Figure 5

Spatial distribution of GS gene expression in poplar trees. Total RNA was extracted from different organs of 2-month-old hybrid poplar. A, meristematic apex. A1, A2 and A3, aerial sections from the top to the bottom of tree. L, leaf lamina. V, veins. P, petiole. S, stem. R1, primary root. R2, secondary root masses. Transcript levels of PtGS1.1, PtGS1.2, PtGS1.3 and PtGS2 were determined by real-time qPCR analysis as described. Expression levels are presented as relative values to reference genes (actin2 and ubiquitin). The histograms represent the mean values of three independent experiments with standard deviations.