With over 6,000 cultivars from up to 40 species distributed across Asia, Europe and America, it is little wonder that Hedrick, the famous USA pomologist, wrote that plums “give a greater range of flavour, aroma, texture colour, form and size, the qualities that gratify the senses and make fruits desirable, than any other of our orchard fruits”. Indeed plum is recognized to harbor the largest diversity of any Prunus subgenus and represent a link between the major subgenera. Two species account for the majority of modern commercial production: the hexaploid European plum (Prunus domestica L.) and the diploid Japanese plum (P. salicina Lindl and hybrids). A challenge for breeders is how to tap into other plum and related Prunus species to develop new cultivars with broadened adaptation and innovative products. While belonging to same taxonomic section, European and Japanese plums are distinct crops in terms of their uses, adaptation, origin and domestication. They are usually grown in different locations – European plums in cooler areas and Japanese plums in warmer areas. They have distinct cultural and historical backgrounds that have resulted in European plums being dominant in Europe and Japanese plums dominant elsewhere.