Fig. 1

Geographic location and population structure of 5056 elite trees selected for the Swedish breeding program. a Map (top) of geographic location of plus trees using the known original location for 2779 trees and predicted location of 2277 trees and b PCA results (bottom) of all 5056 individuals colored by cluster groups. For the group without original location information, we used predicted group information; thus, the size of the dot represents the number of individuals in those groups. The different genetic clusters (Carpathian, red, ROM; Alpine, light blue, ALP; Central Europe, green, CEU; Northern Poland, light plink, NPL; Russia-Baltic, orange, Rus-Bal; central and southern Sweden, dodger blue, CSE; Fennoscandia, forest green, NFE). The detail of the number of seven groups was shown in Additional file 1: Table S1. The materials (type) used for GWAS were located in three common gardens (red circles), in which three wood quality traits and budburst stage (BB) were measured directly, two field half-sib plantations (red triangles), in which FD were scored directly, and the materials used for SNP replication/validation were located in two full-sib progeny field plantations in northern Sweden and three full-sib progeny field plantations in southern Sweden (red plus). The field plantations with growth traits are shown in Additional file 2: Figure S12