Members at the University of Lausanne
Prof. John Pannell
Research in my lab is broadly centred on the areas of ecological genetics and plant evolutionary ecology. We are particularly interested in understanding
(1) plant gender and sex allocation strategies;
(2) the ecology, genetics and evolution of polyploidy, especially in its interaction with the sexual system;
(3) the evolution of local adaptation in colonising plant species; and
(4) the ecology and population genetics of metapopulations subject to repeated local extinctions and re-colonisations. A particular focus of much of this work is the evolution of combined (hermaphroditism) and separate sexes (dioecy), a contrast that implicates both the potential for inbreeding within populations as well as the extent to which plants specialize in one or other of their two genders.
Prof. Christian Fankhauser
Plant Photoreceptor-Mediated Signal Transduction
Both genetic and environmental factors influence growth and development of any living organism. Plant development is very plastic and is constantly modulated by environmental fluctuations. Being photoautotrophic plants are particularly sensitive to their light environment.Light affects all aspects of the plant life cycle. To optimize growth according to ambient light conditions plants evolved several classes of photoreceptors including the UV-A/blue light sensing cryptochromes and phototropins and the phytochromes maximally absorbing red/far-red light. The coordinated action of all these light receptors allows plants to fine-tune their development.
We focus our attention on two characteristic plant responses to light: phototropism which is the ability of plant stems to reorient their growth towards a unilateral source of light and shade avoidance which in shade intolerant plants such as Arabidopsis triggers elongation growth responses enabling the plant to reach unfiltered sunlight. Both light-responses contribute to the maximization of plant growth in particular in low light conditions that are typical in dense plant populations.
Prof. Edward Farmer
We work on the jasmonate pathway which controls plant immunity to herbivores. Jasmonates are lipid-derived molecules which accumulate rapidly when a plant is attacked or wounded. Our recent work has shown that the signal travelling from a wound to distal leaves has an average speed of about 4 cm per min. We have a second project on non-enzymatic lipid oxidation. We use Arabidopsis as a genetic tool to study this process and we concentrate on aspects that would be difficult to address in animals.
Prof. Christian Hardtke
A central feature of plant development is the post-embryonic formation of the majority of plant organs in a reiterative fashion. This build up of organs continues until the plant dies and can last hundreds of years in long-lived plants, like certain trees. Thus the control of plant growth and the elaboration of plant form are central to plant development.
Our research revolves around the genetic control of plant growth and development, and the underlying molecular mechanisms. We focus on genes that are responsible for modifying quantitative aspects of growth and morphology. We isolate such genes by exploiting natural genetic variation, for instance as observed in wild Arabidopsis thaliana strains. Arabidopsis is also our model of choice to characterize the cell biological and biochemical functions of the respective proteins. We are particularly interested in genes that determine the growth rate and architecture of the root system, as well as genes that determine the rate of secondary growth, i.e. the thickening of stems. We also investigate the molecular evolutionary aspects of those genes and in their role in other species, with a focus on the monocotyledon model, Brachypodium.
Dr. Christiane Nawrath
One of the important steps in the evolution of land plants is the formation of a primary barrier at the surface of aerial organs that limit the loss of water: the cuticle. The plant cuticle has evolved to a complex structure consisting of different lipid-derived compounds that plays a role in different aspects of plant biology ranging from stress protection to organ development. The research in our group is particularly directed on the elucidation of new components important for the formation of the cuticle and their significance for different cuticular functions. Arabidopsis thaliana is used as a model system for these studies.
Prof. Ian Sanders
Our work focuses on the mycorrhizal symbiosis between plants and arbuscular mycorrhizal (AM) fungi. The symbiosis occurs in the majority of terrestrial plant species. Through the effects of the fungus on plant phosphorus acquisition, plants benefit and can grow better when forming the symbiosis. The association is ancient and our group seeks to understand the genetics and evolution of these important fungi and how AM fungal genetics can influence plant growth. We have demonstrated three features of AM genetics that have important consequences for how plants grow. First, the fungi harbour genetically different nuclei in a common cytoplasm. Second, the fungi can fuse and the nuclei can mix giving rise to genetically novel AM fungi. Third, segregation of nuclei occurs during spore formation, giving rise to genetically different AM fungi. Both mixing of nuclei and segregation have important conseqences on the growth of rice. We manipulate the genetics of AM fungi using these processes to study which genes are affected in the plant by genetic changes in the fungus. These processes are natural and involve no gene insertion. A part of our work involves applying this technology to produce new strains of AM fungi for commerical inoculation of crops in Colombia (in collaboration with the National University of Colombia).
