Virus-induced gene silencing (VIGS) is a genetic tool used to assess gene function.Tobacco rattle virus (TRV) is a VIGS vector commonly used to induce endogenous gene silencing in plants.However,there is no VIGS system established for Centaurea spp.We evaluated the effectiveness of a TRY-based VIGS system using phytoene desaturase (PDS) as a reporter gene in Centaurea cyanus.Three methods including pressure-,vacuum-and apical meristem-infiltration were tested to infect C.cyanas seedlings.Photobleached leaves were only obtained using apical meristem-infiltration after a 14 d treatment.The CcPDS transcripts in photobleached leaves were significantly reduced compared with that in green leaves treated with empty TRV.Four C.cyanus cultivars were tested to detect their VIGS responses,and 'Dwarf Tom Pouce Blue' was the most sensitive.The agro-infiltration condition was optimized by screening for the optimal seedling stage as well as the optimum Agrobacteriurn density for efficient silencing.Seedlings with four true leaves and infiltration with an Agrobacteriurn density of OD600 0.5 were optimal conditions to obtain more photobleached leaves and more intense photobleached phenotype.The results demonstrated the feasibility of TRY-based VIGS for functional analysis of genes in C.cyanus.