Investigation of HCPro-Mediated Ethylene Synthesis Pathway Through RNA-Seq Approaches

Chilli veinal mottle virus (ChiVMV) severely compromises the quality and yield of solanaceous crops. The helper component protease (HCPro) of ChiVMV functions as a multifunctional RNA silencing suppressor that subverts host antiviral defenses through diverse strategies, However, the underlying mechanisms remain mechanistically unresolved. In this study, HCPro-overexpressing (HCPro-OX) and wild-type (WT) plants were inoculated with ChiVMV to monitor the physiological and molecular changes. Transcriptome analysis identified 11,815 differentially expressed genes (DEGs) under viral infection, among which 1115 genes were specifically regulated by HCPro. KEGG enrichment analysis revealed that the DEGs were significantly associated with plant hormone signal transduction pathways, indicating their crucial role in host-virus interactions. Furthermore, functional clustering of HCPro-regulated DEGs specifically identified key components in ethylene biosynthesis pathways. GO analysis of DEGs between virus-inoculated WT and HCPro-OX plants annotated ethylene biosynthesis-related genes NtACO and NtACS. qPCR validation confirmed that the expression of ethylene biosynthesis-related genes was suppressed by HCPro. Exogenous treatments with the ethylene precursor ACC demonstrated that ethylene suppressed viral accumulation, enhanced POD activity, and reduced the ROS accumulation induced by viral infection. In conclusion, our results demonstrate that HCPro promotes viral infection by suppressing ethylene biosynthesis, which in turn attenuates peroxidase activity, leading to ROS accumulation.