The expression profiles of HSFA6a and HSFA6b in response to HS, salt, osmotic, and ABA stress. A to D, Nine-day-old seedlings were treated with HS or incubated with water containing NaCl, mannitol, or ABA at different concentrations and times. The transcription levels of HSFA6a and HSFA6b were analyzed by RT-PCR. The pictogram shows the HS regime (right of A): 37°C sublethal HS for 1 h (HS) → 22°C recovery for 2 h (R) → 44°C lethal HS for 190 min (LHS). 22°C treatment was a control (CK). HSP18.1-CI, used as a reference, is an HS-responsive marker gene. ACTIN2 (ACT2) was used as a loading control.