Acropetal movement of auxin: dependence on temperature.

The amounts of radioactive indole-3-acetic acid that moved, both basipetally and acropetally, through short sections of bean epicotyl were measured at 15 degrees and 25 degrees C in the presence and absence of 2,3,5-triiodobenzoic acid. Low temperature and this second compound each inhibited acropetal efflux of indole 3-acetic acid more than they did the influx. Results are interpreted as supporting a metabolically dependent component of the acropetal movement of auxin in bean epicotyls.