Auxin Transport in Tendril Segments of Passiflora caerulea

The movement of auxin through tendril segments of Passiflora caerulca L. has been investigated using IAA‐2‐14C. It has been shown that (1) flux of IAA through the segments is strongly polarized basipetally: (2) the amount of 14C recovered in the basal receiver blocks increases linearly within a transport period of 6 h; (3) velocity of basipetal transport is 14.5 mm h−1; (4) at least 70% of the radioactivity in the receiver blocks is confined to the IAA molecule: approximately 55% of 14C from methanolic extracts of the segments is IAA: (5) at low temperatures (2–4°C) the basipetal transport is abolished; (6) white light promotes basipetal transport, and this effect is abolished in a CO2‐free atmosphere; (7) no difference could be detected in 14C content between dorsal and ventral halves of tendril segments nor among individual dorsal and ventral receiver blocks.