Figure 2.

Time-dependent response of Arabidopsis seedlings to oxidative, salt and osmotic stress revealed through thiamine biosynthesis gene expression changes. Nine day old seedlings of A. thaliana ecotype Columbia were transferred onto MS medium supplemented with 0.2 μM paraquat (PQ), 200 mM NaCl or 200 mM sorbitol (SOR) for the indicated times. Transcripts of the THI1 (coding for HET-P synthase), THIC (coding for HMP-P synthase), TH1 (encoding thiamine monophosphate synthase/HMP-P kinase bifunctional enzyme) and TPK (coding for thiamine pyrophosphokinase) genes were quantified in seedling leaves by RT-PCR and expressed relative to the corresponding gene expression levels in the control seedlings grown under stress-free conditions. The asterisk indicates a statistically significant difference when compared with the control samples (t-test, P < 0.05).