Multi-drug-resistance (MDR) in septoria leaf blotch

Selim Omrane (1) , Colette Audeon (1) , Amandine Ignace (1) , Clémentine Duplaix (1) , Hind Sghyer (1) , Lamia Aouini (2) , Gert Kema (3) , Anne Sophie A. S. Walker (1) , Sabine Fillinger (1)

1 BIOGER - BIOlogie et GEstion des Risques en agriculture
2 Plant Research International
3 WUR - Wageningen University and Research [Wageningen]

Context: Multidrug resistance (MDR) is a common trait developed by many organisms to counteract chemicals and/or drugs. The basic MDR mechanism relies on an overexpressed efflux transport system that actively expulses the toxic agent. In fungi, MDR has been extensively studied in Saccharomyces cerevisiae, but also plant pathogenic fungi, e.g., Botrytis cinerea, are concerned by this phenomenon. In agriculture, it is currently under investigation if MDR strains may threaten the efficacy of fungicide treatments. MDR strains were detected in septoria leaf blotch (Zymoseptoria tritici) field populations since 2008 (Leroux & Walker, 2011). These strains are cross resistant to fungicides with different modes of action. Results: We have shown that this resistance is due to active fungicide efflux, potentially through the overexpression of one membrane transporter gene, MgMFS1 (Omrane et al., 2015). The inactivation of MgMFS1 abolished the MDR phenotype in at least one field strain. A bulk-segregant analysis (BSA) of two MDR isolates coupled to next generation sequencing showed a clear co-segregation between the MDR phenotype and the left arm of chromosome 7 covering MgMFS1 (Fig.1). We identified a 519 bp insert (LTR-like) in both MDR strains as well as in other MDR field strains. Genotyping of the progenies for the promoter insert showed a clear, but not exclusive correlation between the MgMFS1 promoter insert and the MDR phenotype. Current investigations are underway to analyze if the LTR-like insert - alone or in combination with a second mutation - confers the MDR phenotype through MgMFS1 overexpression. Conclusions: MDR is new resistance phenomenon in Z. trtici. It operates through fungicide efflux and involves overexpression of at least one major membrane transporter. Its evolution may be due to retrotransposon reminiscence, but additional mutations may be involved. The combination of mdr mutation(s) to target site mutations may threaten most fungicide treatments against septoria leaf blotch.

Mots clés: multi drug resistance; fungicide effux; retrotransposon; membrane transporter

Domaines: Sciences du Vivant [q-bio]

Selim Omrane, Colette Audeon, Amandine Ignace, Clémentine Duplaix, Hind Sghyer, et al.. Multi-drug-resistance (MDR) in septoria leaf blotch. 18. international Conference on Plant Protection, Aug 2015, Berlin, Germany. ⟨hal-01187021⟩