THESE: Rôle des protéines MILDEW RESISTANCE LOCUS O (MLO) végétales pendant l’infection par les oomycètes, une perspective évolutive.

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INRAE presentation

The French National Research Institute for Agriculture, Food, and Environment (INRAE) is a major player in research and innovation. It is a community of 12,000 people with 272 research, experimental research, and support units located in 18 regional centres throughout France. Internationally, INRAE is among the top research organisations in the agricultural and food sciences, plant and animal sciences, as well as in ecology and environmental science. It is the world’s leading research organisation specialising in agriculture, food and the environment. INRAE’s goal is to be a key player in the transitions necessary to address major global challenges. Faced with a growing world population, climate change, resource scarcity, and declining biodiversity, the Institute has a major role to play in building solutions and supporting the necessary acceleration of agricultural, food and environmental transitions.

Work environment, missions and activities

You will be hosted in the ISA unit (Institut Sophia Agrobiotech), a Joint Research Unit (UMR) INRAE-CNRS-Université Côte d'Azur. ISA gathers about 250 people working in particular on plant health and their interaction with pathogenic microorganisms (oomycetes, root-knot nematodes) and symbiotic microorganisms (nitrogen fixing bacteria), or with pests (insects). You will be integrated in the IPO (Plant-Oomycete Interactions) team. The PhD is funded for 3 years (starting October 1^st or November 1^st, 2025) by INRAE SPE Department and UniCA IdEX. 

Research Topic:

Plant cells have developed complex signaling pathways to coordinate their intracellular growth machinery with their extracellular cell wall, that shields them from the environment. These pathways, called cell wall integrity mechanisms, are governed by receptor-like kinases, including FERONIA (FER) and MARIS (MRI) proteins (1). Interestingly, we have shown that such mechanisms discovered in flowering plants are conserved in the early diverging land plant Marchantia polymorpha (2), an emerging simplified and powerful genetic plant model. Moreover, a recent multi-omic approach in the host team on knockdown mutants for Marchantia FER and MRI genes, indicates that the FER/MRI signalling module regulates abscisic acid and plant defence responses (3). Intriguingly, MRI was recently found to interact with MILDEW RESISTANCE LOCUS O (MLO) proteins to activate their calcium channel activity (4,5). The MLO loci were discovered more than 80 years ago in barley as the first plant susceptibility S factors and have been since used successfully in agriculture to provide broad and robust resistance in different crops to the filamentous powdery mildew fungi (6). The role of the 7 transmembrane domains containing MLO proteins unique to plants (7) during interaction with filamentous oomycetes remains however largely unexplored despite similar infection strategies.

Research Goal:   

This PhD project aims first at characterizing the response of mlo mutants in both the tracheophyte Arabidopsis and the bryophyte Marchantia model plants to infection by parasitic oomycetes of the Phytophthora genus. Preliminary experiments with T-DNA insertional and CRISPR/Cas9 knock-out mutants for some of the 15 Arabidopsis AtMLO genes and the 4 MpMLO genes in Marchantia indicate that indeed MLOs modulate the outcome of plant-Phytophthora interaction.

Secondly, Marchantia MLO coding sequences will be cloned and used for (i) subcellular localization before and during oomycete infection as MLOs are known to be recruited to the fungi penetration site (8), (ii) interaction assays with both MpMRI and AtMRI (5), (iii) as well as calcium channel activities and (iv) (transspecies) mutant complementation. Finally, protein sequences and structures analyses will guide us to engineer targeted mutations in key residues responsible for regulating plant-Phytophthora outcome. This project should reveal how MLO function has evolved during land plant evolution and whether early-diverging plant MLO proteins could constitute untapped resources for engineering disease resistance to devastating oomycete by loss of susceptibility (9).

