Description
Plant viruses induce various disease symptoms, but their underlying mechanisms are poorly understood. Kobu-sho is a disease in gentian that show gall formation with ectopic development of lignified cells and vascular tissues such as xylem. Recently, we identified a novel unusual RNA virus, gentian Kobu-sho-associated virus (GKaV) from Kobu-sho-affected gentian. Here, we show that a gene fragment of GKaV, Kobu-sho-inducing factor (KOBU), induces gall formation accompanied with ectopic development of lignified cells and xylem-like tissue in Nicotiana benthamiana. We identify KOBU by screening using potato virus X vector in N. benthamiana, and confirm that transgenic gentian expressing KOBU causes tumorous symptom.