The transgenic potato lines SEMT15-02 and SEMT15-15 were produced using recombinant DNA techniques and contain two novel genes, whose individual expression results in resistance to attack by Colorado potato beetle (CPB; Leptinotarsa decemlineata) and resistance to infection by Potato Virus Y strain O (PVY-O). Resistance to attack by CPB was accomplished by introducing the cry3A gene from Bacillus thuringiensis subsp. tenebrionis, which encodes an insecticidal crystalline Cry3A delta-endotoxin protein. The insecticidal activity of Cry3A protein is due to its selective binding to specific sites localized on the brush border midgut epithelium of susceptible insect species. Following binding, cation-specific pores are formed that disrupt midgut ion flow and thereby cause gut paralysis, ultimately leading to bacterial sepsis and death. Delta-endotoxins, such as the Cry3A protein expressed in CPB resistant potato lines, exhibit highly selective insecticidal activity against a narrow range of coleopteran insects such as CPB, elm leaf beetle and yellow mealworm. Their specificity of action is directly attributable to the presence of specific receptors in the target insects. There are no receptors for delta-endotoxins of B. thuringiensis on the surface of mammalian intestinal cells, therefore, livestock animals and humans are not susceptible to these proteins.

Pathogen-derived resistance to PVY was conferred by introducing the coat protein (CP) gene from PVY-O. The coat protein forms a protective coat around the RNA genome of the virus and comprises 95% by mass of the virus particle. Although the exact mechanism is not fully understood, these transgenic potato lines exhibit resistance to infection and subsequent disease caused by PVY through a process that is related to viral cross-protection.