The candidate will benefit from newly established semi-automated pipelines to quantify symptoms on Arabidopsis and Marchantia plants, state-of-the-art tools for the genetic manipulation of plant and Phytophthora model species, as well as biochemistry expertise from the Plant-Oomycete Interaction team at the Sophia Agrobiotech Institute (Accueil - IPO (inrae.fr).

 

Project references:

¹Franck CM, Westermann J, and Boisson-Dernier A (2018). Plant Malectin-Like Receptor Kinases: From Cell Wall Integrity to Immunity and Beyond. Annu. Rev. Plant Biol. 69:301-28. https://doi.org/10.1146/annurev-arplant-042817-040557

²Westermann J, Streubel S, Franck CM, Lentz R, Dolan L, and Boisson-Dernier A (2019). An Evolutionarily Conserved Receptor-like Kinases Signaling Module Controls Cell Wall Integrity During Tip-Growth. Curr Biol. 22:3899-3908.e3 https://doi.org/10.1016/j.cub.2019.09.069

³Jobe T, Gaspar Litholdo Jnr C, Stolze SC, Stephan L, Westermann J, Harzen A, Hülskamp M, Nakagami H, Boisson-Dernier A. (2024). An Omics approach on Marchantia polymorpha single FERONIA and MARIS homologs confirms links between cell wall integrity and abscisic acid. bioRxiv https://doi.org/10.1101/2024.11.26.625412

⁴Gao Q, Wang C, Xi Y. et al. (2022). A receptor–channel trio conducts Ca²⁺ signaling for pollen tube reception. Nature 607, 534–539. https://doi.org/10.1038/s41586-022-04923-7

⁵Gao Q, Wang C, Xi Y. et al. (2023). RALF signaling pathway activates MLO calcium channels to maintain pollen tube integrity. Cell Res 33, 71–79 https://doi.org/10.1038/s41422-022-00754-3

⁶Jacott CN, Ridout CJ, Murray JD (2021). Unmasking Mildew Resistance Locus O. Trends Plant Sci. 26:1006-1013. https://doi.org/10.1016/j.tplants.2021.05.009

⁷Kusch S, Pech L, Panstruga R. (2016). Comprehensive Phylogenetic Analysis Sheds Light on the Diversity and Origin of the MLO Family of Integral Membrane Proteins. Genome Biol Evo https://doi.org/10.1093/gbe/evw036

⁸Qin L, Zhou Z, Li Q et al. (2020). Specific Recruitment of Phosphoinositide Species to the Plant-Pathogen Interfacial Membrane Underlies Arabidopsis Susceptibility to Fungal Infection. Plant Cell 32, 1665–1688. https://doi.org/10.1105/tpc.19.00970

⁹Koseoglou E, van der Wolf JM, Visser RGF, Bai Y (2022) Susceptibility reversed: modified plant susceptibility genes for resistance to bacteria. Trends Plant Sci. 27:69-79. https://doi.org/10.1016/j.tplants.2021.07.018 

Training and skills

Desired knowledge: Strong interest in plant biology, general knowledge of developmental, cellular and molecular biology.

Appreciated experience: Phenotyping of living organisms at cellular level, molecular biology and biochemistry (PCR, cloning), culture in vitro, confocal microscopy and image analysis. Knowledge of molecular plant-microbe interactions is a plus.

Desired skills: Motivated candidate, strongly involved in his/her research project and capable of solving scientific problems, critically discussing experimental results and interacting with scientists from different backgrounds. The working languages of the laboratory and institute are French and English. Excellent writing and communication skills are required.

INRAE's life quality

By joining our teams, you benefit from (depending on the type of contract and its duration):

- up to 30 days of annual leave + 15 days "Reduction of Working Time" (for a full time);
- parenting support: CESU childcare, leisure services;
- skills development systems: training, career advise;
- social support: advice and listening, social assistance and loans;
- holiday and leisure services: holiday vouchers, accommodation at preferential rates;
- sports and cultural activities;
- collective catering.

How to apply

I send my CV and my motivation letter