Research teams

Nitrogen Use, Transport and Signaling

NUTS 14 members

Project 1: Nutrient-driven conserved TOR (Target of Rapamycin) protein kinase signaling pathway
(contact Christian Meyer and Anne-Sophie Leprince)
The conserved TOR (Target of Rapamycin) protein kinase acts in TORC1 (TOR complex 1) with LST8 and RAPTOR protein partners. This complex is found in all eukaryotes. In animals it is implicated in various proliferative and metabolic diseases including diabetes and cancer. TOR is a central player of the plant responses to the availability of nutrients but also to abiotic and biotic stresses and hormones.
TOR is a switch turning on anabolic and growth processes when conditions are favourable while inhibiting catabolism and nutrient recycling by autophagy. TOR controls mRNA translation globally but also the translation of specific mRNAs such as those encoding proteins needed for stress or hormone responses. Recent evidence suggests that TOR and SnRK1/2 (Snf1-related kinases) act in an opposing way.
Our ongoing projects:
• Characterize and identify components of the TOR signaling pathway by genetic approaches (suppressor screens resistance to inhibitors) – ANR project DECORATOR 2015-2019
• Investigate the role of TOR in plant stress responses and stress-related metabolites accumulation (proline, raffinose)

Project 2: Specific features of nitrate transport in Brachypodium
(contact Sylvie Ferrario-Méry)
Nitrate is both the major source of nitrogen, at least under our temperate culture conditions, and the first stored nitrogen compound which can be used and transported within the plant to sustain growth under external constraints. We study the molecular mechanisms that govern soil nitrate uptake by plant roots and its transport, storage and mobilization within the whole plant during development. We particularly focus our studies on the high affinity nitrate transport system, which involves the NRT2 protein family. After the in-depth study of the main NRT2 proteins in Arabidopsis, we are currently studying of nitrate transport in Brachypodium in relation to NUE. Our aim is to decipher the role and function of some BdNRT2 family members with a main focus on BdNRT2A as a good candidate for being the main nitrate transporter under low nitrate supply.


Project 3: Nitrate signaling in Arabidopsis, Brachypodium and barley with emphasis on the role of NLP transcription factors
(contact: Anne Krapp, Thomas Girin and Christian Meyer)
The plant responses to nitrogen availability requires mechanisms of sensing and regulation that control and coordinate the transport and the assimilation of nitrogen at both cellular and whole plant level. The NLP gene family is homologous to a gene essential for nodulation in legumes (NIN) and to the CrNit2 in Chlamydomonas that regulates nitrate assimilation. NLPs are members of the so-called RWP-RK protein family and are coding for transcription factors. We have shown that AtNLP7 is one of the master regulators of primary nitrate response (PNR) in Arabidopsis. Interestingly, the regulation by nitrate involves a nuclear/cytoplasm shuttling of the protein.
Our ongoing projects:
• Elucidation of the cell type-specific roles of AtNLP7 in roots - ANR project IMANA (2014-2019)
• Deciphering the molecular mechanisms that underlie the rapid activation of AtNLP7 by nitrate - ANR project NitraSense (2017-2021)
• Deciphering the PNR mechanism in C3 cereals – ANRprojet  NiCe (2017 -2021)
• Disentangling the mechanisms involved in nitrate-regulated germination – ANR project MAPKseed (2018-2022)


Project 4: The coordinated responses between N constraint and other stresses (combined stresses in particular with water stress)
(contact: Christian Meyer and Anne Krapp)
Due to climate changes, crop production will suffer from combinations of nutrient, water and/or temperature stresses. In collaboration with the IJPB-VAST team we aim to decipher the regulatory pathways underlying the interplay of adaptive responses to N availability and additional stress responses using functional genomics, quantitative genetics and omic approaches taking advantage of the IJPB phenotyping platform (Phenoscope node of the Plant Observatory).


Project 5: Role of N signaling and use in the beneficial interaction between microorganisms and plants
(contact: Thomas Girin, Sylvie Ferrario-Méry and Anne Krapp)
 Interactions with some microbes are known to enhance plant growth and development, for instance through positive effects on nutrient uptake or on pathogen resistance. Their use in agriculture (biostimulation and biocontrol) is however limited nowadays, as these microorganisms can also be detrimental to the plant depending on the environment and on the partner genotypes. No single biological function has been identified to explain the beneficial symbiosis effect on the plant nor the variability of benefit between plant genotypes, suggesting interactions between several effects. Our ongoing projects:
- Study of the modification and impact of N transport, use and signaling during the plant interaction with the symbiotic root-colonizing endophytic fungus Serendipita indica – CNRS EIG-Concert Japan project
- Identification of genetic and physiological basis triggering the diversity of response of Brachypodium in  symbiosis with the arbuscular mycorrhizal fungi (AMF) Rhizophagus irregularis – Carnot Plant2Pro project Stress’n’Sym (collaboration with Benoît Lefebvre (LIPM, Toulouse) and Marie Dufresne (IPS2, Orsay))
- Elucidation of the link between biocontrol and biostimulation from a strain of Trichoderma fungus on wheat – Carnot Plant2Pro project TrichoKissCool (collaboration with Marie Dufresne (IPS2, Orsay))
Nitrogen Use, Transport and Signaling

Leader:

Anne Krapp
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