Auxin transport in roots : VIII. The distribution of radioactivity in the tissues of Zea root segments.

Experiments involving soluble-compound microautoradiography and girdling procedures have been carried out in an attempt to identify the tissues responsible for the acropetally polarised transport of indole-3-acetic acid through segments of Zea mays roots. The results strongly suggest that acropetal movement of IAA takes place in both the stele and the cortex, but with a much greater efficiency in the former tissue than in the latter. Basipetal movement of IAA is much less than acropetal movement and appears to take place with equel efficiency in the cortex and stele.