Root uptake, translocation and persistence of EAB-specific dsRNA in ash seedlings

RNA interference (RNAi) is a sequence-specific gene silencing mechanism triggered by double-stranded RNA (dsRNA). Exploiting the RNAi mechanism to silence essential genes in insects has emerged as a promising new pest control strategy, and RNAi-based products are being developed for plant protection. RNAi has proven effective in silencing genes and causing mortality in the highly invasive emerald ash borer (EAB) (Agrilus planipennis) (Coleoptera: Buprestidae); however, a practical delivery method remains a barrier to its deployment. In this study, we evaluate the systemic distribution and retention of exogenously applied dsRNA in green ash (Fraxinus pennsylvanica) tissues to investigate the feasibility of dsRNA delivery through the host plant. To evaluate the distribution and persistence of dsRNA, seedings are exposed to EAB-specific dsRNA as a root soak, sampled 3, 7, 14, 21, and 30 d after exposure, and sectioned into root, woody-stem, soft-stem, and leaf tissues. Total RNA is extracted and evaluated by RT-PCR. Gel images and Sanger sequencing confirm the presence of exogenously applied dsRNAs, demonstrating successful uptake and translocation of dsRNAs throughout plant tissues. Our findings demonstrate that root application represents a viable delivery method for dsRNA in ash seedlings, supporting the potential of this technology in providing ash protection against EAB.