Grapevine red blotch virus C2 and V2 are suppressors of post-transcriptional gene silencing

Grapevine red blotch virus (GRBV) is the causative agent of grapevine red blotch disease (GRBD) which is one of the major threats faced by grapevine industry in the United States. Since its initial identification in 2011, the disease has rapidly spread in the major US grape-growing regions of the Pacific Northwest, causing major economic impacts. Geminiviruses, the largest family of plant viruses, can induce and be targeted by host post-transcriptional gene-silencing (PTGS) anti-viral mechanisms. As a counter-defense mechanism, viruses have evolved viral silencing suppressor proteins to combat PTGS mechanisms and establish a successful infection in host plants. Here we provide characterization of two ORFs of GRBV, C2 and V2 as viral silencing suppressors. In Nicotiana benthamiana line 16c GFP marker plants, synergism or additive effects of C2 and V2 suppressors was observed at the mRNA level when they are expressed together transiently. Additionally, we showed there is no evidence by yeast two-hybrid of self-interaction (dimerization) of C2 or V2 proteins, and no evidence of physical interaction between these two suppressors.

Automated summary

Grapevine red blotch virus (GRBV) is a major threat to the US grapevine industry since its identification in 2011, causing significant economic impacts in the Pacific Northwest grape-growing regions. This study characterized two ORFs of GRBV, C2 and V2, as viral silencing suppressors, showing synergism or additive effects at the mRNA level when expressed together in Nicotiana benthamiana line 16c GFP marker plants. Furthermore, no self-interaction or physical interaction between C2 and V2 proteins was observed.