CNRS-ISV,1 avenue de la Terrasse,Bat 23, 91198 Gif sur Yvette,FranceMini-biographyMy Laboratory is mainly interested in the molecular mechanisms involved in the regulation of root architecture and development in the models
Arabidopsis thaliana and
Medicago truncatula. We have been developing genomic approaches to analyze the role of specific regulatory genes and abiotic stresses on root growth and differentiation. We are particularly interested in the role of non-coding RNAs in these processes and we have characterized a riboregulator of the symbiotic interaction in Medicago roots. We have also recently developed transgenic plants expressing GFP in specific tissues that allowed us to visualise changes in root architecture and cell-to-cell communication induced by the interaction of legume roots with the soil environment. Using genomic approaches, our group has characterized more than a hundred candidate regulatory genes linked to changes in root growth and differentiation in response to environmental constraints. I am also involved in GLIP, the Grain Legumes Integrated Project of the FP6-EEC Program as coordinator of the WP4.1 dealing with abiotic stress responses. Our group is now actively investigating the role of micro RNAs in the regulation of root developmental plasticity. The group is housed in the Institut de Sciences du Végétal at Gif sur Yvette, in the Paris suburban area.
Identifying key regulators involved in abiotic stress adaptation of legumes using the model M. truncatulaM. Crespi, T. Huguet, V. Gruber, C. Ameline-Terragrossa, F. Frugier, A. Diet, L. De Lorenzo, S. Blanchet, F. Merchan
Institut des Sciences du Végétal-CNRS, Gif sur Yvette, France
Martin.Crespi@isv.cnrs-gif.frThe rapid development of genomic tools in the model legume
M. truncatula opens a wide variety of possibilities to explore diverse physiological processes which have a significant impact in crop legume productivity. Abiotic stresses impose major constraints in legume crops and we are combining transcriptomic and QTL approaches in
M. truncatula to identify key regulators allowing adaptation to soil abiotic stresses, notably root growth. Using expression analysis of 16000 genes (Mt16kOLI1Plus microarray) as well as other genomic approaches (substractive hybridization) we have identified a collection of regulatory genes in root apexes, the region of the root where meristem lies and determines root growth, affected by salt stress. Statistical analyses revealed significant changes in 826 genes after a one-hour stress with 100 mM salt. Among them, 95 sequences (11.5%) corresponded to transcription factors (TF). In parallel, we have used a platform for massive analysis of TF expression using quantitative RT-PCR in
M. truncatula. Out of a collection of 39 TFs characterised in more detail, 12 TFs were selected due to their robust induction in different stress conditions for further functional analysis. In total, we have identified 107 TF genes, including members of HD-ZIP, NAC/NAM, WRKY, Dof Zn-finger, MYB, EREBP and PR/ERF families, as well as several new elements (Receptor kinases, hormone receptors) of the regulatory networks activated by salt stress in the root apex.
In parallel, QTLs linked to changes of a variety of physiological parameters induced by salt stress have been characterised in
M. truncatula. Genomic novel information derived from the sequencing of
M. truncatula is being used to speed up the analysis of a variety of
M. truncatula genes, including the large TF collection previously mentioned, to define candidate genes co-localising with these QTLs. Refined expression analysis of specific candidate regulatory genes was performed in
M. truncatula cultivars that differed in their responses to salt stress. For example, a Krüppel transcription factor (TF), a new RNA-binding protein and a new Receptor-like kinase were shown to be involved in the regulation of root growth adaptation to salt stress using functional approaches like RNAi or TILLING. This combination of genomics, functional and physiological analysis (e.g. reverse genetics) in the model legume will provide new molecular markers for breeding programs and, most importantly, can significantly accelerate the functional characterisation of key genes and networks involved in the control of legume adaptation to abiotic stresses.
