Pyrazolecarboxylic acid derivative induces systemic acquired resistance in tobacco

Systemic acquired resistance (SAR) is a potent innate immunity system in plants that is induced through a salicylic acid (SA)-mediated pathway. Here, we characterized 3-chloro-1-methyl-1H-pyrazole-5-carboxylic acid (CMPA) as an effective SAR inducer in tobacco. Soil drench application of CMPA induced PR gene expression and a broad range of disease resistance without antibacterial activity in tobacco. Both analysis of CMPA's effects on NahG transgenic tobacco plants and SA measurement in wild-type plants indicated that CMPA-induced resistance enhancement does not require SA. Therefore, it is suggested that CMPA induces SAR by triggering the signaling at the same level as or downstream of SA accumulation as do both benzo(1,2,3)thiadiazole-7-carbothioic acid S-methyl ester and N-cyanomethyl-2-chloroisonicotinamide.