Seminararchiv

Many plant species display remarkable developmental plasticity and regenerate new organs after injury. Local signals produced by wounding are thought to trigger organ regeneration but molecular mechanisms underlying this control remain largely unknown^1,2. We have previously identified a group of AP2/ERF transcription factors named WOUND INDUCED DEDIFFERENTIATION1-4 (WIND1-4) as central regulators of wound-induced cellular reprogramming in plants³. More recently we demonstrated that WIND1 promotes shoot regeneration by directly up-regulating ENHANCER OF SHOOT REGENERATION1 (ESR1) encoding another AP2/ERF transcription factor in Arabidopsis⁴. We have also shown that some of WIND genes and other developmental regulators need to be epigenetically repressed by POLYCOMB REPRESSIVE COMPLEX 2 to prevent unscheduled cellular reprogramming in intact plants^5,6. In this talk I will discuss our latest findings on how WIND proteins promote cellular reprogramming and how wound stress activates the WIND-mediated pathway by overriding epigenetic repression. [mehr]

Sandra Kerbler - Unravelling the mitochondrial electron transport chain in the cold: is ATP synthase the key?

Datum: 17.03.2017
Uhrzeit: 14:00 - 15:30
Vortragende(r): Sandra Kerbler
PLANT ENERGY BIOLOGY UNIVERSITY OF WESTERN AUSTRALIA, Perth, Australia
Ort: Box
Raum: 0.21
Gastgeber: Mark Stitt

[mehr]

Siobhan M. Brady - Transcriptional regulation of plant metabolism

Datum: 08.02.2017
Uhrzeit: 14:00 - 15:30
Vortragende(r): Siobhan M. Brady
Section of Plant Biology and Genome Center, University of California, USA
Ort: Central Building
Raum: Seminar Room
Gastgeber: Mark Stitt

Regulation of plant development requires intricate communication with both primary and specialized metabolism in order to fuel growth. While transcriptional regulation of metabolism is evident from myriad whole genome-expression analyses, our understanding of which transcriptional regulators are responsible for these changes as well as their underlying mode of action is unclear. I will highlight our efforts on systematic mapping of transcriptional regulators of nitrogen metabolism, the tricarboxylic acid cycle and glucosinolate biosynthesis. Network analyses incorporating protein-DNA interaction data, gene expression and connectivity were used to identify critical regulators, most of which were shown to regulate growth and metabolism in planta. Finally, these analyses have shed light on modularity within these pathways and global perspectives on this additional mode of plant metabolic regulation. [mehr]

Marja Timmermans - Small RNAs as mobile, morphogen-like signals in development

Datum: 25.01.2017
Uhrzeit: 14:00 - 15:30
Vortragende(r): Marja Timmermans
ZMBP Developmental Genetics and Cell Biology, University of Tuebingen, Germany
Ort: Central Building
Raum: Seminar Room
Gastgeber: Mark Stitt

Abstract: Small RNAs as mobile, morphogen-like signals in development Damianos Skopelitis¹, Anna Benkovics¹, Aman Husbands¹ and Marja Timmermans^1,2 ¹⁾ Cold Spring Harbor Laboratory, 1 Bungtown Rd, Cold Spring Harbor, NY 11724, USA ²⁾ Center for Plant Molecular Biology, University of Tuebingen, Auf der Morgenstelle 32, 72076 Tuebingen, Germany Adaxial-abaxial (top-bottom) polarity drives the flattened outgrowth and patterning of leaves, and represents an important innovation in the evolution of land plants. Patterning of this axis is driven by an intricate gene regulatory network. Integral to this network are two sets of conserved transcription factors that promote either adaxial or abaxial fate, and are expressed in complementary domains on the top or bottom side of the leaf, respectively. The positional information needed to delineate these domains is provided in part by the small RNAs miR166 and tasiR-ARF. We have shown that these small RNAs move outside their defined domain of biogenesis and form opposing gradients across the leaf that polarize expression of key adaxial- and abaxial-promoting transcription factors, HD-ZIPIII and ARF3/4, respectively. Our observations, which will be presented, indicate that mobile small RNAs have the inherent capacity to generate sharp gene expression boundaries, and function as morphogen-like signals in development. Their patterning properties present small RNAs and their targets as highly portable regulatory modules through which to create pattern, and provides a compelling basis for the extensive conservation and repeated co-option of developmentally important small RNA-target modules. [mehr]

Jenny Russinova - Trafficking of Plant Receptor Kinases: When the Intracellular Logistics Matters

Datum: 30.11.2016
Uhrzeit: 14:00 - 15:30
Vortragende(r): Jenny Russinova
Department of Plant Systems Biology, VIB, Department of Plant Biotechnology and Bioinformatics, Ghent University, Belgium
Ort: Central Building
Raum: Seminar Room
Gastgeber: Mark Stitt

