Department of Plant, Soil, and Entomological Sciences, University of Idaho, P.O. Box 442339, Moscow, ID 83844, USA; e-mail: [email protected]

The current era of gene inheritance analysis began with the rediscovery in the early 1900s of Gregor Mendel’s 1866 work, Experiments in Plant Hybridization (Mendel 1866). Since then a plethora of plant inheritance studies has occurred, in some of which the trait of interest was simply inherited. In general, for a trait to be defined as simply inherited, a single gene or a tightly grouped cluster of linked genes, inherited as a unit, must be responsible. At a whole plant level, this is revealed by phenotypic segregation ratios among progeny. For any given population structure, simply inherited traits segregate among progeny at expected Mendelian segregation ratios, assuming minimal infl uence by biological or environmental variables. Simply inherited traits typically include those in which a completely dominant phenotype can be qualitatively scored. Potato has many examples of simply inherited traits.