<i>PtrDFR1</i> and <i>PtrDFR2</i> transcript levels in different tissues of <i>P. trichocarpa</i>.

<p>(<b>A</b>) Gel analysis of semiquantitative reverse transcriptase (RT)-PCR with transcript-specific <i>DFR</i> primers. (<b>B</b>) Expression levels were determined by qRT-PCR. Values represent averages of three biological replicates, each with two technical replicates. <i>Actin</i> expression of poplar was used as a control. Total RNA was isolated from poplar tissues: root (R), shoot (S), young leaf (YL), old leaf (OL), young petiole (YP) and old petiole (OP).