Transport and Metabolism of Indol-3yl-(Acetic Acid-2-14C) in Pea Roots

Abstract

14C from indol-3-yl-(acetic acid-2-14C) (IAA-14C) was transported in a weak but definitely polar manner through segments of young and matured regions of pea roots. Greater quantities of 14C-labelled material moved acropetally than basipetally. Up to 70 per cent of radioactivity originally present in donor agar blocks was taken up by the root segments, but only approximately 2 to 3 per cent of this emerged into the receiver agar blocks. Any differences in uptake, transport, or binding of auxin were very slight in the three regions of root studied. The IAA-14C was metabolized during passage through the root segments, yielding two principal radioactive products. The identities of these were not determined, but they appeared to have auxin activity and may be formed spontaneously, but more slowly, in solutions of IAA-14C. IAA-14C was transported into receiver blocks more readily than its radioactive derivatives.