction and to focus on genes potentially involved in gibberellins metabolism. A microarrays analysis on RNA extracted from M. truncatula transformed roots segments collected at the first contact with G. margarita appressoria showed an up regulation of 534 gene in the wild type respect to the mycorrhiza-defective dmi3-1 mutant. Out of them, 6 genes were found involved in different steps of gibberellins biosynthesis. Preliminary experiments in q-RT real time PCR confirm the upregulation of two genes involved in gibberelin pathway: GID1L3, a predicted gibberellin receptor and GA2oxydase7 involved in gibberellin catabolism. P17-053: IDENTIFICATION AND CHARACTERIZATION OF A PUTATIVE MYB TRANSCRIPTION FACTOR DU- RING THE SYMBIOSIS BETWEEN LOTUS JAPONICUS AND GLOMUS INTRARADICES Volpe, V.¹– Güether, M.¹ - Dell´Aglio, E.¹ - Costa A.² - Ruberti, C.² - Lo Schiavo, F.² - Bonfante, P.¹ ¹Department of Plant Biology, University of Turin (Italy) – IPP- CNR ²Department of Biology, University of Padova (Italy) Keywords: arbuscular mycorrhiza symbiosis, Lotus japonicus, Glomus intraradices, transcription factors, RNA interference Arbuscular mycorrhizas (AMs) are very common symbioses established between land plants and soil fungi, where both partners benefit by nutritional exchanges. Transcriptome analysis of L. japonicus using microarray has identified a large number of genes whose expression is altered in mycorrhizal roots. Among them, 47 code for proteins involved in transport and 24 genes code for potential transcription factors (TF) (Guether et al., 2009). One of them, a putative MYB-TF, is the second highest regulated gene of the whole array with 20,000 fold over-expression in mycorrhizal roots (Guether et al., 2009). The aim of this work is to analyze the role of the putative MYB-TF and to understand whether i) it is dispensable for arbuscular mycorrhiza symbiosis and ii) it is involved in the regulation of nutrient exchange processes. To investigate the specific role of the LjMYB protein in mycorrhizal processes we first developed silenced lines using RNAi (RNA interference) technology. We also generated transgenic hairy root lines, constitutively expressing the LjMYB gene, in order to obtain a deeper view of its functional meaning. The expression levels of LjMYB in two RNAi hairy root lines analyzed were reduced in respect to the control lines. The frequency of mycorrhizal colonization in RNAi-line1 was similar to the control lines, but the number of arbuscules was increased. As a further step, we analyzed the subcellular localization of MYB in Tobacco-leaf protoplasts expressing the chimeric p35S::EGFP::MYB gene: the signal was localized to the nucleus, indicating a role as a TF for the LjMYB protein. P17-054: SULFUR STARVATION AND NITROGEN FIXA- TION IN NODULATED PEA PLANTS (PISUM SATIVUM L.) Muñoz-Azcárate, O. – Aldasoro, J. - Arrese-Igor, C. Universidad Pública de Navarra Sulfur deficiency is receiving an increased attention as a limiting factor in cropping systems, although there is scarce information on its effect on biological N fixation (BNF). This can be an important field of study since nitrogen-fixing symbioses between legume plants and rhizobia are the largest natural source of nitrogen for agriculture and these symbioses are very sensitive to abiotic stresses. A few studies have reported a decreased nodule performance P
FESPB 2010 - XVII Congress of the Federation of European Societies of Plant Biology under S-deficient conditions. However, it is not well established yet whether this effect can be mainly attributed to an impairment of nodule development or nodule metabolism.Nodulated pea seedlings were grown in an aerated hydroponic solution in a controlled environment. A group of plants was transferred to a modified S-free solutionthe day of transplanting (S0 plants), and another group was transferred to the S-free solution seven days after transplanting (DAT) (S7 plants). BNF, photosynthesis, nodule biomass and root and shoot length and biomass were measured 28 DAT.Sulfur starvation resulted in a significant yield reduction of shoots, roots and nodules in S0 plants, but no significant effect was found in S7 plants. Also, BNF and photosynthesis in S0 plants showed a significant reduction when compared with control plants, while S7 plants showed no significant differences with control plants. Thus, it appears that S starvation is critical at the early stages of nodulation, being the negative effects mostly due to a lower nodule development.This work has been supported by the Ministry of Science and Innovation (Spain; AGL2008- 0069/AGR). OMA is the recipient of a fellowship from MSI (FPI Programme). P17-055: GENETIC STUDIES OF MAMP-TRIGGERED IMMUNITY IN ARABIDOPSIS Tintor, N. – Reimer, EM. - Schulze-Lefert, P. – Saijo, Y. Max Planck Institute for Plant Breeding Research Plants recognize the presence of microbes through the perception of molecular structures typical of a microbial class, termed microbe-associated molecular patterns (MAMPs). In Arabidopsis, the Leu-rich repeat receptor-like kinases FLS2 and EFR recognize the bacterial MAMPs flagellin and EF-Tu (and their bioactive epitopes flg22 and elf18), respectively. Perception of these MAMPs triggers defense responses that restrict microbial invasion and growth. However, the molecular basis of MAMPtriggered immunity is still largely unknown. A forward genetic approach revealed priority in sweet life (psl) mutants that show de-repressed anthocyanin accumulation in the presence of elf18. Previously identified PSL genes encode for components of an ER-resident protein folding and maturation pathway that is recquired for the generation of functional EFR. psl25 plants are partially and differentially defective in elf18 but not flg22 responses and hypersusceptible to a bacterial phytopathogen, Pseudomonas syringae. Map-based cloning revealed a mutation in the PSL25 locus that encodes for a key enzyme in the ER N-glycosylation pathway. psl36 plants are impaired in responses to both flg22 and elf18, despite wild type-like accumulation and ligandbinding activity of FLS2 and EFR. This points to a role of PSL36 in post-recognition signaling of both receptors. Further characterization of psl25 and psl36 plants is underway. P17-056: CELL WALL AND PLANT STRESS RESPONSES. THE ENDO-Β-1,4- GLUCANASES ALTER THE RESIS- TANCE TO PATHOGENS IN ARABIDOPSIS Finiti, I.