Gregor Mendel’s experiments on the pea are all the more remarkable in hindsight for the absence of linkage among the phenotypic traits that were studied. Ever since, analysis of co-inheritance of traits (linkage) from one generation to the next has formed the basis of classical and modern genetics. Linkage analysis has progressed from studies on linkage among phenotypic traits to analysis of linkage among specifi c DNA sequences, resulting in increasingly dense linkage maps. Linkage mapping based on molecular markers has subsequently enabled elucidation of the complete genome sequence of multiple plant species, and genome sequencing of many more, including potato is currently underway.