Two Novel Dimorphism-Related Virulence Factors of Zymoseptoria tritici Identified Using Agrobacterium-Mediated Insertional Mutagenesis

Abstract

Diseases caused by dimorphic phytopathogenic and systemic dimorphic fungi have markedly increased in prevalence in the last decades, and understanding the morphogenic transition to the virulent state might yield novel means of controlling dimorphic fungi. The dimorphic fungus Z. tritici causes significant economic impact on wheat production, and yet the regulation of the dimorphic switch, a key first step in successful plant colonization, is still largely unexplored in this fungus. The fungus is amenable to suppression by fungicides at this switch point, and the identification of the factors controlling the dimorphic switch provides a potential source of novel targets to control Septoria tritici blotch (STB). Inhibition of the dimorphic switch can potentially prevent penetration and avoid any damage to the host plant. The aim of the current work was to unveil genetic determinants of the dimorphic transition in Z. tritici by using a forward genetics strategy. Using this approach, we unveiled two novel factors involved in the switch to the pathogenic state and used reverse genetics and complementation to confirm the role of the novel virulence factors and further gained insight into the role of these genes, using transcriptome analysis via RNA-Seq. The transcriptomes generated potentially contain key determinants of the dimorphic transition.