Functional characterization of post-transcriptional gene silencing suppressors and effects of mixed infection in okra enation leaf curl virus.

UNLABELLED: Okra enation leaf curl virus (OELCuV) is a monopartite begomovirus, frequently detected in mixed infections in okra, together with bhendi yellow vein mosaic virus (BYVMV) and/or its associated betasatellite. Such mixed infections often lead to synergistic relationships that can intensify disease severity and consequently reduce crop productivity. This study investigated the infectivity of OELCuV and its alphasatellite and evaluated their infection dynamics when co-inoculated with BYVMV and/or its betasatellite. Mixed infections resulted in higher virus accumulation compared to single infections, indicating potential synergism between the two okra-infecting begomoviruses. To identify RNA silencing suppressors of OELCuV, transient expression assays were carried out in 16c/GFPi transgenic line as well as using GFP as a reporter protein. The results revealed that multiple viral proteins, including Rep, C2, C4, C5, and V2, act as suppressors of post-transcriptional gene silencing. The presence of multiple suppressor proteins in OELCuV, together with those encoded by BYVMV, likely enhances the ability of the virus complex to counteract host antiviral defences mediated by RNA silencing. By combining symptom analysis, quantitative assessment of viral DNA accumulation, and functional characterization of viral silencing suppressors, this study provides novel insights into the mechanistic basis of OELCuV-associated disease development. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13337-026-00965-x.