Dissecting the role of early-infection expressed putative transcription factors in the pathogenicity of Parastagonospora nodorum on wheat.

2. Abstract Parastagonospora nodorum is a necrotrophic fungal pathogen that causes Septoria nodorum blotch of wheat. For successful wheat infection, P. nodorum coordinates an intricate assembly of virulence and pathogenicity-associated genes early in its lifecycle. Regulation of these virulent determinant genes is typically under direct control of diverse families of transcription factors (TFs). This study investigated three new putative candidate transcription factors (CTFs) that showed maximal expression during early infection akin to previously characterised virulence-regulating TFs. Through CTF knockout (KO) gene-deletion mutants, we analysed their roles in vegetative morphology and virulence on the wheat cultivar Axe. Each CTF KO mutant exhibited SN15 (wild-type) characteristics in-vitro and were fully virulent on wheat. It is likely that these genes may be redundant or compensated through signalling cross-talks by functionally related TFs during infection, or by some other undiscovered physiological functions not related to host virulence.