Investigating antiviral activities of iodine-conjugated organic agents against major viruses infecting pepper in Korea

Background Plant viruses cause economic losses by reducing the quantity and quality of major crops. This issue is a growing concern due to the expansion of global trade and climate change. In addition, the emergence of new pathogen strains increases the difficulty of controlling viral diseases. Effective management strategies are therefore needed. The control strategy for viral diseases relies primarily on non-chemical and cultural practices, as no commercial viricides are currently available. Some compounds have been identified as effective against certain viruses, but their use in the field is limited due to issues such as concentration, toxicity, and efficacy. Therefore, it is imperative to discover novel antiviral agents that address the existing challenges associated with the identified antiviral candidate compounds. Results In this study, we evaluated iodine-conjugated organic compounds mixed with sialic acid, whey, and blood meal for virus disease management against seven viruses that cause significant yield losses and economic damage to plants. The candidate compounds reduced virus accumulation and symptom development. Treatment with candidate compounds, A4 and A5, reduced viral RNA accumulation to about half that of those in the control group and showed reduced symptoms along with healthier growth. In addition, we performed transcriptome analysis of treatment with two viruses, which suggested that the mechanism of viral RNA replication inhibition might relate to plant defense systems based on phytohormone pathways. Conclusions This study demonstrated that treatments with naturally derived materials, such as iodine, nitrogen, and sialic acid-conjugated organic substances, may directly or indirectly impact the host plant's resistance to various virus infections. Moreover, our findings suggest that these natural candidate materials could be utilized for managing virus diseases in the field. Graphical Abstract