Figure 1.

Kinetin dose response of wild-type and cin5 mutant seedlings. Approximately 15 seeds were sown in a 22-ml gas chromatography vial containing 3 ml of MS medium supplemented with the indicated concentration of kinetin, incubated at 4°C for 4 days, flushed with hydrocarbon-free air, and sealed. Accumulated ethylene was measured after 72 h of incubation in the dark at 23°C. The means ± the SD based on three replicates are plotted. Very similar dose-response curves were obtained with the cytokinin benzyladenine (not shown). Note that the cin5 mutation only disrupts ethylene biosynthesis at lower concentrations of kinetin.