Movement of14C- and11C-labelled Assimilate in Wheat Leaves: the Effect of IAA

Abstract

The rate of translocation of naturally-loaded, radiolabelled assimilate has been studied in leaves of wheat treated with IAA. The velocity was measured directly by following the movement of ¹¹C-labelled material along the leaf. The kinetics of translocation were also estimated by using a two-compartment model to calculate the rate constant of disappearance of ¹⁴C from the fed area. IAA was applied at three different sites on the leaf and at various times up to 24 h before ¹⁴CO₂ feeding. No effects of IAA were observed on: (1) direction and velocity of transport; (2) loading of assimilate into the phloem; or (3) the site and kinetics of unloading. These results are discussed with reference to the movement of IAA along the transport path and the use of different tissues as experimental systems.