Fig. 3.

Time course of the effect of SNP on mRNA level of nitrate reductase in roots of tomato. The seedlings were fed with 0·5 mm (A) and 5 mm nitrate (B) for 2 weeks, and were then transferred to the nutrient solution without or with 5 µm SNP under continuous light conditions. The mRNA level of nitrate reductase was analysed at 0, 3, 6, 12 and 24 h after treatment. Relative mRNA levels were calculated and normalized with respect to α-tubulin mRNA (= 100 REU). Error bars represent the s.d (n = 6); no significant differences from the control were observed.