A simple and effective VIGS system facilitates the control of citrus canker by silencing CsLOB1

Virus-induced gene silencing (VIGS) is a powerful technology for molecular characterization of gene functions in plants and has the potential to prevent and control plant diseases. Unfortunately, VIGS in many woody perennials such as citrus are severely hindered because they have a long juvenile period and are recalcitrant to infection compared to herbaceous plants. Here, we report the development of a simple and effective VIGS system based on citrus leaf blotch virus (CLBV), a virus endemic in most citrus-producing countries but showing no symptoms in most citrus varieties. By Agrobacterium-mediated vacuum-infiltration (AVI), pCLBV201-su245 and pCLBV201-pds391 triggered efficient gene silencing (85%) and silencing phenotypes began to appear at 30 days post infiltration/inoculation (dpi), a similar period for achieving that on herbaceous plants. Moreover, the silencing phenotypes could still be observed four years post inoculation. Further, pCLBV201-lob369 was constructed to silence the gene lateral organ boundaries1 (lob1), encoding a key factor for susceptibility to citrus canker that caused by Xanthomonas citri ssp. citri (Xcc). The resistance evaluation results showed that the lesion area, disease index, and bacterial content in the pCLBV201-lob369 treatment group were decreased by 64%, 14%, and 67%, respectively. This work provides a simple and effective VIGS system for citrus which has the potential to be used for diseases control.