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Plant Systems Biology, VIB2, Meetings & Seminars
Plant Systems Biology
PSBUgent
Our department actively seeks to invite high-profile researchers to give talks on various subjects in the field of Plant Systems Biology. Check our website for general contact or directions.
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1 September 2010 - 30 September 2010
Sep 6Mon"SCI1, A TISSUE-SPECIFIC CELL CYCLE REGULATOR THAT CONTROLS STIGMA/STYLE DEVELOPMENT"

ABSTRACT
The success of plant reproduction depends on the appropriate development of the reproductive organs, which involves general and specific regulatory networks. We have characterized a gene, SCI1 (stigma/style cell cycle inhibitor 1), encoding a nuclear small lysine-rich protein that exerts an inhibitory action on cell cycle. qRT-PCR and in situ hybridization experiments showed that SCI1 is stigma/style-specific and developmentally regulated. SCI1 RNAi knockdown and overexpression transgenic plants exhibited stigmas/styles with remarkably enlarged and reduced areas, respectively, due to differences in cell numbers. Alterations on SCI1 expression affected cell divisions on the stigmatic secretory zone (SSZ) and the differentiation timing of the papillar cells. Taken together, our results reveal that SCI1 is a novel tissue-specific negative cell cycle regulator that couples stigma cell division and differentiation. Additionally, two-hybrid and BiFC experiments showed that SCI1 interacts with A-type cyclins. We conclude that SCI1 represents a novel developmentally regulated tissue-specific gene that controls cell proliferation/differentiation, probably as a component of a signaling pathway involved in upper pistil development.
Sep 21Tue"Metabolomics from fundamental understanding to marker-assisted breeding"

ABSTRACT
Metabolomics approaches enable the parallel assessment of the levels of a broad range of metabolites and have been documented to have great value in both phenotyping and diagnostic analyses in plants. These tools have recently been turned to evaluation of the natural variance apparent in metabolite composition. Here, I will describe exciting progress made in the identification of the genetic determinants of crop plant chemical composition, focussing on the application of metabolomics strategies and their integration with other high-throughput technologies. The Zamir Solanum pennellii introgression lines will be used as a case study and I will illustrate the value of this approach by demonstrating a few examples whereby we have been able to identify the genetic factors underlying important agronomic and nutritional traits. Whilst work in this area is currently carried out at the level of fundamental science I will conclude with an outlook of my personal perspective of its applied uses.
"Metabolic response to oxidative stress in Arabidopsis"

ABSTRACT
Plants must reconfigure their metabolic network under stress conditions to prevent the accumulation of reactive oxygen species (ROS) and to produce indispensable metabolites. We have investigated the response of Arabidopsis roots to menadione-induced oxidative stress by means of metabolite profiling and transcriptome analysis. The results suggested the importance of mitochondrial metabolism in stress response and also highlighted a complex relationship between the levels of transcripts, metabolites, and metabolic flux. We hypothesise the reassembly of enzyme protein complexes as a molecular mechanism of mitochondrial metabolic regulation. A proteomic approach using blue-native/SDS-PAGE revealed that some mitochondrial enzymes associated to or dissociated from a protein complex under oxidative stress. These results suggest the regulation of the TCA cycle, glycolysis, ascorbate and amino acid metabolism under oxidative stress by reassembly of enzyme supercomplexes.
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1 October 2010 - 31 October 2010
Oct 12Tue"Plant immunity: it’s the hormones talking, but what do they say?"

ABSTRACT
Plants live in complex environments in which they intimately interact with a broad range of other organisms. Besides the plethora of deleterious interactions with pathogens and insect herbivores, relationships with beneficial microorganisms are frequent in nature as well, improving plant growth or helping the plant to overcome stress. The evolutionary arms race between plants and their enemies provided plants with a highly sophisticated defense system that, like the animal innate immune system, recognizes non-self molecules or signals from injured cells, and responds by activating an effective immune response against the invader encountered. Recent advances in plant immunity research underpin the pivotal role of cross-communicating hormones in the regulation of the plant’s defense signaling network. Their powerful regulatory potential allows the plant to quickly adapt to its hostile environment and to utilize its resources in a cost-efficient manner. Plant enemies on the other hand, can hijack the plant’s defense signaling network for their own benefit by affecting hormone homeostasis to antagonize the host immune response. Similarly, beneficial microbes actively interfere with hormone-regulated immune responses to avoid being recognized as an alien organism. In nature, plants simultaneously or sequentially interact with multiple beneficial and antagonistic organisms with very different lifestyles. However, knowledge on how the hormone-regulated plant immune signaling network functions during multi-species interactions is still in its infancy. In the past years, various genomics approaches expanded our understanding of the molecular mechanisms by which plants tailor their defense response to pathogen and insect attack. Diverse hormones such as salicylic acid (SA), jasmonic acid (JA) and ethylene (ET) play pivotal roles in the regulation of the defense signaling network. Our research is focused on the molecular interplay between these hormones and how their interactions steer the final outcome of the plant immune response.
Oct 25Mon"How plants survive the night"

ABSTRACT
Although plants make sugars from atmospheric carbon dioxide in the process of photosynthesis, they face problems of carbohydrate supply on a daily basis. First, most of the cells in a plant are heterotrophic – dependent for their carbon supply on carbohydrate (in the form of sucrose) imported from the relatively small number of photosynthetic cells in the leaves. Second, plants can photosynthesise only during the day - every night all of the cells of the plant become dependent upon the mobilisation of carbohydrate (in the form of starch) synthesised and stored during the day. Mutant plants that cannot synthesise starch during the day or cannot degrade it at night usually have reduced growth rates. 
My lab is trying to understand the diurnal control of starch storage and mobilisation in leaves of the model plant Arabidopsis, using forward and reverse genetic approaches. I will present our progress in defining the surprisingly complex pathway of starch degradation at night, and discuss how flux through this pathway is controlled to ensure that supplies of carbohydrate last until dawn. Our recent work shows that the circadian clock plays a central role in controlling carbohydrate availability at night, and this in turn determines the overall productivity of the plant. Finally I will describe unexpected findings about the ways in which non-photosynthetic cells mobilise the sucrose they receive from the leaves.
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