Figure 1.

Diurnal activation of the HsfB1 gene by BTH. Five-week-old Arabidopsis (accession Columbia-0) plants were grown on soil at 8 h of light/16 h of dark, 20°C, and 60% to 70% relative humidity. Plants were sprayed at 10 am (that is 2 h after start of the light period) with a formulation of BTH (100 µm) or with a blank formulation devoid of BTH (blank). At various times after treatment, RNA was extracted from sprayed leaves and assayed for the accumulation of HsfB1 transcripts by quantitative reverse transcription (qRT)-PCR using gene-specific primers (Supplemental Table S1) as described by Beckers et al. (2009). Relative amounts were normalized to those of ACTIN2. Bars represent means of two replicate measurements (n = 2). White and black bars below the x axis indicate whether the harvest of leaves was done in the light or the dark. The experiment was repeated two times with similar results.