Fig. 3

Model-based populations in association panels consisting of 292 USDA GRIN spinach germplasm accessions: a Delta K values for different numbers of populations (K) assumed in the analysis completed with the STRUCTURE software. b Classification of 292 spinach accessions into four populations using STRUCTURE Version 2.3.4, where the numbers on the y-axis show the subgroup membership, and the x-axis shows the different accession. The distribution of accessions into different populations is indicated by the color coding and shape (Cluster 1, Q1, is red round shape; Cluster 2, Q2, is the green triangle; Cluster 3, Q3, is the blue triangle; Cluster 4, and Q4, is yellow diamond). c Maximum Likelihood (ML) tree of the 292 spinach accessions drawn by MEGA 6. The color code for each population is consistent with (b) and (c), and the empty black square represents accessions aligned with the admixture cluster or population in 292 USDA GRIN spinach germplasm accessions