The potential benefits of plant genetic engineering for disease and pest resistance have been widely acknowledged in many studies, and although genetically modified crops are still encountering public wariness, these benefits warrant continued exploration. Because of its intrinsic economic benefits, the development of true potato seed (TPS) cropping systems has been instituted in many regions of the world. The incorporation of transgenic resistance could further the economic gain of farmers who are seeking ways to sustain their livelihood in the most efficient way possible. It is, however, largely unresearched how sexual hybridization of a transgenic crop would affect the behavior of a transgene in the resultant progeny. In the initial part of this study, transgenic lines were developed with a Cry3Aa transgene. These plants were then used in 4x-4x reciprocal crosses and 4x-2x hybridization schemes to determine the stability of the transgene after sexual hybridization. There was no observed parent of origin effect on transgene expression; however, a highly significant, non-mendelian inheritance of the Cry3Aa transgene was seen in the maternally inherited transgene of one set of progeny from a reciprocal cross. Additional transgenic lines of potato were developed with a PVY-O coat protein transgene. These plants were challenged with PVY-O and monitored for symptoms visually and for virus serologically. One transgenic line exhibited complete resistance to PVY-O while two others showed a delay in symptom occurrence. Further examination of the expression levels of the PVY-O coat protein transgene will be necessary to determine the type and usefulness of the observed resistance. / Master of Science