The higher expression levels of dehydroascorbate reductase and glutathione reductase in salicylic acid-deficient plants may contribute to their alleviated symptom infected with RNA viruses.

Salicylic acid (SA) is a critical signal for activation of both local and systemic resistance responses. However, SA-deficient plants adapt to RNA virus infections better, which show a less-severe symptom and less reactive oxygen species (ROS) accumulation. The higher levels of reduced glutathione (GSH) and reduced ascorbic acid (AsA) in SA-deficient plants may contribute to their alleviated symptoms, which are consistent with their higher expression levels of dehydroascorbate reductase gene (DHAR) and glutathione reductase gene (GR). High-dose AsA or GSH treatment could alleviate the symptom and inhibit virus replication after 20 days, but ROS eliminators could not imitate the effect of AsA or GSH. The data show a new link between SA and AsA/GSH-mediated redox homeostasis.