Population stratification based on Bayesian clustering approaches for K = 1 to K = 10 (Each individual is shown as a thin vertical line, different subpopulations are separated by a black line and are in different colors). a The first STRUCTURE step with 658 accessions, when K = 3. The subpopulation was displayed by DISTRUCT. Each subpopulation was ordered according to the membership coefficient. b Nested STRUCTURE analysis for the Oriental subpopulation which was further divided into two subpopulations: ‘Yu Lu’ and ‘Hakuho’. c Nested STRUCTURE analysis for the Occidental breeding subpopulation, mainly divided into ‘Nectarine’ and ‘Peach’ populations. d Nested STRUCTURE analysis for the landrace subpopulation. Note: Unstructured indicates the individuals which were not assigned to any subpopulation. The characters and numbers at the top of each population column give the name of each subpopulation and the number of individuals included.