Non-target site resistance does matter!

A study aiming at exploring the putative resistance mechanisms that might be selected in the future in field pathogen populations undergoing exposure to metyltetraprole, allowed the identification, among others, of a bypass resistance mechanism involving the activation of the alternative oxidase AOX and complex III inhibitors (Mosser et al, 2023). By examining the genetic diversity associated with MDR in Z tritici populations during his PhD, Simon Patry-Leclaire has revealed an unsuspected diversity of P_MFS1 genotypes (responsible for a potential overexpression of the membrane efflux pump MFS1), partly resulting from intense transposable elements dynamics. He also concluded that mechanisms underlying MDR may be more complex than previously thought and may involve other mechanisms that have yet to be described (Patry-Leclaire et al, 2023).

These new MDR mechanisms are under investigation by Elza Neau in her PhD: some rely on increased efflux due to transporters other than MFS1, whereas others rely on as yet unknown mechanisms distinct from increased efflux still. More generally, studying mechanisms of NTSR and their contribution to the phenotype of resistance is original and a signature of the AMAR team, as most groups conducting research on the resistance to agricultural fungicides massively concentrate on fungicide target site alteration.

REFERENCE :  S. Patry-Leclaire, A. Pitarch, A-S. Walker, S. Fillinger. Plasticity of the MFS1 promotor is not the only driver of Multidrug resistance in Zymoseptoria tritici. 2023. BioRxiv, ⟨10.1101/2023.12.27.573052⟩.