Light and the transport and metabolism of indoleacetic acid in normal and albino dwarf pea seedlings

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Abstract
The patterns of transport and metabolism of IAA-2-14C applied to the apices of intact normal and albino dwarf pea seedlings were essentially similar under given light conditions. Light greatly reduced the decarboxylation of the applied IAA and stimulated the synthesis of indoleaspartic acid (IAAsp) in both normal and albino plants. In light considerably more 14C was exported from the apices of normal than albino plants; this result was attributed to the reduced capacity of the transport system in the latter. The specific activity of 14C in the stem decreased logarithmically with increasing distance from the treated apex. Light increased the steepness of the logarithmic profile. These results are discussed in relation to the rate of immobilization of IAA along the transport pathway by conversion to IAAsp. No evidence was found to support a previous suggestion (Pilet and Phipps, 1968) that IAA-oxidase activity and chlorophyll levels were causally linked.