Figure 4. Relative expression levels of HpHYP1 in (R) root, (S) stem, (L) leaf, and (F) flower used for normalization using the most stable reference genes or a combination and the least stable genes.

Error bars indicate the mean standard error calculated from three biological replicates. The statistical level was according to ^∗P < 0.05, ^∗∗P < 0.01, and ^∗∗∗P < 0.001.