Symbiotic signal perception and arbuscular mycorrhiza in non-legumes.
The arbuscular mycorrhizal (AM) symbiosis. Most plants including cereals form an endosymbiosis with AM fungi belonging to the group of Glomeromycota. AM fungi are beneficial for plants because of their ability to colonize both soil and roots and collect nutrients from a much higher soil volume than plant roots. AM fungi penetrate root cortical cells and exchange nutrients through structures called arbuscules. AM fungi provide soil nutrients (phosphorus, nitrogen and other nutrients) to plants and benefit from fixed carbon (photosynthates) from the plants through carbohydrate and lipid tranfers. AM fungi can also protect plants from biotic and abiotic stress. This interaction is described as a mutualistic symbiosis, however antagonistic effects on plant host growth can sometimes be observed.
A tomato root colonized by a strain of the AM fungus Rhizophagus irregularis. The fungus is stained by ink (blue). Arrows show arbuscules. Arrowheads show extraradical hyphae.
Our research: We are interested in understanding plant molecular mechanisms which influence 1/ host colonization by AM fungi and 2/ mycorrhizal growth response (which can positive or negative).
Plant models: In 2012, I initiated studies on model and crop plants including dicots: Nicotiana benthamiana and Solanum lycopersicum (tomato) and monocots: Brachypodium distachyon and Triticum aestivum (wheat).
A B. distachyon plant grown for 9 weeks in a growth chamber.
Note that Arabidopsis thaliana, a widely used plant model is one of the few plants unable to form the AM symbiosis.
Objective 1: To determine the role of signal molecules produced by AM fungi in the establishment of the symbiosis. Lipo-chitooligosaccharidic (LCO) and short chitooligosaccharidic (CO) produced by AM fungi are able to activate a host signalling pathway required for host colonization by AM fungi and thus LCOs and COs are likely involved in mechanisms of host colonization. Our strategy consists of the identification and characterization of plant LCO and CO receptors. Candidates belong to the family of Receptor-Like Kinases (RLKs) containing LysM domains. We are characterizing LCO or CO binding properties of LysM-RLKs using radiolabelled molecules or Microscale Thermophoresis. We are also determining the biological roles of these receptors by reverse genetic approaches. We also aim to purify LCO or CO binding proteins from membrane fractions and to identify them by mass spectrometry.
Objective 2: To identity the genetic determinants and the molecular mechanisms that control plant benefit from AM fungi. To address this objective, we are investigating the natural genetic variability of B. distachyon. This includes analysis of growth and transcriptional responses of plants to various AM fungal strains in various environments. The aim is to identify molecular mechanisms that are critical for mycorrhizal growth responses using quantitative genetic approaches. For this, we use the new Toulouse plant phenotyping platform to measure growth kinetics of various B. distachyon genotypes in the presence or the absence of AM fungi.
We have also initiated a research program to explore the interactions between bacterial and AM fungal communities associated with wheat roots in fields, and their effects on plant benefit from AM fungi. To do this, we characterize the communities by metagenomic approaches and isolate the bacterial strains. The growth of various wheat cultivars will be measured in the presence or the abscence of combinations of isolated bacteria and AM fungi.
- Benoit Lefebvre, researcher
- Luis Buendia, PhD student (Ministerial fellowship, co-supervision with S. Bensmihen).
- Ariane Girardin, PhD student (INRA-Région Midi-Pyrénées fellowship)
- Tongming Wang, PhD student (Chinese Scholarship Council fellowship)
- Claudia Bartoli, post-doc (RHIZOWHEAT grant)
- Mégane Gaston, assistant IE (WHEATSYM grant)
- Virginie Gasciolli, Technician
- Marie Cumener (assistant IE, 2012-2014)
- Project WHEATSYM (ANR), 2017-2021, coordinator: B. Lefebvre
- Projet Stress'n'Sym (Institut Carnot Plant2Pro), 2017-2020, coordinateur: B. Lefebvre
- Projet RHIZOWHEAT (IDEX ATS), 2016-2017, coordinateur: C. Masson (LIPM)
Recent Publications (2012-2016)
Lefebvre B. 2017. Arbuscular mycorrhiza: A new role for N-acetylglucosamine. Nature Plants 3, 17085
Vernié T., Camut S., Camps C., Rembliere C., de Carvalho-Niebel F., Mbengue M., Timmers T., Gasciolli V., Thompson R., Le Signor C., Lefebvre B., Cullimore J. and Hervé C. 2016. PUB1 interacts with the receptor kinase DMI2 and negatively regulates rhizobial and arbuscular mycorrhizal symbioses through its ubiquitination activity in Medicago truncatula. Plant Physiol 170: 2312-2324
Buendia L., Wang T., Girardin A. and Lefebvre B. 2016. The LysM receptor-like kinase SlLYK10 regulates the arbuscular mycorrhizal symbiosis in tomato. New Phytol 210, 184-195
Fliegmann J., Canova S., Lachaud C., Uhlenbroich S., Gasciolli V., Pichereaux C., Rossignol M., Rosenberg C., Cumener M., Pitorre D., Lefebvre B., Gough C., Samain E., Fort S., Driguez H., Vauzeilles B., Beau J.M., Nurisso A., Imberty A., Cullimore J. and Bono J.J. 2013. Lipo-chitooligosaccharidic symbiotic signals are recognized by the LysM receptor like kinase LYR3 in the legume Medicago truncatula. ACS Chemical Biology 8: 1900-1906
Pietraszewska-Bogiel A., Lefebvre B., Koini M.A., Klaus-Heisen D., Takken F.L.W., Geurts R., Cullimore J.V and Gadella T.W.J. 2013. Interaction of Medicago truncatula Lysin motif receptor-like kinases, NFP and LYK3, produced in Nicotiana benthamianaleaf induces a defence-like response. PlosOne 8(6):e65055
Park C.J., Sharma R., Lefebvre B., Canlas P.E, and Ronald P.C. 2013. Endoplasmic reticulum-quality control component SDF2 is essential for XA21-mediated immunity in rice. Plant Science 210:53-60