Fig. 7

The relative expression levels of MdSUVHs in response to drought and PEG treatment. The grafted ‘Golden delicious’ plotted plants were under drought treatment for 0, 2, 4, 6, and 8 days. For PEG treatment, ‘Golden delicious’ seedlings were under 20% PEG for 0, 2, 4, 6, and 8 h. Three biological replicates were performed for each treatment in the qRT-PCR analysis. The apple malate dehydrogenase gene (MdMDH) was used as the reference gene. All qRT-PCR data were calculated as relative units after normalization to the reference gene, which was the internal control. The expression levels of the non-PEG treatment were used to calibrate the relative expression levels. Statistically significant differences were assessed using SPSS software based on Tukey’s test at P < 0.05. Different letters among samples indicate significant differences in expression