Fenhexamid - an efficient and inexpensive fungicide for selection of Magnaporthe oryzae transformants

Alex Wegner,Louisa Wirtz,Thomas Leisen,Matthias Hahn,Ulrich Schaffrath

doi:10.1007/s10658-021-02432-3

Abstract

Magnaporthe oryzae is one of the most economically important phytopathogenic fungi, and is used as a model organism to study plant-pathogen interactions. To unravel the infection process, forward and reverse genetic approaches are essential, but are often hindered by the lack of a straightforward selection procedure for transformants. Here we report on the use of fenhexamid, an inhibitor of ergosterol biosynthesis, for selection of M. oryzae transformants. An allele of the sterol 3-ketoreductase gene of Fusarium fujikuroi (FfERG27), known to confer resistance to fenhexamid, has already been used successfully with transformants of Botrytis cinerea. Our results demonstrate that expression of the FfERG27 allele in M. oryzae also enables highly efficient selection of transformants on fenhexamid-containing media. The use of fenhexamid is an inexpensive alternative for selection as compared to commonly used antibiotics like hygromycin. No impact on growth and infection phenotypes of fenhexamid resistant M. oryzae mutants was detected, which underpins its usefulness for selecting M. oryzae transformants.

Highlights

The ascomycete M. oryzae, best known as the causal agent of rice blast disease, has become a major thread for rice and for wheat cultivation (Martinez et al, 2021; Portz et al, 2021)
We report on the use of fenhexamid resistance conferred by the gene FfERG27 of Fusarium fujikuroi to select transgenic M. oryzae mutants as described previously for Botrytis cinerea (Cohrs et al, 2017)
Fenhexamid in combination with the resistanceconferring gene FfERG27 of F. fujikuroi is wellestablished for selection of B. cinerea transformants (Cohrs et al, 2017)

Summary

Introduction

The ascomycete M. oryzae, best known as the causal agent of rice blast disease, has become a major thread for rice and for wheat cultivation (Martinez et al, 2021; Portz et al, 2021). We report on the use of fenhexamid resistance conferred by the gene FfERG27 of Fusarium fujikuroi to select transgenic M. oryzae mutants as described previously for Botrytis cinerea (Cohrs et al, 2017). For F. fujikuroi a field isolates (IMI 58289) was identified with an allele of the ERG27 gene (FfERG27) that mediates resistance against fenhexamid and which was used for selection of B. cinerea transformants (Cohrs et al, 2017). Using this knowledge, we broaden the tool box for M. oryzae by establishing fenhexamid as an effective and cost-efficient selection marker in transformation

Experimental procedures

Results

Discussion