After infection by the super race isolate CN152 of Phytophthora infestans (Pi) in the tetraploid potato genotype SD20, multi-signaling pathways of salicylic acid (SA), jasmonic acid (JA), and ET were involved in resistance and defense against Pi, and one ET synthesis pathway enzyme, 1-aminocyclopropane-1-carboxylate oxidase (ACO), was enhanced in Pi infected potato5. This evidence concerns the gene KLK15 and infection.