|comité de direction|
|morphogenèse, signalisation, modélisation|
|dynamique et expression des génomes|
|adaptation des plantes à leur environnement|
|reproduction et graines|
|paroi végétale, fonction et usage|
The First Symposium
IJPB will offer a chance to listen to some of the best research developed
at IJPB (but only a fraction of it!) with talks from David
Corine Enard (Institut Jean-Pierre Bourgin (IJPB), Versailles),
Lacruz (IJPB, Versailles), Philippe Poré (INRA, Versailles)
Raude (IJPB, Versailles)
Mitochondria serve as principal sites for cellular energy metabolism and play pivotal roles in the biosynthesis of many essential metabolites for the (plant) cell. As dependences of a free-living organism, mitochondria contain their own genome, the mtDNA. The mtDNAs in plants are notably larger and more complex in structure than their corresponding ones in Animalia. Plant mitochondria are also remarkable with respect to the presence of numerous group II introns that reside in many organellar genes. The removal of the introns from the coding sequences they interrupt is essential for respiratory functions and is mediated by enzymes that belong to a diverse set of protein-families. These include intron-encoded related proteins (i.e. maturases) that function in the splicing of group II introns in bacteria and mitochondria in fungi and plants, usually with high specificity towards the intron in which they are encoded. While the splicing of group II introns in vivo is facilitated by maturase factors, canonical group II introns are catalytic RNAs that are able to excise themselves from their pre-RNA hosts in vitro, in the absence of the protein cofactors, using a mechanism identical to that utilized by the spliceosome. Structural analyses and phylogenetic data may indicate that the spliceosomal RNAs have evolved from group II intron-related ancestors. Yet, it remains unclear how could such general players in spliceosomal splicing evolve from the monospecific bacterial systems (i.e. a group II intron RNAs and their highly specific intron-encoded maturase factors). Analysis of the organellar splicing machinery in plants may provide us with important clues into the evolution of the nuclear splicing machineries. Genetic and biochemical studies led to the identification of different protein factors that facilitate the splicing of many of the mitochondrial introns in plants. We established the native RNA targets of different maturase factors in plants and analyzed the organellar and developmental defects associated with their mutant lines in vivo. Interestingly, while model maturases in bacteria and fungi mitochondria act specifically on their cognate intron RNAs, the plant maturases are acting on multiple mtRNA targets, thus seem to be acting as organellar proto-spliceosomal factors. The ability of the mitochondrial maturases in plants to act on different intron targets further support the notion that the early organellar self-splicing and mobile group II RNAs spread in the eukaryotic genomes and later ‘degenerated’ into the universal splicing system, known as the spliceosome. The similarities between maturases and the core spliceosomal factor, Prp8, may support this intriguing hypothesis.
Invited by: Hakim Mireau
Invited by: Céline Masclaux-Daubresse
Invited by: Herman Höfte
Plant shoots harbor stem cells throughout the life of the plant maintained via a gene regulatory feedback network. Perturbations to these regulatory genes lead to changes in the size and shape of the stem cell niche. Similar effects can be achieved by perturbing the cell walls and heterogeneous and anisotropic mechanical wall properties need to be regulated to generate correct form. We use a Computational Morphodynamics approach, combining live imaging and models of cell wall mechanics and gene networks, to understand how growth and differentiation is coordinated. In this talk I will discuss how mechanical patterning can overlap with gene expression patterns, and how cell size and tissue size can influence the maintenance of the stem cell niche.
Invited by: Jasmine Burguet & Philippe Andrey
In plants, alterations of reactive oxygen species (ROS) levels cause fluctuations of the redox balance and hence can affect many aspects of cellular physiology. ROS levels are controlled by a diversified set of antioxidant systems that allow the maintenance of redox status. Perturbations of these ROS levels can lead to transient or permanent changes in the redox status. This feature is exploited by plants in different stress signaling mechanisms. Understanding how plants sense ROS and transduce these stimuli into downstream biological responses is still a major challenge. Previous transcriptome-centered analyses, provided us first insights in the regulatory networks that govern the oxidative stress response. Now, tailoring various proteomics technologies allowed us to assess oxidative stress dependent changes at the posttranslational level. These efforts will allow a better understanding of how cells interpret the oxidative signals that arise from developmental cues and stress conditions.
Van Breusegem Lab
is critical for multicellularity. It coordinates the activities
within individual cells to support the function of an
organism as a whole. Plants have developed remarkable
cellular machines -the Plasmodesmata (PD) pores- which
interconnect every single cell within the plant body,
establishing direct membrane and cytoplasmic continuity,
a situation unique to plants. PD are indispensable for
plant life. They control the flux of molecules between
cells and are decisive for development, environmental
adaptation and defence signalling. However, how PD integrate
signalling to coordinate responses at a multicellular
level remains unclear.
During the past years,
great progress has been made in the development of association
methods for GWAS or QTL mapping. However, methods to map
the variation that can be found between species are still
sparse. We have developed a genomics-based method for
between-species (or ‘phylogenetic’) association
mapping (PAM), which can find signals even in highly re-arranged
genomes of different species. In my presentation, I will
show how we used PAM in a panel of 47 closely-related
plant species to map the genetic underpinnings of differences
in the mutational profiles that we found in these species.
Schneeberger groupe webpage
Forests assimilate approximately a quarter of the annual anthropogenic CO2 emissions. Most of this carbon is incorporated to wood which, together with the topsoil-bound carbon, create the main long-term terrestrial carbon sink on the planet. The majority of the woody biomass resides in the cell walls of wood fibres. Carbon for the fiber walls is derived from sucrose, which is synthesized and transported from photosynthetic tissues. Sucrose is actively imported into developing wood fibers, and once in the cytosol sucrose hydrolysis is carried out either by invertase (INV) or sucrose synthase (SUS) activity to provide carbon and energy for cell wall biosynthesis. In this talk I will present our work on understanding the structure and regulation of the metabolic pathways responsible for carbon transport and incorporation into wood. This will include our recent finding placing the little studied cytosolic INVs in a central position in wood metabolism and cellulose biosynthesis, a concept of altering cellulose microfibril properties by modifying substrate supply to cellulose biosynthesis, and recent results on the composition of cellulose synthase complex in the developing wood of aspen.
Autophagy is an evolutionary conserved process involved in maintaining cellular homeostasis via controlled degradation of cellular components and nutrients recycling. It is negatively regulated by the TOR (Target of Rapamycin) kinase complex, a central regulator of cellular metabolism. In plants, the process of autophagy is important in normal development as well as during various environmental stresses. Autophagy is not just a bulk degradation of cellular content but it can be highly selective due to involvement of proteins called selective autophagy cargo receptors that are able to recognize and target the autophagy cargo to the double-membrane vesicles called autophagosomes. The autophagosomes are delivered to the vacuole for degradation. Not only cargo but also the cargo receptors are degraded during this process. The first plant selective autophagy cargo receptors from the NBR1-family have been described in 2011 by two independent groups. The talk will cover data related to identification and characterization of NBR1-like proteins in plants. Next I will focus on the consequences of NBR1 overexpression in plants and discuss the links between NBR1 activity, autophagy flux and TOR signaling pathway.
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