The USDA-ARS Potato Variety Development for the Eastern US breeding program is based in Orono and Presque Isle, Maine. While tetraploid potato breeding for the chipper and table markets is the primary focus of the breeding program, this program has included diploid potato breeding projects since at least 1987. The majority of the diploid germplasm was derived from a population of Solanum tuberosum Group Phureja and Solanum stenotomum. This population has been under selection for long-day adaptation for many decades and has been demonstrated to be a source of disease resistance. Additional diploid breeding clones from AAFC, Michigan State, and University of Maine have been included in diploid crossing efforts. Dihaploids developed through the Potato 2.0 project have also been included in the latest round of diploid potato crosses. A selection of diploid breeding clones have been pollinated with inducer pollen and monoploid potato clones have been identified from these crosses. The University of Maine is currently in the process of doubling these monoploids to develop fully inbred diploid breeding clones. Doubled monoploids may provide a shortcut to the laborious process of developing inbreds through selfing.
