Thiadiazole carboxylic acid moiety of tiadinil, SV-03, induces systemic acquired resistance in tobacco without salicylic acid accumulation

Systemic acquired resistance (SAR) is a potent innate immunity system in plants that is effective against a broad range of pathogens and induced through the salicylic acid (SA)-mediated pathway. Here we have characterized the SAR induction activity of 4-methyl-1,2,3-thiadiazole-5-carboxylic acid (SV-03) identified as a metabolite of tiadinil in rice. Soil drench application of SV-03 induces a broad range of disease resistance and PR gene expression in tobacco. Further analyses using NahG transgenic tobacco plants indicate that SV-03-induced resistance enhancement does not require SA. Therefore, it is suggested that SV-03 induced SAR by triggering signaling at the same level as or downstream of SA accumulation. (c) Pesticide Science Society of Japan.