The transport of 3H and 14C in phloem strands of Heracleum lanatum and polyester threads

Abstract

Experiments are described which show a great similarity in the profiles of rapid movement of tritium after external application of 3H2O to a small segment of a phloem strand of Heracleum lanatum and a water-soaked polyester thread. Efflux of rapidly transported tritium from phloem strands and polyester threads was also similar. No rapid movement of radioisotope from [U-14C]sucrose, [6,6′-3H]sucrose, or [6-3H]glucose along phloem strands was observed. A possible explanation for the rapid movement of tritium in terms of proton transfer is offered. It is concluded that the rapid movement of tritium in a phloem strand which occurs when 3H2O is applied externally to a segment is an artifact and that no normal translocation is occurring.