¹ - Leyva, M.O.¹ - Vicedo, B.² - Real, M.D.¹ - García- Agustín, P.² - González-Bosch, C.¹ ¹Universitat de Valencia, IATA (CSIC) ²Universitat Jaume I Plant Endo-β-1,4-glucanases (EGases) depolymerize polysaccharides containing 1,4-β-D-glucan linkages and take part in cell wall editing processes such as elongation, fruit ripening and floral abscission. EGases are localized both in the membrane and secreted in the wall depending on their specific role.Plant cell wall modification is a critical component in the stress response and several cell wall modifying enzymes have been recently reported as important factors of resistance or susceptibility. In Arabidopsis the GH9 family consists of 25 members. A sequenced genome and ease of genetic manipulation is yielding information about the biological roles of many members of this family. Data from the Affymetrix microarray analyses revealed that some of them are differentially regulated upon several biotic and abiotic stresses. Here we show a linkage between the lack of EGase activity and the biotic stress response in Arabidopsis. Knockout plants lacking individual EGases showed altered resistance to Botrytis cinerea and Pseudomonas syringae. Both the redundancy of the EGase gene family and the complexity of the cell wall matrix degradation prevent severe phenotypes of single mutants. Nevertheless, the observed infection phenotypes were dependent on the mutated gene and were associated to changes of SA-, JAand ABAsignaling pathways and callose deposition. In conclusion, our data support that EGase activity is part of the complex web of cell wall signaling and metabolism operating in response to plant–pathogen interactions. P17-057: THE DEFENSOME MODEL FOR RICE INNATE IMMUNITY Ko Shimamoto* Ikoma (Nara - Japan) *Corresponding author e-mail: simamoto@bs.naist.jp We have been studying molecular signaling in rice innate immunity by studying the small GTPase OsRac1 and its interacting proteins by using a variety of exerimental methods. We have identified a number of OsRac1-interacting proteins and studied their functions and interactions with other proteins. We found that OsRac1 interacts withtwo types of receptors; membrane-boundreceptor-like kinases and NB-LRR type receptors. OsRac1forms a protein network with several cheperones and co-chaperones, SGT1, RAR1, Hsp90, Hsp70, and Hop/Sti1. A scaffloding protein, RACK1, also interacts with OsRac1. The OsRac1 network includes enzymes such as NADPH oxidase and CCR which are important for immune responses. Based on genetic, protein-protein interaction, and biochemical studies we propose thatthese proteins form acomplex termed ‘defensome’ which plays an important role in rice innate immunity. The defensome model proposes that proteins used in PTI and ETI are largely shared and OsRac1 acts as a molecular switch for both types of immune responses in rice. New data to support our model will be presented. P17-058: BIPHASIC PRODUCTION OF ETHYLENE AND ROS IS AN IMPORTANT COMPONENT FOR DETERMI- NING STRESS TOLERANCE IN RESPONSE TO BIOTIC STRESS Wi, S.* - Park, K.Y. Sunchon National University *Corresponding author e-mail: akrp@sunchon.ac.kr The relationship between ROS accumulation and ethylene production in response to biotic stress with the fungal pathogen, Phytophthora parasitica var. nicotianae, was investigated using stress-tolerant transgenic plants, in which ethylene biosynthesis or signaling and ROS production were impaired. It was observed that wild-type tobacco plants exhibited a gene-specific expression of NtACS members in response to Phytophthora infection. It seemed that pathogen treatment led to the peaked-expression of NtACS4 at 1 h for stress signaling and of NtACS1 at 72 h for necrosis during phase II. The profile of pathogen-induced ROS accumulation, determined by DAB and qRT-PCR for NADPH oxidase, RbohD and RbohF, was also showed a biphasic pattern which took place early. ROS accumulation was peaked twice at 1 h and 48 h after pathogen treatment. ROS accumulation was rapidly increased at post-inoculation from 36 h to 48 h, when transcript of RbohD was also increased. Pathogen-induced RbohD expression and ROS accumulation at phase I were significantly suppressed in stress-tolerant transgenic plants, in which ethylene biosynthesis and signaling were impaired. Biphasic ethylene production was also inhibited, especially at 1 h, in stress-tolerant transgenic plants with impairment of RbohD and F expression. Therefore, these results implied that ROS could act as a signal
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Page 206 and 207: Author Index Aarts, M.G. S18-002 Ab
Page 208 and 209: Cattivelli, L. P01-031 Cawly, J. P1
Page 210 and 211: Gallego, B. P17-037 Gallego, P.P. P
Page 212 and 213: Kersten, B. P10-017 Keskin, O. P05-
Page 214 and 215: Miguel, C. S02-001, P01-122 Milhinh
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Page 218 and 219: Tanimoto, E. P01-045 Tarakanov, I.
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