QTL mapping for aggressiveness variation in F. graminearum revealed one causal mutation in FgVe1 velvet protein

Résumé 0

Fusarium graminearum is one of the most frequent causal agent of the Fusarium Head Blight in the world, a cereal disease spread throughout the world, reducing grain production and quality. F. graminearum isolates are genetically and phenotypically highly diverse. Notably, remarkable variations of aggressiveness between isolates have been observed, which could reflect an adaptive potential of this pathogen. In this study, we aim to characterize the genetic basis of aggressiveness variation observed in an F1 population, for which genome sequences of both parental strains are available. Aggressiveness was assessed by a panel of in planta and in vitro proxies during two phenotyping trials including, among others, disease severity and mycotoxin accumulation in wheat spike. One major and single QTL was mapped for all the traits measured, on chromosome I, that explained up to 90% of the variance for disease severity. The confidence interval at the QTL spanned 1.2 Mb and contained 428 genes on the reference genome. Of these, four candidates were selected based on the postulate that a non-synonymous mutation affecting protein function was responsible for phenotypic differences. Finally, a mutation was identified and functionally validated in the gene FgVe1, encoding for a velvet protein known to be implicated in pathogenicity and secondary metabolism production in several fungi.