Figure 3.

In vivo deuterium labeling of ZMP (■) and iPMP (○) in transgenic A. thaliana plants, incubated on deuterium-enriched media containing dexamethasone to induce ipt expression. Enrichment is expressed as the ratio of deuterium labeled substance (tracer)/unlabeled substance (tracee), after correction for natural isotope distribution. Initiation of cytokinin overproduction is marked by an arrow. Standard deviation is indicated by error bars. The slope of the ZMP 6- to 12-h regression line was significantly higher than the slope of the 0- to 3-h data (P < 0.05, dummy variable analysis).