Induction of distinct plant cell death programs by secreted proteins from the wheat pathogen Zymoseptoria tritici

Cell death processes in eukaryotes shape normal development and responses to the environment. For plant-microbe interactions, initiation of host cell death plays an important role in determining disease outcomes. Cell death pathways are frequently initiated following detection of pathogen-derived molecules which can lead to resistance or susceptibility to disease depending on pathogen lifestyle. We previously identified several small secreted proteins (SSPs) from the wheat-infecting fungus Zymoseptoria tritici that induce rapid cell death in Nicotiana benthamiana following Agrobacterium-mediated delivery and expression (agroinfiltration). Here we investigated whether the execution of host cells was mechanistically similar in response to different Z. tritici SSPs. Using RNA sequencing, we found that transient expression of four Z. tritici SSPs led to massive transcriptional reprogramming within 48 h of agroinfiltration. We observed that distinct host gene expression profiles were induced dependent on whether cell death occurs in a cell surface immune receptor-dependent or -independent manner. These gene expression profiles involved differential transcriptional networks mediated by WRKY, NAC and MYB transcription factors. In addition, differential expression of genes belonging to different classes of receptor-like proteins and receptor-like kinases was observed. These data suggest that different Z. tritici SSPs trigger differential transcriptional reprogramming in plant cells.