Selection of reference genes for RT-qPCR analysis in the bark of Populus yunnanensis cuttings

Aim: The aim of this paper was to select and evaluate the stability of seven candidate reference genes (PD-E1, TUA2, UBQ, ACT2, TUB, 1-0Sand 18S RNA) under three different conditions for RT-qPCR analysis. Methodology: Cuttings of Poputus yunnanensis were cultured in water by two ways, upright and inverted vertically. Different internode barks were collected as test materials from 0 day to 49 day, once in seven day. Upright samples (U) and inverted samples (I) are two different conditions, total samples (U + I) means the third condition. Seven candidate reference genes (PO-El, TUA2, UBQ, ACT2, TUB, HIS and 185 RNA) were amplified by RT-qPCR. geNorm, NormFinder, BestKeeper and RankAggreg programs were used to select and evaluate the stability of seven candidate reference genes under three different conditions. Results: The final combination of multiple reference genes to normalize gene expression under different conditions were HIS + PO-El + TUB in upright samples (U), PO-El + TUA2 in inverted samples (I), PO-El + HIS + TUA2 in total samples (U + l). Interpretation: Stable reference genes could ensure RT-qPCR results correct by. The results provide an important reference gene selection guide in barks of P.yunnanensis cuttings for genes expression research.