Abstract: Receptor-mediated endocytosis is an integral part of signal transduction, as besides signal attenuation, by removal of activated receptors and their bound ligands from the cell surface, it allows the spatial and temporal regulation of the signaling outputs from the endosomes. After receptors have been activated and internalized, they can be separated from their ligands and recycled back to the plasma membrane or transported for degradation. Crucial in the study of the interplay between endocytosis, recycling, and signaling of plant receptor kinases is the development of imaging tools (bioactive fluorescent probes) to visualize membrane-associated signaling events at a high spatiotemporal resolution. Recently, we have been able to view endocytosis of different receptor kinases in living Arabidopsis thaliana cells using fluorescent small-molecule and peptide ligands. In addition, we are exploring the chemical biology for development of novel specific endocytosis inhibitors that will contribute to the better understanding of how this process regulates signaling outputs in plants. [mehr]

Gary Stacey - Application of soybean genomic tools to the study of the nitrogen fixing, rhizobium symbiosis

Datum: 09.11.2016
Uhrzeit: 14:00 - 15:30
Vortragende(r): Gary Stacey
Division of Plant Sciences and Biochemistry, University of Missouri, USA
Ort: Central Building
Raum: Seminar Room
Gastgeber: Mark Stitt

The successful completion of the soybean genome sequence in 2010 enabled the application of the full range of genomic tools and methods to the study of the nitrogen fixing rhizobial symbiosis. This symbiosis is the result of infection of soybean roots by the soil bacterium, Bradyrhizobium japonicum. In order to more precisely study the early infection events during the establishment of this symbiosis, my laboratory pioneered the use of isolated root hair cells as a single cell model for systems biology. We have applied the full repertoire of functional genomic methods to this system characterizing, for example, the transcriptome, proteome, phosphoproteome, miRNA, DNA methylation, and others. These studies, within the context of a general focus on soybean genomics, has enabled us to compile a large dataset, which has provided novel insight into the mechanisms by which the nitrogen fixing symbiosis is established. Among these important insights is the growing realization that the plant innate immunity system plays an important role in the symbiosis. [mehr]

Lukas M. Müller - The sucrose storage metabolism regulates carbohydrate supply for growth by a concentration-dependent kinetics but not the circadian clock in barley

Datum: 28.10.2016
Uhrzeit: 10:45 - 12:15
Vortragende(r): Lukas M. Müller
Institute of Plant Genetics, Heinrich Heine University, Düsseldorf & Max Planck Institute for Plant Breeding Research, Department of Plant Developmental Biology, Cologne, Germany
Ort: Box
Raum: 0.21
Gastgeber: Mark Stitt

The circadian clock controlscarbohydrate metabolism and growth in Arabidopsis, suggesting it as key targetfor crop improvement. However, my recent work shows that the circadian clockthrough EARLY FLOWERING 3 (ELF3) does not determine carbohydrate supply forgrowth in barley at night, in contrast to Arabidopsis. I find that carbohydratesupply from the leaves at night is dominated by sucrose in barley but notstarch as in Arabidopsis. Depletion of transitory sucrose from the leaf wasexponential and almost exhausted at the end of the night, even under unexpectedextension of photoperiod. This depletion pattern depended on the sucrosecontent at the end of the day, was independent from circadian control andpresumably determined by SUCROSE TRANSPORTER 2 (SUT2) through catalyzingsucrose export from the vacuole by a kinetics of first order. On the otherhand, degradation of the little amounts of transitory starch in barley wastemporally controlled by the clock component ELF3 in both barley and Arabidopsis.Therefore, barley and Arabidopsis apply two different forms of nocturnalcarbohydrate supply: The sucrose storage and the starch storage metabolism.Consistent with regulation by a clock-driven program or a transporter-catalyzedkinetic, carbohydrate supply from starch was compensated against lowtemperature while reduced for sucrose so that barley, but not Arabidopsis,reduced biomass after growth in cool nights. Growth of wheat, rice and wildbarley but not Brachypodium also depended on the sucrose storage metabolism. Insummary, my findings explain how cool nights and the circadian clock determinegrowth in different species despite the conservation of the circadian clock. [mehr]

Steven Kelly - Necessity is the mother of re-invention: linking parallel evolution of genes and genomes to the evolution of complex traits

Datum: 30.03.2016
Uhrzeit: 14:00 - 15:30
Vortragende(r): Steven Kelly
Ort: Central Building
Raum: Seminar Room
Gastgeber: Mark Stitt

Much of biology is associated with the evolution of convergent traits. For example the eyes of squids and squirrels have evolved independently by harnessing the same genes and developmental pathways. However convergent evolution also occurs at smaller scales and can be seen in thousands of examples of how organisms adapt their genes and genomes to respond to the shared challenges of survival. In this talk I will discuss how studying the parallel evolution of new genes has provided new insight into the evolution of C4 photosynthesis. I will then discuss how adaptation to changes in metabolism can drive the parallel evolution of genomes. [mehr]

Translational Dynamics in the Arabidopsis Seed

Datum: 07.12.2015
Uhrzeit: 13:00 - 14:30
Vortragende(r): Johannes Hanson
Ort: Central Building
Raum: Seminar Room
Gastgeber: Mark Stitt

Seeds are unique living structures that survive being dried to less than 5% water content and are revitalized during germination. Protein translation is required during the early stages of germination prior the need of transcription. Genome-wide profiling of the total mRNA and polysome associated mRNA pools of Arabidopsis seeds identified extensive translation regulation in seeds, specifically during germination. The mechanism and possible relevance of these novel regulatory patterns in seed physiology will be discussed. [mehr]

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