Fig. 4

K-means clustering of genes differentially expressed between four sub-apical internodes of bioenergy sorghum inbred R.07020. Genes differentially expressed between at least any two of the four successive sub-apical internodes (Int1–Int4) were grouped into six clusters. Int1 is the youngest sub-apical and Int4 is the oldest internode. Expression level of each gene/transcript in RPKM was normalized prior clustering. Data are mean RPKM of three biological replicates. Bars represent standard deviation (SD)