Fig. 3: Expression patterns of PdRR8 and PdFERR.

a qRT-PCR analyses of PdRR8 and PdFERR in different tissues of poplar. Tf1 and Tf2 represent female floral buds sampled at the end of June and mid-August, respectively. Tm1 and Tm2 represent male floral buds sampled at the end of June and mid-August, respectively. Ubiquitin gene was used as an internal control. Error bars indicate the mean values (±SD) of three replicates. Bars with distinct letters are significantly different at P < 0.05 level applying Tukey’s HSD multiple comparison test. b Promoter activity analysis in transgenic tobacco. Schematic of the promoter::GUS vectors are shown on the top panel, and GUS histochemical staining of different tissues from the wild type and transgenic tobacco plants are shown on the bottom panel. c and d GUS staining of leaf disks from the wild type and transgenic tobacco plants under various external stimuli. Scale bars represent 5 mm.