(A) Positions of the RNAi target sequence in the GAUT12.1 (POPTR_0001s44250/Potri.001G416800) gene. Blue boxes indicate exons, lines indicate introns, and gray boxes are the 5′ and 3′ untranslated regions (UTRs). The RNAi target sequence was 168 bp in the 3′UTR. The arrows indicate the targeted sequences used for quantitative real-time PCR. (B) Schematic presentation of PdGAUT12.1 RNAi silencing construct. (C) Quantitative real-time PCR analysis of controls and PdGAUT12.1-KD lines of 3-month-old plants. The relative expression level of each gene was normalized using Populus 18S ribosomal RNA (18S rRNA) as the reference gene and the expression of PdGAUT12.2 in AB30.5 was set to 1. N = 5. Error bars represent SE.