Transposition of the miniature inverted-repeat transposable element mimp1 in the wheat pathogen Fusarium culmorum

Summary High‐throughput methods are needed for functional genomics analysis in Fusarium culmorum, the cause of crown and foot rot on wheat and a type B trichothecene producer. Our aim was to develop and test the efficacy of a double‐component system based on the ability of the impala transposase to transactivate the miniature inverted‐repeat transposable element mimp1 of Fusarium oxysporum. We report, for the first time, the application of a tagging system based on a heterologous transposon and of splinkerette‐polymerase chain reaction to identify mimp1 flanking regions in the filamentous fungus F. culmorum. Similar to previous observations in Fusarium graminearum, mimp1 transposes in F. culmorum by a cut‐and‐paste mechanism into TA dinucleotides, which are duplicated on insertion. mimp1 was reinserted in open reading frames in 16.4% (i.e. 10 of 61) of the strains analysed, probably spanning throughout the entire genome of F. culmorum. The effectiveness of the mimp1/impala double‐component system for gene tagging in F. culmorum was confirmed phenotypically for a putative aurofusarin gene. This system also allowed the identification of two genes putatively involved in oxidative stress‐coping capabilities in F. culmorum, as well as a sequence specific to this fungus, thus suggesting the valuable exploratory role of this tool.