Book of Abstracts - Geyseco

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P - Posters good. Stems constitute major portion of the yield, both amount and quality. We have examined the role of different flowering pathways (vernalization, photoperiod, GA) on the regulation of canopy structure in different timothy genotypes. Timothy flowers when critical day length exceeds and it does not require double induction for flower induction. Our results show that vernalization enhances flowering and the number of flowering tillers. There exists difference between genotypes in the flowering rate and number of flowering tillers after vernalization. Transcript of two flowering genes, VRN1 and VRN2, were examined after vernalization. The level of VRN1 expression remained high during prolonged vernalization. The role of VRN2 gene is unclear in timothy. In 12 h photoperiod all examined genotypes remained at a vegetative stage, but in 16 h these genotypes formed flowers. A single GA treatment didn´t affect flower formation in timothy similarly as it has been shown for example in Lolium temulentum. Our preliminary results show that the regulation of flowering induction in timothy is unique compared to other grasses, ad currently we are analyzing sequencing data on various flowering pathways. P04-017: STUDYING THE MOLECULAR REGULATION OF VERNALIZATION IN LILY Zaccai, M.*- Lugassi-Ben Hamo, M. – Mazor, I. Ben Gurion University *Corresponding author e-mail: mzaccai@bgu.ac.il In lily (Lilium longiflorum), bulb vernalization is not only an obligatory requirement for flowering, but also the most important factor affecting flowering time and quality. However, the molecular regulation of the response to vernalization and of floral transition remains largely unclear in lily. Evidence mainly obtained from Arabidopsis and wheat indicates that the general pattern of the vernalization response, namely a floral repressor inhibited by cold exposure, is conserved among different species. Yet, the type of genes involved in the process differ between species. To identify candidate genes involved in the vernalization response in lily we took a differential expression approach. Lily bulbs were vernalized at 4oC (V) or kept at 25oC (Non Vernalized, NV) for 9 weeks and subtractions libraries were generated to detect differentially expressed genes from V and NV meristems. Clone sequences were analyzed using annotations databases. Overall transcription (amount of mRNA from total RNA), as well as homology to known genes were much higher in V than in NV meristems. Clones from the subtraction libraries showed homology to genes involved in dormancy, chromatin modification and floral transition. This study represents a first step towards elucidation of the molecular regulation of vernalization in lily, and addresses fundamental questions regarding the conservation of the vernalization response among higher plants. Vernalization-related genes could be used in the future, to manipulate this trait in important crops. P04-018: IMPROVEMENTS ON MICROSPORE EMBR- YOGENESIS INDUCTION IN OLIVE: EFFECT OF VA- RIOUS ENDOGENOUS AND EXOGENOUS FACTORS Prem, D.¹* - Bueno, MA.² – Testillano, PS.¹ - Risueño, MC.¹ ¹Centro de Investigaciones Biológicas, CSIC ²CIFOR-INIA *Corresponding author e-mail: deepakandrewprem@gmail.com DP and MAB contributed equally to this work. The existing knowledge for the switchover from gametophytic to embryogenic pathway of microspores in trees is still scarce. Induction of microspore embryogenesis in olive has been reported by the development of isolated microspores in vitro system (1), and cellular markers of the reprogramming process have been characterized (2). In this work we have studied several critical endogenous (plant genotype, time of bud collection, microspore stage, thermal pre-treatment) and exogenous (media composition, carbon source, stress treatments after microspore isolation, culture temperature, cell density) factors that affect microspore embryogenesis induction. Some modifications on the pre-treatment, processing and microspore isolation methods have been developed to improve the protocol of the culture system. Monitoring of the microspore development and multicellular proembryo formation was accomplished by cytochemistry at light and fluorescence microscopy. Cold pre-treatment of buds and cold treatment of isolated microspores with or without starvation inducing agents such as polyols showed a marked increase in frequency of embryogenesis induction. A cell density of 20 – 50,000 cells was essential to keep a congenial osmotic environment and the choice of carbon source had a marked effect on the development of embryogenic cells. Maltose provided an appropriate osmotic balance leads to the development of multicellular structures. These new insights offer several clues to fine tune the microspore embryogenesis process in olive. Bueno et al. 2005. Acta Physiol. Plantarum 27, 695-702. Solís et al. 2008. Plant Sci. 174, 597-605. Work supported by MICINN projects AGL2008-04255 and BFU2008-00203. P04-019: UNCOUPLING DELLAS FROM GA-SIGNA- LLING DURING ARABIDOPSIS FRUIT DEVELOPMENT Fuentes, S.