Trigger and suppression of antiviral defenses by grapevine Pinot gris virus (GPGV): novel insights into virus-host interaction.

Grapevine Pinot gris virus (GPGV) is an emerging trichovirus that has been putatively associatedwith a novel grapevine disease known as grapevine leaf mottling and deformation (GLMD). Yet the role ofGPGV inGLMD disease is poorly understood, since it has been detected both in symptomatic and symptomless grapevines. Weexploited a recently constructed GPGV infectious clone (pRI::GPGV-vir) to induce an antiviral response in Nicotiana benthamiana plants. In silico prediction of virus-derived small interfering RNAs and gene expression analyses revealed the involvement of DCL4, AGO5, and RDR6 genes during GPGV infection, suggesting the activation of the posttranscriptional gene-silencing (PTGS) pathway as a plant antiviral defense. PTGS suppression assays in transgenic N. benthamiana 16c plants revealed the ability of the GPGV coat protein to suppress RNA silencing. This work provides novel insights on the interaction betweenGPGV and its host, revealing the ability of the virus to trigger and suppress antiviral RNA silencing.