International Symposium on Cereal Leaf Blights 2019 | University College Dublin, Ireland | 22-24 May 2019

Screening of small secreted proteins of Ztritici reveals a candidate protein that interacts with host ubiquitin system

Angela Feechan
School of Agriculture and Food Science, University College Dublin

Sujit Jung Karki*
School of Agriculture and Food Science, University College Dublin

Oral Presentation
Host-Pathogen Interactions

Moore Auditorium, UCD O'Brien centre for Science
23 May 2019, 14:20

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Septoria Tritici Blotch, caused by the ascomycete fungus Zymoseptoria tritici, is a major threat to wheat production worldwide. The Z. tritici genome encodes for many small secreted proteins (ZtSSP) that likely play a key role in the successful colonisation of host tissues. In this study, we screened thirty of these ZtSSP for the induction of cell death in the non-host model plant Nicotiana benthamiana. We identified five novel candidates that resulted in the rapid accumulation of H2O2 and cell death. Transient overexpression of these five candidates also resulted in the upregulation of defense marker genes in N. benthamiana. These five candidates were further tested for cell death induction in the host wheat. However, our assay showed that none of these induce cell death in wheat, which might suggest host specificity of ZtSSP function and lack of recognition in the host. Additionally, yeast two-hybrid assay using one of the cell death-inducing candidate ZtSSP2 showed that it interacts with wheat E3 ubiquitin ligase in yeast and in planta. Expression analysis of wheat ubiquitin ligase suggests that wheat infected Z. tritici plants showed significant downregulation of TaE3UBQ expression at specific time points (4 dpi and 21 dpi) suggesting its potential role in regulating defense signaling during the wheat-Z. tritici interaction.