Identification of indole-3-carboxylic acid as mediator of priming against Plectosphaerella cucumerina

► Using the Precursor Ion Scanning in infected plants we found the precursor ion 160 m/z. ► The ion 160.0409 m/z was identified as I3CA using a TOF analyser. ► BABA primes for I3CA accumulation. It may participate in enhancing plant's resistance.