¹* - Alvey, L.² - Ljung, K.³ - Sorefan, K.4 – Harberd, N.P. ² - Østergaard, L.¹ ¹John Innes Centre ²University of Cambridge, Department of Plant Sciences ³Umeå Plant Science Centre 4University of East Anglia *Corresponding author e-mail: sara.fuentes@bbsrc.ac.uk Fruit initiation and fruit development ensure the efficient survival and dispersal of flowering plants. These processes are energetically costly and, consequently, fruit development is tightly controlled by a complex regulatory network. The hormone gibberellin (GA) plays a pivotal role in this network and previous studies have shown that GA promotes growth by inducing degradation of the growth-repressing DELLA proteins. However, the extent to which DELLA proteins contribute to GA-mediated gynoecium and fruit development remains to be clarified. To shed light on this area, we provide an in-depth characterisation of the role of DELLA proteins in fruit-set and growth. We show that DELLA proteins not only regulate reproductive organ size but are also involved in the control of wider aspects of plant sexual reproduction. By utilising the facultative parthenocarpy phenotype of della mutants we show that RGL1 and RGL2 are major repressors of pistil growth in the absence of fertilisation. And, for the first time, we demonstrate the existence of a DELLA-independent GA response which functions during fruit development. Our results show that DELLA proteins are key regulators of gynoecium and fruit development. Moreover, control of GA-signalling during fruit development is likely to rely on additional levels of complexity as suggested by the existence of a DELLA-independent GA response. P04-020: GENETIC AND HORMONAL CONTROL BY IN- DEHISCENT FOR FRUIT PATTERNING IN ARABIDOP- SIS Girin, T.¹* - Sorefan, K.¹ - Arnaud, N.¹ - Paicu, T.² - Fuentes, S.¹ - O’Brien, M.² - Wood, T.¹ - Sablowski, R.¹ - Smyth, D.R.² - Østergaard, L.¹ ¹John Innes Centre ²Monash University *Corresponding author e-mail: girint@bbsrc.ac.uk The bHLH transcription factor INDEHISCENT (IND) is essential to pattern the Valve Margins (VMs), which are specialised tissues where dehiscence of the silique takes place to release the seeds at maturity. We have previously shown that IND regulates P
FESPB 2010 - XVII Congress of the Federation of European Societies of Plant Biology the expression of PID and WAG2 kinase genes, thus affecting the subcellular localisation of PIN auxin efflux carriers and creating an auxin minimum necessary for VM formation. Our recent work, primarily based on expression analysis and ChIP experiment, has led to the identification of two other IND-dependant pathways required for proper development of VM tissues. IND directly regulates Gibberellins biosynthesis, which appears to be crucial as a local depletion in bioactive Gibberellins affect the formation of VMs. IND also directly activates the expression of SPATULA (SPT), a bHLH-encoding gene previously described in the patterning of other fruit tissues. IND and SPT proteins interact when expressed in epidermal onion cells and in yeast, and the analysis of over-expressing Arabidopsis lines suggests that this interaction is important for the function of the proteins in planta. Finally, phenotypic analysis of single and double mutants shows that IND and SPT are together required for the patterning of several fruits tissues ; this leads to the identification of previously unknown roles for IND in stigma and transmitting tract formation and for SPT in VM development. Cross talks between the three IND-regulated pathways involved in VM patterning will be discussed. P04-021: B-FUNCTION MADS-BOX GENES IN LEGU- MES: GENE DUPLICATION AND SUBFUNCTIONALI- ZATION IN MEDICAGO TRUNCATULA Roque, E.* - Rochina, MC. – Serwatowska, J. – Yenush, L. - Beltrán J.P. - Cañas L.A. Instituto de Biología Molecular y Celular de Plantas (CSIC- UPV) *Corresponding author e-mail: edroque@ibmcp.upv.es Using the MADS-box of the AmDEFICIENS gene as a probe to screen a floral cDNA library of Medicago truncatula, we have isolated four B-function genes involved in the specification of petal and stamen identity: two APETALA 3 (MtAP3 and MtN- MH7) and two PISTILLATA (MtPI and MtNGL9) orthologs. The expression patterns of these genes have been studied by in situ hybridization analysis and we have also performed two-hybrid assays to identify possible protein-protein interactions. Both MtPI and MtNGL9 proteins lack the PI motif described as essential for the functionality of PISTILLATA in Arabidopsis. Using RNAi and Tnt1 mutagenesis, we generated MtPI loss-of-function mutants. These plants showed flowers with sepaloid petals and carpelloid stamens. Our results suggest that the differences in the functional constrictions among the paralogs MtPI and MtNGL9 could have generated a high degree of structural conservation in MtPI, which maintains a predominant role during floral development, whereas MtNGL9 could have accumulated mutations in the expression activation elements of the regulatory regions, in addition to acquiring new cis-regulatory elements, thus providing new spatial expression patterns. Therefore, these genes could have followed a quantitative subfunctionalization process in parallel, followed by a possible neofunctionalization process. The M. truncatula AP3 orthologs could have undergone a qualitative subfunctionalization with the subsequent partition of the ancestral functions. This hypothesis is reinforced by the non-overlapping spatial expression patterns in the 2nd and 3rd floral whorls and by the phenotypes of partial loss-of-B function in both mutants. P04-022: GENOME-WIDE ANALYSIS OF FLORAL OR- GAN FORMATION Raganelli, A.