Integrating cotyledon-based virus-induced gene silencing with visual marker promises a rapid, highly effective validation of gene functions in .

spp. generate volatile nepetalactone iridoids that have cat-attractant and insect-repellent activities. They differ from typical mint family (Lamiaceae) iridoids, which are non-volatile glucosides, and also vary from other species in the Nepetoideae sub-family, which do not generate iridoids. The chemistry and evolution of make it suitable for further investigation. However, the lack of transgenic technology hampers the molecular and genetic investigations in . Virus-induced gene silencing (VIGS) is a powerful tool to detect gene functions . Here, we constructed a modified VIGS method in , using cotyledon infiltration, with the gene silencing effect spreading to the first two pairs of true leaves. The VIGS efficiency reached as high as 84.4%, and the procedure takes only 3 weeks. We employed this method to validate the role of geraniol 8-hydroxylase in nepetalactone biosynthesis with as a visual marker in . The method is also applicable to . Thus, we developed an easy and effective VIGS approach, which will be advantageous for endogenous gene studies in two species and holds the potential for application in other plants.