- Seminars - maillist.psb.ugent.be

PSB event reminder
by contact＠psb.vib-ugent.be 10 Oct '11

10 Oct '11

Calendar Name: seminars Scheduled for: Monday, October 10 2011, 11:00 - 12:30 Event text: Prof Zhenbiao Yang Center for Plant Cell Biology Department of Botany and Plant Sciences University of California Riverside USA Details: �Auxin regulates pattern formation in a self-organizing and hierarchical manner in the Arabidopsis leaf epidermis� ABSTRACT Auxin regulates the formation of various developmental and morphogenetic patterns in plants, but the molecular and cellular mechanisms for the auxin actions are not well understood. We investigate these mechanisms using Arabidopsis leaf epidermal pavement cells (PCs) as a model system, which form the jigsaw puzzle cell pattern with interdigitated lobes and indentation. We have shown that pavement cell interdigitation is controlled by localized ROP GTPase signaling, which impinges on the organization of cortical actin microfilaments and microtubules to generate interdigitating lobes and indentations1,2. Our recent studies indicate that auxin is a localized signal that activates pavement cell polarization to form lobes and coordinates lobe formation with indentation formation by activating ROP GTPase signaling through an Auxin-Binding Protein 1 (ABP1) dependent auxin perception system3. This cytoplasmic auxin signaling system, which is distinct from the well-established TIR1-dependent nuclear auxin signaling system that regulates gene transcription, modulates local coordination of lobe and indentation formation within a PC and between adjacent PCs through its modulation of PIN protein polarization3. Our recent work suggests that auxin also globally coordinates the formation of the interdigitated PC pattern in the entire leaf through a transient leaf tip- and margin-high accumulation of auxin. The global coordination and the auxin accumulation require the TIR1-based auxin-signaling pathway that regulates gene transcription. Our findings support the hypothesis that auxin acts as a self-organizing and hierarchical signal in the regulation of pattern formation in the leaf epidermis. References 1. Fu, Y., Y. Gu, Z. Zheng, G. Wasteneys, and Z. Yang. 2005. Arabidopsis interdigitating cell growth requires two antagonistic pathways with opposing action on cell morphogenesis. Cell 120: 687-700. 2. Fu, Y., T. Xu, L. Zhu, and Z. Yang. 2009. A ROP GTPase signaling pathway controls microtubule ordering and cell expansion in Arabidopsis. Curr. Biol. 19:1827-32. 3. Xu T, Wen M, Nagawa S, Fu Y, Chen JG, Wu MJ, Perrot-Rechenmann C, Friml J, Jones AM, Yang Z. 2010. Cell surface- and rho GTPase-based auxin signaling controls cellular interdigitation in Arabidopsis. Cell 143:99-110.

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PSB event reminder
by contact＠psb.vib-ugent.be 08 Oct '11

08 Oct '11

Calendar Name: seminars Scheduled for: Monday, October 10 2011, 11:00 - 12:30 Event text: Prof Zhenbiao Yang Center for Plant Cell Biology Department of Botany and Plant Sciences University of California Riverside USA Details: �Auxin regulates pattern formation in a self-organizing and hierarchical manner in the Arabidopsis leaf epidermis� ABSTRACT Auxin regulates the formation of various developmental and morphogenetic patterns in plants, but the molecular and cellular mechanisms for the auxin actions are not well understood. We investigate these mechanisms using Arabidopsis leaf epidermal pavement cells (PCs) as a model system, which form the jigsaw puzzle cell pattern with interdigitated lobes and indentation. We have shown that pavement cell interdigitation is controlled by localized ROP GTPase signaling, which impinges on the organization of cortical actin microfilaments and microtubules to generate interdigitating lobes and indentations1,2. Our recent studies indicate that auxin is a localized signal that activates pavement cell polarization to form lobes and coordinates lobe formation with indentation formation by activating ROP GTPase signaling through an Auxin-Binding Protein 1 (ABP1) dependent auxin perception system3. This cytoplasmic auxin signaling system, which is distinct from the well-established TIR1-dependent nuclear auxin signaling system that regulates gene transcription, modulates local coordination of lobe and indentation formation within a PC and between adjacent PCs through its modulation of PIN protein polarization3. Our recent work suggests that auxin also globally coordinates the formation of the interdigitated PC pattern in the entire leaf through a transient leaf tip- and margin-high accumulation of auxin. The global coordination and the auxin accumulation require the TIR1-based auxin-signaling pathway that regulates gene transcription. Our findings support the hypothesis that auxin acts as a self-organizing and hierarchical signal in the regulation of pattern formation in the leaf epidermis. References 1. Fu, Y., Y. Gu, Z. Zheng, G. Wasteneys, and Z. Yang. 2005. Arabidopsis interdigitating cell growth requires two antagonistic pathways with opposing action on cell morphogenesis. Cell 120: 687-700. 2. Fu, Y., T. Xu, L. Zhu, and Z. Yang. 2009. A ROP GTPase signaling pathway controls microtubule ordering and cell expansion in Arabidopsis. Curr. Biol. 19:1827-32. 3. Xu T, Wen M, Nagawa S, Fu Y, Chen JG, Wu MJ, Perrot-Rechenmann C, Friml J, Jones AM, Yang Z. 2010. Cell surface- and rho GTPase-based auxin signaling controls cellular interdigitation in Arabidopsis. Cell 143:99-110.

