Figure 5.

Rice PDX1s do not respond to heat stress. A, Schematic representation of the catalytic PDX1s (cPDX1; OsPDX1.3a, OsPDX10.3b, and OsPDX10.3c) present in rice. The single exon in each case is depicted in black and fragments of the respective upstream and downstream regions in gray. The numbers depict distance in bp from the translational start site (+1). B, Quantitative analysis of OsPDX1.3a, OsPDX1.3b, OsPDX1.3c, and OsHSP101 expression in rice (cv Nipponbare). The fold-change is depicted relative to before heat stress (time 0, set to 1) and after 30-min and 60-min exposure to 45°C for 1 h. Four-day-old seedlings precultivated at 28°C under continuous light (100–150 μmol photons m⁻² s⁻¹) were used. Statistical significance was calculated from a pairwise comparison to time 0, indicated by an asterisk for P < 0.001. In all cases, error bars represent SE. C, Analysis of Arabidopsis HSFA1b binding to a promoter fragment of OsPDX1.3b by EMSA. A TAMRA-labeled double-stranded probe (promoter fragment −229 to −144; Supplemental Table S2) was incubated with (+) purified AtHSFA1b (3 μm) and increasing concentrations of the probe (50 [+], 100 [++], and 200 nm [+++], respectively). Reactions were resolved on 5% native polyacrylamide gels.