Optimisation of tobacco rattle virus-induced gene silencing in Arabidopsis

Arabidopsis thaliana ( L.) Heynh. is a model plant species in which to study plant gene functions. Recently developed virus-induced gene silencing (VIGS) offers a rapid and high-throughput technique platform for gene function analysis. In this paper we report optimisation of tobacco rattle virus (TRV)-induced gene silencing in Arabidopsis. The parameters potentially affecting the efficiency of VIGS in Arabidopsis were investigated. These included the concentration and pre-incubation of Agrobacterium inocula (agro-inocula), the concentration of acetosyringone included in agro-inocula, the Agrobacterium inoculation (agro-inoculation) method, the ecotypes and the growth stages of Arabidopsis plants for agro-inoculation, and the growth temperature of agro-inoculated plants. The optimised VIGS procedure involves preparing the agro-inocula with OD600 of 2.0, pre-incubating for 2 h in infiltration buffer containing 200 mu M acetosyringone, agro-inoculating by vacuum infiltration, and growth of agro-inoculated plants at 22-24 degrees C. Following this procedure consistent and highly efficient VIGS was achieved for the genes encoding phytoene desaturase (PDS) and actin in Arabidopsis. The silencing phenotype lasts for at least 6 weeks, and is applicable in at least seven ecotypes, including Col-0, Cvi-0, Sd, Nd-1, Ws-0, Bay-0 and Ler. TRV-induced VIGS was expressed not only in leaves, but also in stems, inflorescences and siliques. However, VIGS was not transmissible through seed to the subsequent generation. The optimised procedure of the TRV-induced gene silencing should facilitate high-throughput functional analysis of genes in Arabidopsis.