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Seminar Prof Zhenbiao Yang
by Delphine Verspeel 04 Oct '11

04 Oct '11

You are receiving this e-mail because you subscribed to our seminars announcements and reminders service at <https://maillist.psb.ugent.be/mailman/listinfo/seminars> https://maillist.psb.ugent.be/mailman/listinfo/seminars. If you do not wish to receive this information anymore, please unsubscribe from future mailings at <https://maillist.psb.ugent.be/mailman/options/seminars> https://maillist.psb.ugent.be/mailman/options/seminars. cid:946540515@15122008-0D1C PSB cid:946540515@15122008-0D23 VIB - Department of Plant Systems Biology Technologiepark 927 B - 9052 Gent/Zwijnaarde Phone: +32 9 33 13 800 Fax: +32 9 33 13 809 Http://www.psb.vib-ugent.be

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PSB event reminder
by contact＠psb.vib-ugent.be 03 Oct '11

03 Oct '11

Calendar Name: seminars Scheduled for: Monday, October 3 2011, 11:00 - 12:30 Event text: Dr Arthur Korte Gregor Mendel Institute of Molecular Plant Biology Vienna AUSTRIA Details: �Combining multiple traits for Genome-wide association mapping� ABSTRACT Genome-wide association studies (GWAS) have become an obvious general approach for studying the genetics of natural variation. Although a plethora of significant associations of SNPs with different traits have been recently described (some of which have already been verified experimentally), these analyses have been focused on the identification of associations within a single trait. When inbred lines are available, it is possible to study many different traits for the same genotype under different experimentally conditions. An obvious next step is to derive a GWAS model that enables the joint analysis of different traits, while accounting for population structure. Hence we derived an extended version of the broadly used mixed model and validated our statistical model through simulations. We could verify that our model both increase the power to identify new SNPs and control the false discovery rate. Due to the simultaneous testing of both the gene and the gene-environment effect in the model we can identify both, SNPs that are globally important in both traits (not influenced by the environment) and SNPs important for gene-environment interaction (having different effects in the respective trait(s)). This method opens the possibility to simultaneously analyze related traits and gain insights into their underlying genetic architecture. Applying the model on real data leads to the identification of novel associations, which were not identified by the marginal analysis

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PSB event reminder
by contact＠psb.vib-ugent.be 01 Oct '11

01 Oct '11

Calendar Name: seminars Scheduled for: Monday, October 3 2011, 11:00 - 12:30 Event text: Dr Arthur Korte Gregor Mendel Institute of Molecular Plant Biology Vienna AUSTRIA Details: �Combining multiple traits for Genome-wide association mapping� ABSTRACT Genome-wide association studies (GWAS) have become an obvious general approach for studying the genetics of natural variation. Although a plethora of significant associations of SNPs with different traits have been recently described (some of which have already been verified experimentally), these analyses have been focused on the identification of associations within a single trait. When inbred lines are available, it is possible to study many different traits for the same genotype under different experimentally conditions. An obvious next step is to derive a GWAS model that enables the joint analysis of different traits, while accounting for population structure. Hence we derived an extended version of the broadly used mixed model and validated our statistical model through simulations. We could verify that our model both increase the power to identify new SNPs and control the false discovery rate. Due to the simultaneous testing of both the gene and the gene-environment effect in the model we can identify both, SNPs that are globally important in both traits (not influenced by the environment) and SNPs important for gene-environment interaction (having different effects in the respective trait(s)). This method opens the possibility to simultaneously analyze related traits and gain insights into their underlying genetic architecture. Applying the model on real data leads to the identification of novel associations, which were not identified by the marginal analysis

