Quantitative RT-PCR (qRT-PCR) has been widely used in gene expression analysis because of its sensitivity, specificity, and reproducibility. Application of suitable reference genes to normalize qRT-PCR data is critical in analyzing PCR results. We analyzed the expression patterns of 7 housekeeping genes, including TUA8, TUB6, ubiquitin, GAPDH, actin, 18S rRNA and EF1α, in various tissues of greenhouse-grown Populus trichocarpa and Zn-treated in vitro plantlets. The stability of housekeeping

more »

... expression was analyzed with use of 3 software packages, including geNorm, Norm-Finder, and BestKeeper. The genes actin, ubiquitin, EF1α and 18S rRNA were suitable reference genes for efficient normalization of qRT-PCR data, whereas TUB6 and GAPDH were not suitable for analysis of greenhouse-grown plants and Zn-treated plantlets, respectively. These findings were confirmed by comparative profiling of 4 P. trichocarpa NAC genes. This study provides useful information for reference gene selection in qRT-PCR analysis of gene expression in P. trichocarpa. It is also helpful to elucidate the function of P. trichocarpa NAC genes.