Protection against Beet mosaic virus via topical application of dsRNA.

Abstract

Beet mosaic virus (BtMV), a Potyvirus found worldwide capable of causing reduction in sugar yield, was studied because of its frequent and synergistic interactions with the virus complex that comprises Virus Yellows, an important disease of sugar beet. Facing potential regulations for current management strategies for this disease, there is an increasing need for environmentally friendly new age pesticides to manage Virus Yellows and other important insect-vectored viruses of sugar beet. Here, double stranded RNA (dsRNA) was studied as an alternative control strategy by employing RNA interference (RNAi) to inhibit virus replication in sugar beet and Chenopodium quinoa. DsRNA targeting the BtMV 5’ UTR, 3’ UTR, and virus coat protein were constructed and tested as targets to disrupt viral replication and infection. In all experimental replicates in C. quinoa as a local lesion host, negative and nonspecific dsRNA control treatments resulted in severe infection indicated by a high number of lesions. In contrast, inoculated C. quinoa treated with a low dose of dsRNA (100 pmol) specific to the BtMV 5’ UTR, 3’ UTR, and coat protein demonstrated a reduction in local lesions up to 98.8%, 95.7%, and 94.1%, respectively. Lower quantities of dsRNA were tested with a slight decrease in control indicating that control is dose dependent. Interestingly, BtMV was found to translocate systemically in C. quinoa, a characteristic previously unreported for this virus. Systemic infection in otherwise protected C. quinoa may indicate that mobile RNAi is required for full plant protection in this pathosystem. Time course and dose dsRNA studies will be discussed. Preliminary results suggest that dsRNA has potential as a disease management strategy for Virus Yellows.