1. Signaling of induced responses to herbivores
Transcriptional patterns elicited in response to attack reveal, at the molecular level, how plants respond to aggressors. We study the interaction between Arabidopsis thaliana and larvae of specialist (Pieris rapae) or generalist (Spodoptera littoralis) chewing herbivores. We would like to know which insect-derived elicitors trigger changes in gene expression, which signals are involved in transduction events and which genes are induced after insect attack. For that purpose we employ Arabidopis signaling mutants and knock-out lines of candidate genes with the goal to correlate transcriptional changes with insect performance. Our aim is to identify genes that contribute to plant resistance to herbivores. We also study transcription factors that are specifically responsible for the activation these anti-herbivore genes.
Publications associated with this project: Plant Cell (2000) 12:707-719; Plant Cell (2004) 16:3132-3147; Molecular Plant-Microbe Interactions (2007) 20:1406-1420; Plant Journal (2008) 55:774-786; Plant Cell (2011) 23:701-715; Journal of Experimental Botany (2012) 63:727-737; Phytochemical Analysis (2012) 23:520-528; Frontiers in Plant Science (2013) 4:13.
2. Responses of Arabidopsis to insect eggs
Little is known on how plants respond to insect egg deposition at the molecular level. We study the response of Arabidopsis thaliana to egg deposition by the pierid butterfly Pieris brassicae. We found that egg deposition alters the expression of hundreds of genes in Arabidopsis and that one consequence is a suppression of plant defenses through manipulation of signaling pathways. We would like to identify egg-derived elicitors, their cognate plant receptors and molecular mechanisms by which eggs suppress jasmonate-dependent plant defenses against herbivory.
Publications associated with this project: Plant Physiology (2007) 143:784-800; Plant Signaling & Behavior (2007) 2:165-167; Plant Journal (2010) 62:876-885; Journal of Experimental Botany (2013) 64:665-674.
3. Whole-genome Arabidopsis transcript profiling
We monitor gene expression at the whole genome level with Arabidopsis DNA microarrays. As partners of the CATMA project (http://www.catma.org) we have designed and produced high quality Gene-specific Sequence Tags (GSTs) covering most Arabidopsis genes. The GST collection is used by numerous groups for the production of DNA arrays for transcript profiling experiments. We have printed a 25K microarray and use it for our research projects.
Publications associated with this project: Nucleic Acids Research (2003) 31:156-158; Genome Research (2004) 14:2176-2189; BMC Bioinformatics (2007) 8:400.
4. Kinship effects in Arabidopsis
Competition for resources lowers growth and fitness in most organisms. Studies in animals have revealed that relatedness between potential competitors is a key factor affecting the intensity of competitive interactions. As predicted by kin selection theory many animals can discriminate among related (kin) and unrelated (non-kin) individuals and they are less competitive toward kin. In plants, individuals of varying relatedness compete with one another, so kin selection is also likely to be important. This project aims to assess whether Arabidopsis plant growth patterns differ when two related (kin treatment) or two unrelated (non-kin treatment) plants are grown close together and what is the molecular basis for the observed changes. This project is done in collaboration with Laurent Keller (DEE, University of Lausanne) and was funded by the interdisciplinary research program of the FBM (http://www.unil.ch/fbm/page22586.html).
Publications associated with this project: New Phytologist (2010) 185:322-331, BMC Plant Biology (2012) 12:227.
5. Roles of volatiles in multitrophic interactions
Volatile organic compounds emitted by vegetation, also called biogenic volatile organic compounds (BVOC), are a diverse set of chemical molecules with a wide range of functions from plant ecology to chemical properties of the atmosphere and climate. From an ecological point of view, BVOC mediate vital organism functions and interactions. Using such emissions, plants attacked by herbivorous insects “call for help” attracting carnivorous insects to control herbivorous species. A limited number of signaling pathways are involved in controlling stress-induced plant BVOC emission. However, in nature plants are members of complex communities and exposed to multiple stresses that may have positive or negative consequences for the plant response.
We participate in an ESF-funded EUROCORE collaborative project called A-BIO-VOC (http://www.esf.org/index.php?id=6394). The overall goal is to study the effect of combinations of (a)biotic stresses on BVOC emission, gene expression level and community dynamics in a brassicaceous plant system. The specific aim of our project is to study the transcriptional responses of Brassica nigra and Arabidopsis plants subjected to combinations of stresses that trigger the jasmonic acid (JA) and salicylic acid (SA) pathways. Plants will be exposed to single attack by insect herbivores or will be challenged with insects in combination with oomycetes, aphids, insect eggs or ozone. The objective is to identify specific genes that are linked to a differential response of the plants to a single insect attack or to multiple attacks. The expression of these genes will be correlated with BVOC emission that will be measured by other partners of the consortium. In addition, the effect of combination of stresses on insect performance will underline the impact of pathway crosstalk on the effective defenses of the plant.