Background and challenges

Faced with this situation, how can we ensure sustainable crop protection? This seemingly simple question has been the subject of decades of debate and intense research effort.

Based on a bibliometric analysis, we have shown that research into the sustainability of plant resistance is highly structured, with a clear split between molecular approaches and epidemiological studies. This cleavage certainly hinders scientific progress. As a solution, we believe that the tools and concepts of population genetics should be used, as this discipline enables us to integrate the study of genetic bases at the higher scales of host and pathogen populations.

Objectives 

We therefore propose an intrinsically multidisciplinary project combining molecular plant pathology experiments and demo-genetic modeling. To this aim, we focus on L. maculans, a fungal pathogen causing blackleg disease on various Brassica crops including oilseed rape. For this pathosystem, there is both a good knowledge of the molecular basis of interactions and a temporal monitoring of pathogen populations. We will also take into account the unconventional interactions that have been described for this pathosystem.

The main aim of this PhD thesis is to trace the demographic and adaptation dynamics of L. maculans populations during overcoming of genetic resistances, to infer their evolutionary potential. The project is divided into three complementary axes aiming to:

1. Characterize the temporal evolution of L. maculans populations, both at avirulence loci (subject to selection) and at neutral loci witnessing the demographic regime
2. Determine by modeling the expected dynamics of overcoming when there are epistatic interactions between loci
3. Characterize the expected genetic signatures (at neutral and selected loci) after multiple overcoming events and infer the parameters of this demo-genetic model from the observed data.

Our ambition is, on the one hand, to train a person at the interface between molecular characterization and evolutionary trajectory analysis, to strengthen the dialogue between these two scientific communities interested in the sustainability of plant resistance; and, on the other hand, to propose innovative and relevant resistance management scenarios based on system biology and the consideration of epidemio-evolutionary feedbacks.

Involved research units for supervision:

Contacts / coordination :