Fig. 6

Hierarchical clustering reveals a complex pattern of cell wall gene expression in maize stem tissue. Transcript levels in rind tissues from internodes 2–9 were normalized and grouped by hierarchical clustering. Thirteen subclades were grouped into five distinct patterns representing an Elongation (Elong) stage, two transitional (Trans1 and Trans2) stages, a secondary wall development (Sec) stage, and an Early and Late (E&L) stage. Genes comprising these clusters are colored by ratio of Transitional/Secondary wall stages (Internodes 5 through 3) to Elongation stages (Internodes 8 and 9). Genes with expression ratios ≤1.04 are in blue, ratios between 1.05 and 1.94 in green, and ratios ≥1.95 in red