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24, chemin de Borde Rouge –Auzeville – CS52627
31326 Castanet Tolosan CEDEX - France

Dernière mise à jour : Mai 2018


Laboratory of Plant-Microbe Interactions - LIPM

Laboratory of Plant-Microbe Interactions

Research themes - Endosymbiotic infection and nodule development

(I) Regulation and dynamics of rhizobial infection


Endosymbiotic root entry takes place in most Fabaceae legume species, via de novo constructed tubular structures, called infection threads that guide rhizobia transcellularly towards the nodule primordia. By using molecular genetics, we have identified key ERF transcription regulators that orchestrate infection thread development and progression in Medicago (Andriankaja et al., 2007; Cerri et al., 2012, 2016, 2017; Liu et al., 2019). We now combine comparative transcriptomics, as well as other molecular and genetic approaches to decipher the genetic pathways they regulate. Our team also largely uses live cell imaging approaches to understand the dynamics of infection thread development and associated cellular signaling. In this context, we have developed a series of fluorescence markers (e.g. calcium sensors and symbiotic protein fusions) and discovered specific cellular remodeling responses and a new symbiotic protein complex contributing to infection thread growth in Medicago (Fournier et al., 2015; Kelner et al., 2018; Liu et al., 2019b). We are now combining various strategies (including cell-type specific molecular and cellular approaches) to understand plant-bacterial cross talk and plant cell reprogramming for bacterial infection. Finally, our work has also shown that the host plant promotes the creation of symplastic cellular communications to coordinate nodule development and bacterial colonization (Gaudioso-Pedraza et al., 2018), a process that we are currently studying in a broader context of other root symbioses.


Joëlle Fournier (CR CNRS) & Fernanda de Carvalho-Niebel (DR CNRS)


International: A. Becker (SYNMIKRO, Marburg); E. Larrainzar (University of Navarra, Spain); M. Marín & M. Parniske (LMU, Munich); J. Murray (JIC, UK; Institute of Plant Physiology & Ecology, CAS, Shanghai, China); Y. Benitez-Alfonso (University of Leeds, UK). National: F. Cartieaux & Sergio Svistoonoff (LSTM, Montpellier); P. Frendo & E. Boncompagni (ISA, Sophia-Antipolis); Local: R. Peyraud (iMEAN, Toulouse); N. Frei-Dit-Frey, P-M. Delaux & E. Jamet (LRSV, Toulouse); D. Capela (LIPM, Toulouse).


ANR-DFG PRCI Live Switch (2020-2024), INRAE-SPE CREPE (2020-2023); FRAIB-AO-CROSS (2019-2021); ANR-DFG PRCI COME-IN (2015-2019). 

(II) Master regulators of nodule development


Nodule development in Medicago involves the mitotic activation of root cells following a precise cell division pattern. This gives rise to a nodule structure composed of an apical meristem, enabling nodule growth throughout its lifetime, followed by successive zones of coordinated bacterial and plant cell differentiation, for creating the appropriate microenvironment for symbiotic nitrogen fixation. We study in the team main regulators of these crucial developmental transitions: (i) meristem formation and (ii) nodule differentiation.  

NF-YA1, a CCAAT-box-binding heterotrimeric transcription factor, has been characterized in the team as a main regulator of nodule development in Medicago (Combier et al., 2006; Laloum et al., 2013; Laloum et al.,, 2014; Laporte et al., 2014; Baudin et al., 2015). Besides contributing to early signalling and infection, a nodule fate-map analysis revealed the crucial importance of NF-YA1 for the regulation of nodule meristem formation (Xiao et al., 2014). In order to understand the mode of action of NF-YA1 we are currently identifying and characterising NF-YA1 target genes (Shrestha et al., 2020) as well as protein and epigenetic components of NF-YA1-associated regulatory mechanisms.

By the development of laser capture microdissection (LCM)-RNAseq approaches, the team  generated valuable resources for the scientific community (Jardinaud et al., 2016; Roux et al., 2018), as the first nodule zone-specific plant and rhizobium transcriptome (Roux et al., 2014; This and previous studies enabled to identify key plant regulators of nodule differentiation, including EFD, a crucial ERF transcription factor regulating cytokinin responses via RR4 (Vernié et al., 2008) and new epigenetic mechanisms. Indeed, the team demonstrated a precise spatial-regulation of DNA methylation-associated genes in nodules, the key role of the DNA demethylase DEMETER for nodule differentiation and the preferential clustering of nodule differentiation genes in genomic regions called symbiotic islands, enriched in epigenetic marks (Satgé et al., 2016; Pecrix et al., 2018). The group is currently pursuing the analysis of these important transcription and epigenetic regulators of nodule differentiation.  


Pascal Gamas (DR CNRS) & Andreas Niebel (DR CNRS)


International: F. Ariel (University of Santa Fe, Argentina); F. Blanco & E. Zanetti (University of La Plata, Argentina); E. Larrainzar (University of Navarra, Spain); J. Murray (JIC, UK; Institute of Plant Physiology & Ecology, CAS, Shanghai, China); K. Szczyglowski (University of Western Ontario, Canada); S. Sinharoy (National Institute of Plant Genome Research, New Delhi India). National: M. Benhamed, M. Crespi, F. Frugier (IPS2, Paris-Saclay); P. Frendo (ISA, Sophia-Antipolis). Local: J. Gouzy (LIPM).


ANR PioSYM (2019-2024), CNRS-LIA (International associated laboratory) France-Argentina NOCOSYM (2018-2021); ANR EPISYM (2016-2020).