A cerato‐platanin protein SsCP1 targets plant PR1 and contributes to virulence of <i>Sclerotinia sclerotiorum</i>

<jats:title>Summary</jats:title><jats:p> <jats:list list-type="bullet"> <jats:list-item><jats:p>Cerato‐platanin proteins (<jats:styled-content style="fixed-case">CP</jats:styled-content>s), which are secreted by filamentous fungi, are phytotoxic to host plants, but their functions have not been well defined to date.</jats:p></jats:list-item> <jats:list-item><jats:p>Here we characterized a <jats:styled-content style="fixed-case">CP</jats:styled-content> (Ss<jats:styled-content style="fixed-case">CP</jats:styled-content>1) from the necrotrophic phytopathogen <jats:italic>Sclerotinia sclerotiorum</jats:italic>. <jats:italic>Sscp1</jats:italic> transcripts accumulated during plant infection, and deletion of <jats:italic>Sscp1</jats:italic> significantly reduced virulence. Ss<jats:styled-content style="fixed-case">CP</jats:styled-content>1 could induce significant cell death when expressed in <jats:italic>Nicotiana benthamiana</jats:italic>.</jats:p></jats:list-item> <jats:list-item><jats:p>Using yeast two‐hybrid, <jats:styled-content style="fixed-case">GST</jats:styled-content> pull‐down, co‐immunoprecipitation and bimolecular florescence complementation, we found that Ss<jats:styled-content style="fixed-case">CP</jats:styled-content>1 interacts with <jats:styled-content style="fixed-case">PR</jats:styled-content>1 in the apoplast to facilitate infection by <jats:italic>S. sclerotiorum</jats:italic>. Overexpressing <jats:italic><jats:styled-content style="fixed-case">PR</jats:styled-content>1</jats:italic> enhanced resistance to the wild‐type strain, but not to the <jats:italic>Sscp1</jats:italic> knockout strain of <jats:italic>S. sclerotiorum. Sscp1</jats:italic>‐expressing transgenic plants showed increased concentrations of salicylic acid (SA) and higher levels of resistance to several plant pathogens (namely <jats:italic>Botrytis cinerea</jats:italic>,<jats:italic> Alternaria brassicicola</jats:italic> and <jats:italic>Golovinomyces orontii</jats:italic>).</jats:p></jats:list-item> <jats:list-item><jats:p>Our results suggest that Ss<jats:styled-content style="fixed-case">CP</jats:styled-content>1 is important for virulence of <jats:italic>S. sclerotiorum</jats:italic> and that it can be recognized by plants to trigger plant defense responses. Our results also suggest that the <jats:styled-content style="fixed-case">SA</jats:styled-content> signaling pathway is involved in <jats:styled-content style="fixed-case">CP</jats:styled-content>‐mediated plant defense .</jats:p></jats:list-item> </jats:list> </jats:p>