* - Wellmer, F. Smurfit Institute of Genetics Trinity College Dublin *Corresponding author e-mail: andrea.raganelli@gmail.com How complex organs are formed by multicellular organisms is a key question in developmental biology. Flower formation is an excellent system for studying the molecular mechanisms underlying organogenesis in plants. Several genes that control flower development have been identified in the model plant Arabidopsis thaliana but only few of them are known to specifically control the formation of the different types of floral organs, i.e.: sepals, petals, stamens and carpels. Most of these genes encode transcription factors or other proteins involved in the regulation of transcription, indicating the existence of a complex gene regulatory network that underlies flower development. Nevertheless, the target genes of the known transcriptional regulators, the regulatory elements, and how these genes interact is still for the most part unknown. We focus on the dissection of the genes network that underlies floral organ formation by the identification and functional characterization of target genes of key regulatory transcription factors at a global level. To this end, we are generating and testing different induction systems to separately control the onset of flowering with a floral induction system that allows the isolation of a large number of synchronized floral buds and the expression of artificial microRNAs (amiRNAs) directed against the transcription factor analyzed. This will enable us to specifically knock down the expression of floral regulators at different stages of flower development and through the use of genome-wide expression profiling by DNA microarray analysis, to identify the downstream responsive genes. P04-023: FUNCTIONAL STUDY OF TRANSCRIPTION FACTORS POTENTIALLY INVOLVED IN THE JUVENI- LE TO ADULT PHASE TRANSITION IN CITRUS Castillo, MC.¹* - Gas, M.E.² - Navarro, L.¹ - Ancillo, G.¹ ¹Instituto Valenciano Investigaciones Agrarias ²Institut de Génétique et de Biologie Moléculaire et Cellulaire *Corresponding author e-mail: mccastillo@ivia.es In higher plants, development has two different phases, juvenile and adult. Plants are not reproductively competent until they reach the adult phase. In citrus the juvenile phase can be as large as 5-20 years depending on the variety what is a serious constraint for molecular and conventional breeding of citrus genotypes. With the aim of identifying regulatory genes involved in the process of juvenile to adult phase transition we developed a citrus transcription factors (TF) microarray, and used it to screen for TF differentially expressed between juvenile and adult plants in four citrus species: Sweet Orange (C. sinensis (L.) Pineapple), Tangor Murcott (C. reticulata x C. sinensis), Grapefruit (C. paradisi Macf. Duncan) and Rough Lemon (C. limon (L.)). Several transcription factors were identified as differentially expressed. Some of these genes showed high homology with MADS-box genes which are a diverse class of TF that are involved in regulating developmental processes, particularly meristem and organ identity during floral development. On the other hand, some other genes showed no significant homology to genes of known function, indicating that they may be specific factors. Since the juvenility in citrus and Arabidopsis has differential aspects, those genes could be good candidates to study these particular aspects. To deep into their functional study, transgenic Arabidopsis lines over expressing some of these genes have been generated. Number of leaves without abaxial trichomes, flowering time and morphology of leaves, siliques and hole plant have been analysed. Some lines showed shortening of the juvenile phase, indicating that those genes are most likely involved in determining the reproductive phase transition in citrus. P04-024: STRUCTURE AND DNA BINDING SPECIFICI- TY OF THE LEAFY FLORAL TRANSCRIPTION FAC- TOR Moyroud, E. – Blanchet, S. – Minguet, E.G.* – Hames, C. – Thevenon, E. – Parcy, F. Physiologie Cellulaire Végétale. CNRS-INRA-CEA-UJF *Corresponding author e-mail: eugeniogomez@ono.com The LEAFY gene is present in all land plant and plays a central role in flower development of angiosperms [1]. It encodes a plant
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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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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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Book of Abstracts - Geyseco

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