Multi-omics analysis reveals the defense response in Panax notoginseng against viruses

Panax notoginseng is a traditional medicine plant in China, but viral diseases seriously affect the yield and quality of P. notoginseng medicinal herbs. There are few reports describing the molecular mechanisms underlying P. notoginseng defense responses to viral infection, and this study aimed to obtain new insights into defense mechanism against viruses through a comprehensive multi-omics analysis. Transcriptome and proteome data showed that MAPK signaling and an ROS burst were activated in response to viral infection. Quantitative PCR confirmed that MPK and SRK expression levels were 2.71- and 13.27-fold higher in chlorotic P. notoginseng than in control, respectively. The expression of respiratory burst oxidase homolog protein D in chlorotic P. notoginseng increased by 13.33-fold compared with the control. Simultaneously, the antioxidant enzymes were also activated, and especially, the gene/protein expression levels of SOD in chlorotic P. notoginseng were 15.08/1.97-fold higher than the control. Moreover, many upregulated genes and metabolites were significantly enriched in flavonoid biosynthesis pathways. In contrast, lots of downregulated genes and proteins were mainly associated with photosynthesis and fatty acid metabolism. In addition, viral infection activated the salicylic acid signaling pathway in P. notoginseng, the overexpression of PnEDS1 in P. notoginseng and tobacco enhanced resistance to virus. Our findings provided novel insights into the defense responses in P. notoginseng against viruses.