Fig. 2. Population structure analysis of a Hydrangea macrophylla cultivar panel based on 5803 SNPs developed by GBS.

Each individual is represented by a vertical bar, reflecting assignment probabilities to each of the three groups. Group I: green bars; group II: blue bars; group III: red bars. a Phylogenetic tree based on the neighbor-joining method in MEGA 7; b plot of ΔK value with K from 2 to 10 based on Evanno test; c population structure based on mixed-model analysis using STRUCTURE software. Phylogenetic studies corresponded to population structure groups. ssp. serrata (coded as green) agreed with group I, ssp. macrophylla separated into two clades (colored as blue and red) and corresponded to group II and group III, respectively