Summary Fusarium oxysporum f. sp. melonis (Fom) is one of the most important pathogens of melon worldwide. In this study, we investigated the genomic diversity of Fom. One of the aims was to find clues for the origin(s) and dispersal of clonal lineages and races of Fom. We therefore included a large number of Fom strains from Iran, where melon has been cultivated for at least 5000 years. In 33 new genome sequences of Fom strai...

Summary In Fusarium oxysporum f.sp. lycopersici , all effector genes reported so far – also called SIX genes – are located on a single accessory chromosome which is required for pathogenicity and can also be horizontally transferred to another strain. To narrow down the minimal region required for virulence, we selected partial pathogenicity chromosome deletion strains by fluorescence‐assisted cell sorting of a strain in which...

Endophytic microbes conferring biocontrol are an eco-friendly alternative to control diseases in crops. Unfortunately, the use of endophytes to control diseases is not yet widespread as their application in agricultural settings is challenging and the outcome variable. Translating strains that perform well under laboratory conditions to the field poses several challenges. One is large scale inoculum production in a cost-effect...

Summary Horizontal transfer of supernumerary or lineage‐specific (LS) chromosomes has been described in a number of plant pathogenic filamentous fungi. So far it was not known whether transfer is restricted to chromosomes of certain size or properties, or whether ‘core’ chromosomes can also undergo horizontal transfer. We combined a directed and a non‐biased approach to determine whether such restrictions exist. Selection gene...

Summary Formae speciales (ff.spp.) of the fungus Fusarium oxysporum are often polyphyletic within the species complex, making it impossible to identify them on the basis of conserved genes. However, sequences that determine host‐specific pathogenicity may be expected to be similar between strains within the same forma specialis . Whole genome sequencing was performed on strains from five different ff.spp. ( cucumerinum , niveu...

Summary Genome sequencing of F usarium oxysporum revealed that pathogenic forms of this fungus harbour supernumerary chromosomes with a wide variety of genes, many of which likely encode traits required for pathogenicity or niche specialization. Specific transcription factor gene families are expanded on these chromosomes including the EBR1 family ( E nhanced B ranching). The significance of the EBR1 family expansion on supern...

Summary Fusarium oxysporum is an asexual fungus that inhabits soils throughout the world. As a species, F. oxysporum can infect a very broad range of plants and cause wilt or root rot disease. Single isolates of F. oxysporum, however, usually infect one or a few plant species only. They have therefore been grouped into formae speciales (f.sp.) based on host specificity. Isolates able to cause tomato wilt (f.sp. lycopersici ) d...