Specific up-regulation of transcription factors in the fungus Parastagonospora nodorum suggests a role in pathogenicity on wheat

The necrotrophic fungus Parastagonospora nodorum, the causal agent of stagonospora nodorum blotch (SNB), is responsible for significant economic losses of wheat worldwide. Despite the presence of a high number of TF-encoding genes within the genome of P. nodorum, very little is known about their expression profile and their functions during cellular and biological processes. In this study, ten putative TF genes in P. nodorum isolate SN15 were selected, four of which shared homology with well-known fungal TFs involved in pathogenesis, and the other six genes were located in putative secondary metabolite biosynthetic gene clusters (BGCs). The expression profile of these candidate TF genes was investigated using both semi-quantitative and quantitative RT-PCR assays under in vitro and in planta conditions. The results revealed that six candidate TF genes exhibited the highest expression levels in the minimal media lacking both nitrogen and carbon sources as well as during the early stages of infection. These findings suggest that these six candidate TFs may play an important role in the pathogenicity of P. nodorum.