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Identification and characterisation of in-planta expressed Zymoseptoria tritici effectors

Sujit Jung Karki: University College Dublin

<div><em>Zymoseptoria tritici </em>is an ascomycete fungus that causes Septoria Tritici Blotch, an important foliar disease of wheat which can cause up to 50% crop losses. Infection occurs through the stomata, followed by a latent period of 2-3 weeks where <em>Z. tritici </em>remains within the plant apoplast. The fungus then shifts to a necrotrophic phase, resulting in necrosis of the plant tissue corresponding with an increase in fungal biomass. <em>Z. tritici </em>is predicted to produce a series of small secreted proteins (SSPs) throughout its interaction with the host (Rudd <em>et al</em>., 2015). To understand the role of <em>Z. tritici </em>SSPs during infection and host colonisation, We mined publically available data and a second dataset was generated in the lab from <em>Z. tritici</em> infected wheat leaves. Using this information and the NCBI conserved domain search, we identified 50 SSPs with no homology to known proteins. 30 out of 50 SSPs were then cloned into overexpression vectors for transient expression <em>in planta</em>. In order to test these SSPs as potential effectors, the induction of cell death in the non-host model plant <em>Nicotiana benthamiana</em> was tested. We identified 6 prominent effector candidates that resulted in a cell death phenotype. These candidates will then be further characterised for their role in pathogenicity.</p> <p>Reference:</p> <p>Rudd JJ, Kanyuka K, Hassani-Pak K <em>et al</em>. (2015) Transcriptome and metabolite profiling of the infection cycle of <em>Zymoseptoria tritici</em> on wheat reveals a biphasic interaction with plant immunity involving differential pathogen chromosomal contributions and a variation on the hemibiotrophic lifestyle definition. <em>Plant physiology</em> <strong>167</strong>(3): 1158-1185.</p> <p>Marchler-Bauer A <em>et al</em>. (2015) <em>"CDD: NCBI's conserved domain database."</em> Nucleic Acids Res (43)222-6.</div>