Prof. Niko Geldner
One of our main topics of interest is the study of endodermis as an invariant feature of vascular plants. It fulfils a crucial barrier function separating the extracellular space of outer cell layers from the inner apoplastic space of the vascular bundles. The "Casparian strip" has been defined as an area where endodermal cells secrete hydrophobic material in a highly localised and coordinated fashion to act as a barrier. The Casparian strip is composed of a ligno-suberic polymer, which forms an extensive, supra-cellular network. We demonstrate that there is no lateral diffusion across the Casparian Strip Domain (CSD) between outer and inner plasma membrane domains and we have identified transporters that localise to one or the other membrane region, depending on their function in uptake or efflux of nutrients. In addition we identified a new class of proteins that mark and predict the formation of the CSD. We will investigate the mechanisms underlying the formation of the Casparian Strip sub-domain on cellular surface and the localisation of proteins to either its central or peripheral side.
Prof. Pierre Goloubinoff
Our research is focused on molecular chaperones, proteins that assist the (un)folding of other proteins in the cell. Many molecular chaperones are stress-induced proteins. During and following stress, such as heat-shock, they are involved in the prevention of protein misfolding and aggregation in the cell. Hence, the chaperone network provides central mechanisms for the protection and the recovery from damaged proteins in prokaryotes and eukaryotes.
We are also interested in the mechanism for perception of heat-stress in plants. Plants need to rapidly detect mild temperature increments and develop thermotolerance by establishing appropriate molecular defenses against upcoming noxious temperatures. We found strong biochemical evidence that specific plasma membrane calcium channels act as the most upstream heat-sensors in the moss Physcomitrella patens. Currently, we are studying plant genes that are involved in the initial sensing of higher temperatures.
Our long-term goal is to understand heat-shock signaling and chaperone network, in order to prevent protein misfolding and promote the active curing of toxic protein aggregates, especially in the case of protein misfolding diseases.
Dr. Philippe Reymond
Molecular Studies of Plant-Insect Interactions
Plants attacked by insects develop an array of inducible defenses aimed at slowing the growth or development of the aggressor. We use genomics tools to monitor transcriptional changes in Arabidopsis after challenge with specialist (Pieris brassicae) or generalist (Spodoptera littoralis) leaf-chewing insects. Our research is mainly focused on two projects :
1) We want to know what are the insect-derived elicitors that trigger transcriptional reprogramming, which signals are involved in the transduction events and which transcription factors control defense gene induction after insect attack. The aim of this project to identify the genes that contribute to the plant resistance to herbivores.
2) Insect eggs deposited on a leaf represent a future threat as larvae hatching from the egg will ultimately feed on the plant. Eggs laid by Pieris brassicae modify the expression of hundreds of genes, indicating that plants are capable of detecting the presence of insect eggs and that they respond by activating defense gene expression. We want to identify the nature of egg-derived elicitor(s), the signaling pathways that control the oviposition-induced responses, and the benefits and costs of defense against oviposition.
Prof. Antoine Guisan
Spatial modelling of plant species distribution
• plant species – environment relationships
• environmental niche stability in space and time
• rare plant species modelling, model-based sampling,
• anticipating plant invasions, weed risk assessments
• climate threat to plant diversity, predicting range shifts and extinctions
• dispersal modelling and future plant migrations in fragmented landscapes
• assembling species predictions into communities, biotic interactions
• spatial modelling of functional and phylogenetic plant diversity
Prof. Yves Poirier
There are presently three main axes of research within our laboratory.
1. Metabolic pathways in the peroxisome and synthesis of polyhydroxyalkanoates
Our laboratory studies the pathways involved in fatty acid degradation in the peroxisomes of fungi and plants using a novel tool that we have developed, namely the synthesis of the biopolyester polyhydroxyalkanoate from the polymerization of the intermediates of the ß-oxidation cycle.
2. Study of the isoprenoid pathway
Plants synthesize a wide diversity of molecules from the isoprenoid pathway. Of particular interest to our group is the synthesis of rubber and how the carbon flux through the isoprenoid pathway can be modulated to increase rubber biosynthesis.
3. Phosphate transport and metabolism
Inorganic phosphate (Pi) is one of the main nutrients limiting the growth. Our work on Pi transport and metabolism is focused on the characterization of the PHO1 gene family in Arabidopsis and rice. The PHO1 gene is involved in the loading of Pi from the root into the xylem vessels. A family of 10 genes related to PHO1 have recently been identified from the Arabidopsis genome project. Our main goal is to gain a comprehensive view of the role of these genes in phosphate acquisition and distribution throughout the plant.