Insights from controlled, comparative experiments highlight the limitations of using BSMV and FoMV for virus-enabled reverse genetics in rice

Virus-enabled reverse genetics (VERG) is a powerful tool for transient gene expression modulation in plants, particularly where stable transformation is challenging. However, the efficacy of VERG varies across species. In this study, we tested two commonly used viral vectors, barley stripe mosaic virus (BSMV) and foxtail mosaic virus (FoMV), for their ability to induce virus-induced gene silencing (VIGS) and virus-mediated overexpression (VOX) in rice (Oryza sativa L.). While both vectors successfully altered gene expression in wheat (Triticum aestivum), they failed to do so in six rice cultivars from different subspecies, despite rigorous optimization of inoculation methods and environmental conditions. The BSMV vector carrying antisense phytoene desaturase (PDS) sequences did not induce the expected photobleaching phenotype, and FoMV-driven GFP expression was absent in rice. These findings contrast with previous reports of successful VERG in other monocots and suggest that intrinsic resistance mechanisms exist in rice which may inhibit or reduce viral vector efficacy. Our results highlight the species-specific limitations of VERG and underscore the need for alternative viral systems or novel vector designs for functional genomics research in rice. By sharing our unsuccessful attempts, we aim to prevent redundant efforts and encourage further exploration of VERG in Oryza species.