BIOLOGICAL INDUCTION OF SYSTEMIC ACQUIRED-RESISTANCE IN ARABIDOPSIS

Previously, Arabidopsis was shown to develop acquired resistance to a bacterial and a fungal pathogen following treatment with the activator compound 2,6-dichloroiso-nicotinic acid (INA). In this study, we show that a necrotizing pathogen, turnip crinkle virus (TCV), can induce s ystemic acquired resistance (SAR) in Arabidopsis against bacterial (Ps eudomonas syringae) and viral (TCV) pathogens. The TCV-induced resista nce results in both a decrease in visible disease symptoms and a reduc tion in the growth of the challenge pathogen. Levels of salicylic acid (SA), a likely endogenous signal for SAR, increased more than fivefol d in response to TCV infection. In addition, exogenously applied SA in duced resistance to the fungal pathogen Peronospora parasitica. Three genes induced to high levels by SA (PR-l, PR-2, and PR-5) were also in duced by TCV inoculation. In addition, we show that INA treatment indu ces resistance to TCV, extending the previous observation of chemicall y induced resistance against bacterial and fungal pathogens to include protection against viral pathogens.