Efficient virus-induced gene silencing in Brassica rapa using a turnip yellow mosaic virus vector

Virus-induced gene silencing (VIGS) is a post-transcriptional gene silencing method used for unraveling gene functions. As an attractive alternative to mutant collections or stable transgenic plants, it has been widely used in reverse-genetics studies owing to its ease use and quick turnaround time. Turnip yellow mosaic virus (TYMV) has the ability to induce VIGS in Arabidopsis thaliana. However, the conventional vector construction is difficult and the efficiencies of the infection methods are low. Here, we improved the vector construction and viral infection methods, inserted an inverted-repeat fragment of the phytoene desaturase gene into a TYMV-derived vector by homologous recombination and transformed Brassica rapa with plasmid DNA harboring a cDNA copy of the TYMV genome through particle bombardment. An apparent photobleaching phenotype was detected and efficient VIGS was induced. An 80-bp fragment was sufficient to produce VIGS in leaves, stems, roots, flowers, siliques, and stalks of B. rapa. Because TYMV has a wide host range in Brassica, the VIGS system described here will contribute to the improvement of high-throughput technology and efficient functional research in B. rapa and other Brassicaceae crops.