Mechanism of plant-derived antiviral agent eugenol against tobacco mosaic virus disease in tobacco

Eugenol is a novel plant-derived antiviral agent.To study the mechanism of eugenol-induced resistance in tobacco leaves against TMV(tobacco mosaic virus) infection,the effects of eugenol on TMV replication and SA(salicylic acid) signaling pathway in tobacco leaves was investigated with pot experiment.The treatment with eugenol at concentration of 400 μg / ml showed significantly protective and therapeutic effects on TMV disease,with the efficacies of 65.82% and 62.14%,respectively.Eugenol treatment inhibited the expressions of RdRp and CP,which are two key genes for TMV replication,and was able to induceoxidative burstin tobacco leaves represented by the remarkable accumulation of reactive oxygen species such as superoxide anion radical(O 2 ·-) and hydrogen peroxide(H 2 O 2).In tobacco leaves,eugenol treatment significantly stimulated the generation of SA,and the transcription of NPR1,a key regulative gene in SA signaling pathway.It is suggested that eugenol-inhibited TMV replication may result from the induction of systemic acquired resistance(SAR) by activating SA signaling pathway in tobacco leaves.