Post-doc position BIOGER

This postdoctoral project is part of the ANR COMBINE project. One objective is to evaluate multi-scale varietal diversification scenarios that enable effective and sustainable control of septoria leaf blotch caused by the fungus Zymoseptoria tritici. Previous results show that varietal mixtures enhance the durability of resistance through various demographic and genetic processes (Orellana-Torrejon et al., 2022).

The Landsepi model, initially applied to cereal rusts (Rimbaud et al., 2018a & 2018b), was adapted for grapevine downy mildew, caused by the oomycete Plasmopara viticola, by integrating a module that simulates the sexual phase of the pathogen’s life cycle (Zaffaroni et al., 2024a,b). A first parameterization of the model for Z. tritici, which also alternates between asexual and sexual reproduction phases, was carried out during a Master’s internship (Sesia, 2024). You will first continue this parameterization using here key life-history traits of the pathogen and data available in the team then you will use Landsepi to simulate the effects of: (i) landscapes sensu lato composed of different resistant wheat varieties, and (ii) the introduction of varietal mixtures, themselves composed of resistant varieties, within these landscapes, on the evolution of epidemic intensity and the frequency of virulent strains in fungal populations.

You will test the hypothesis that the genetic diversity of wheat populations (number, frequencies, effects, and combinations of resistance genes) effectively contributes to disease reduction over multiple years. You will develop and evaluate scenarios in two contexts studied experimentally by the team: (i) in the French context, considering mixtures of wheat varieties possessing different resistance genes, based on ongoing micro-plot trials (Suffert et al., 2024); in the Tunisian context, considering wheat landrace populations that experience low disease incidence despite high pathogen pressure, based on an ongoing study aimed at characterizing the genetic architecture of resistance.

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