Fig. 1

Geographic distribution, phylogeny and population structure of melon accessions. a Geographical distribution of the 2083 melon accessions in the U.S. National Plant Germplasm System (NPGS). The circle size indicates the relative sampling number from each region. b Rooted maximum-likelihood phylogenetic tree of the 2083 melon accessions. Gray and black branch colors indicate the ssp. agrestis and the ssp. melo, respectively. Three cucumber accessions whose sequence data were downloaded from NCBI SRA (SRR543204, SRR543227 and SRR543228) were used as the outgroup. c Model-based clustering with K from 2 to 5. The colors and length of vertical bars represent different ancestral populations and the relative contributions in each of the 2083 melon accessions. The gray and black bars indicate ssp. agrestis and ssp. melo, respectively. d Principal component analysis (PCA) of the 2083 melon accessions with PC1 and PC2 explaining 13.8 and 4.1% of variance, respectively