Phenylpropanoid Metabolites Mediate Antiviral Defense and Vector Resistance in Rice Infected With RRSV, RGSV, and SRBSDV

Rice viruses frequently cause major yield losses, threatening global food security. In this study, we employed a multi-omics approach (transcriptome, small RNA and metabolome) to investigate the common and distinct responses of rice to three dwarfing viruses, rice ragged stunt virus, rice grassy stunt virus and Southern rice black-streaked dwarf virus. All three pathogens elicited notable dwarfing and increased tillering in infected plants, which significantly impacted yield potential. We identified thousands of DEGs and metabolites, revealing significant accumulation of phenylpropanoid intermediates, such as ferulic acid (FA) and cinnamic acid (CA). Despite the downregulation of lignin biosynthesis genes, total lignin content rose markedly, which indicated a feedback regulation mechanism that reinforced cell walls. Hormone signalling pathways were also reprogrammed, with elevated jasmonic acid (JA) and suppressed ethylene and abscisic acid pathways, which potentially weakened certain defences. Exogenous application of FA and CA effectively promoted lignin deposition and exerted a degree of inhibition on brown planthopper feeding. These findings highlighted the phenylpropanoid pathway as a critical nexus that linked plant structural reinforcement and defence responses. Our study provided novel targets for breeding virus-resistant rice cultivars and offered a broader framework for understanding plant-pathogen-insect interactions.