PhD position CNRS (M/F) – Environmental factors modulating Orobanche parasitism in oilseed rape

Job Description

Thesis Subject

Branched broomrape (Phelipanche ramosa) is an obligate parasite with a broad host range, causing major yield losses in oilseed rape. Its seeds can persist in the soil for more than ten years. Near its host plant, the seeds of this phytoparasite germinate and then attach to the oilseed rape roots through the formation of a haustorium, which connects the vascular systems of both plants. This underground interaction depends on complex, poorly understood mechanisms involving abiotic factors (temperature, soil water regime) and biotic factors (microbial communities). The interactions between the host and its microbiota/phytoparasite/environment result in high heterogeneity in P. ramosa infestation levels across agricultural fields, as well as significant difficulty in predicting parasitic risk at both intra- and inter-field scales. Furthermore, potential soil suppressiveness to broomrape has recently been demonstrated, suggesting the existence of microbial taxa that may be involved in controlling phytoparasite populations. However, the biological basis of this soil resistance and the microbial functions involved remain poorly understood. This PhD aims to identify the environmental factors (temperature, soil water regime, and microbial communities) that modulate the fitness of the phytoparasite P. ramosa in soils. The project is organized into three complementary axes. The first axis will analyze the impact of water regime, temperature, and their combination on parasite germination, attachment to its host, and the relationships between parasite fitness, oilseed rape growth, and microbiome structure. The second axis will seek to decipher the role of the microbiome by identifying taxa and functions associated with a reduction in oilseed rape phytoparasitism under controlled conditions. This will be based on a comparative analysis of microbiome structure depending on the soil's ability to promote or inhibit broomrape development. The third axis will focus on establishing (based on the results from the second axis) synthetic microbial communities (SynComs) capable of protecting oilseed rape, and then evaluating their ability under controlled conditions to limit phytoparasitism. This PhD project will contribute to a better understanding of the ecological determinants of oilseed rape parasitism by P. ramosa and will pave the way for biocontrol strategies based on microbiome and environmental condition manipulation.

Your Work Environment

This PhD project is funded by the ANR Orofit project (PRC ANR-25-CE32-3577). It will be co-supervised by C. Prigent-Combaret (Rhizosphere team, Microbial Ecology (LEM), CNRS UMR 5557, Lyon) and by S. Gibot-Leclerc (biodiverSE team, Agroecology, INRAe UMR 1347, Dijon). The PhD student will primarily conduct his/her research within the Rhizosphere team of CNRS UMR 5557 Microbial Ecology. Experiments on the impact of thermal stress on the plant parasite will be carried out within the Agroecology unit. Collaborations will be established with members of both units involved in the ANR OroFit project. In particular, the expertise of Y. Moënne-Loccoz, J. Almario, and D. Muller (Rhizosphere team) and that of the iBio platform of the Microbial Ecology UMR, as well as that of S. Mondy from the Agroecology UMR, will be sought for microbiome analysis and the identification of taxa potentially involved in parasite control. Other collaborative relationships will be established with members of the unit US2B of Nantes (You-lann Chevalier, Lucie Poulin, Phillippe Simier, and Jean-Bernard Pouvreau).

Constraints and risks

-

Compensation and benefits

Compensation

2300 € gross monthly

Annual leave and RTT

44 jours

Remote Working practice and compensation

Pratique et indemnisation du TT

Transport

Prise en charge à 75% du coût et forfait mobilité durable jusqu’à 300€

About the offer

About the CNRS

The CNRS is a major player in fundamental research on a global scale. The CNRS is the only French organization active in all scientific fields. Its unique position as a multi-specialist allows it to bring together different disciplines to address the most important challenges of the contemporary world, in connection with the actors of change.

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