Hierarchical cluster analysis and heatmap of volatiles and breeding lines. On the volatile dendrogram (at left) are indicated the clusters obtained: C1-C12. The order of the volatile in the dendrogram corresponds to the one indicated in Additional file 1: Table S1. The upper dendrogram corresponds to genotypes where the sample clusters are indicated by S1-S9. Data are expressed as a log2 of a ratio (sample/common reference). The scale used is indicated below the heatmap.