A glycine rich protein (NbRBGA) confers broad-spectrum tolerance to begomovirus-betasatellite complex through activation of salicylic acid signalling pathway.

Begomoviruses, the largest genus of the family Geminiviridiae, are ssDNA viruses transmitted by whiteflies. Betasatellite molecules are occasionally found to be associated with begomoviruses and greatly influence viral pathogenesis. During viral invasion, plants activate a well-coordinated antiviral immune response to inhibit the propagation of the pathogen. In this study, we have reported an RNA-binding glycine-rich protein (RBGA) getting differentially expressed during infection due to begomovirus-betasatellite complex in Nicotiana benthamiana. Over-expression of the protein successfully restricts the viral accumulation in both local and systemic leaves. On the other hand, when RBGA was silenced, aggravated symptoms and higher viral titre were observed suggesting it as an anti-viral host factor. Over-expression of RBGA promotes the accumulation of reactive oxygen species (ROS) followed by induction of cell death. In addition, RBGA also activates salicylic acid (SA) signaling and exogenous application of SA was found to reduce viral titre and impede disease development. We further demonstrated that the C- terminal tail containing multiple repeats of a novel motif "GGYGGG" is crucial for the antiviral activity of RBGA. In summary, we have identified a begomovirus inducible glycine-rich protein and delineated its role in conferring anti-viral immune response in the case of plant-infecting DNA viruses for the first time.