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FW: Upcoming seminars October
by Delphine Verspeel 28 Sep '11

28 Sep '11

Dear all, Enclosed the updated list for October. Kind regards, Delphine From: Delphine Verspeel [mailto:despe@psb.ugent.be] Sent: maandag 26 september 2011 15:48 To: 'meetings(a)psb.vib-ugent.be' Subject: Upcoming seminars October Dear all, Enclosed you can find our upcoming seminars for October. Kind regards, Delphine ____________________________________________ Delphine Verspeel Administrative Assistant VIB, Department of Plant Systems Biology Ghent University Technologiepark 927 9052 Gent Belgium Phone: +32/9/33.13.800 Fax: +32/33.13.809 Http://www.psb.ugent.be despe(a)psb.vib-ugent.be <mailto:nahau@psb.vib-ugent.be>

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Seminar Dr Arthur Korte 03/10
by Delphine Verspeel 26 Sep '11

26 Sep '11

You are receiving this e-mail because you subscribed to our seminars announcements and reminders service at <https://maillist.psb.ugent.be/mailman/listinfo/seminars> https://maillist.psb.ugent.be/mailman/listinfo/seminars. If you do not wish to receive this information anymore, please unsubscribe from future mailings at <https://maillist.psb.ugent.be/mailman/options/seminars> https://maillist.psb.ugent.be/mailman/options/seminars. cid:946540515@15122008-0D1C PSB cid:946540515@15122008-0D23 VIB - Department of Plant Systems Biology Technologiepark 927 B - 9052 Gent/Zwijnaarde Phone: +32 9 33 13 800 Fax: +32 9 33 13 809 Http://www.psb.vib-ugent.be

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Upcoming seminars October
by Delphine Verspeel 26 Sep '11

26 Sep '11

Dear all, Enclosed you can find our upcoming seminars for October. Kind regards, Delphine ____________________________________________ Delphine Verspeel Administrative Assistant VIB, Department of Plant Systems Biology Ghent University Technologiepark 927 9052 Gent Belgium Phone: +32/9/33.13.800 Fax: +32/33.13.809 <Http://www.psb.ugent.be> Http://www.psb.ugent.be <mailto:nahau@psb.vib-ugent.be> despe(a)psb.vib-ugent.be

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Seminar Bruno Cammue 27/09/11: CANCELLED
by Christine Tire 23 Sep '11

23 Sep '11

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PSB event reminder
by contact＠psb.vib-ugent.be 22 Sep '11

22 Sep '11

Calendar Name: seminars Scheduled for: Thursday, September 22 2011, 11:00 - 12:30 Event text: Prof Tom Beeckman VIB, Dept. of Plant Systems Biology Ghent University Gent BELGIUM Details: "Root branching controlled by the tips" ABSTRACT In the root, branching, i.e. de novo organogenesis or formation of lateral roots, is known to occur outside the apical meristem in a distinct monolayer of cells, designated as the pericycle. Not every pericycle cell becomes implicated into lateral root formation and it has been proposed that an auxin-dependent signaling mechanism will result in the specification of some cells as �founder cells�. Founder cell specification is not a continuous process but presents an oscillatory appearance that is proposed to be determinative for the longitudinal spacing of lateral roots along the primary root. However, the molecular mechanisms driving the periodical specification of founder cells remain largely elusive. Through a targeted transcript profiling approach, the Root Development group in Gent (Belgium) has obtained new insights into this very early step of lateral root formation. Our results support a hypothesis in which multiple tissue-specific successive auxin signaling modules are involved during the entire process of lateral root formation. The earliest auxin signaling module is situated in the root apex in proximity of the root apical meristem. Furthermore, a chemical compound screening unmasked the importance of precursor-to-auxin conversion activities in the very root tip. In summary, the root tip is a crucial activity centre that has a decisive role on the way roots colonize the surrounding soil.

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