Transcript abundance for MYB genes and secondary cell-wall-related genes in differentiating secondary xylem and in primary growth (new flush) of spruce seedlings. Transcript abundance was determined as in Figure 4 for, a) 13 spruce MYB genes, and b) five cell-wall-related genes in differentiating secondary xylem from stem and in the elongating terminal leader (apical stem) from 3-year-old spruce seedlings. The standard error (bars) was calculated from three biological replicates and two independent technical repetitions (i.e. six independent measurements). PAL, phenylalanine ammonia lyase; 4CL, 4-coumarate: CoA ligase; CCOaOMT, caffeoyl-CoA 3-O-methyltransferase; AGP, arabinogalactan protein; CAD, cinnamyl alcohol dehydrogenase. NS, no PCR product detected.