Denis currently leads the Teagasc potato breeding program He holds a first class honours degree from UCD in Industrial Microbiology and a Ph.D. from the department of Botany UCD based on the epidemiology of Irish populations of Late blight (Phytophthora infestans) on potatoes. He has worked as a plant pathologist at Syngenta, Jealotts Hill UK, leading a team on development of new fungicide products for cereals, grape and potato. He joined Teagasc as potato breeder in 2002 and has released eighteen new commercial potato varieties. His research interests include the application of molecular markers in conventional breeding for disease resistance to late blight and potato cyst nematodes, and developing seed potato systems in Sub-Saharan Africa. He also leads a group investigating heavy metal uptake in potato.