Figure 4.

Expression analysis of AtVHA-d1 and AtVHA-d2 under multiple stresses. Ten-day-old Arabidopsis seedlings were treated with 150 mM NaCl, 300 mM mannitol, 5 mM H₂O₂, 100 µM ABA, 4 °C (cold), or 37 °C (heat) for 0, 3, 6, 12, and 24 h. The expression of AtVHA-d1 (A) and AtVHA-d2 (B) was investigated by qPCR. The AtActin2 gene was used as an internal control, and the transcript level in untreated seedlings was set as 1.0. Asterisks indicate a significant difference between untreated and stress-treated seedlings (* p < 0.05; ** p < 0.01; Student′s t-test). Error bars represent the SD (n = 3).