Comparison of tissue-specific expression patterns of <i>NRT</i> genes in <i>P. trichocarpa</i> (Ptri) and <i>P. tremula</i> (Ptre).

<p>The heatmap represents the hierarchical clustering of average log₂(relative expression) of <i>NRT</i> genes in stem top (T), bark (B), developing xylem (DX), leaves (L), wood (W), and roots (R). The color of the gene name represents the clade in the phylogenetic tree (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0072126#pone-0072126-g001" target="_blank">Figure 1</a>).