Auxin transport in leafy pea stem cuttings is partially driven by photosynthesis

When /sup 14/C-IAA was applied to the apex of disbudded leafy pea stem cuttings (15 cm long), the movement of /sup 14/C-IAA to the base of the cuttings after 24 h was influenced by the photosynthetic rate. In the absence of photosynthesis, light did not influence /sup 14/C-IAA movement. Photosynthesis was altered by varying light, CO/sub 2/ concentration, or stomatal aperature (blocked with an antitranspirant). Radioactivity (identified by co-chromatography) was 25, 60, and 5% IAA, IAA-aspartate, and indolealdehyde respectively regardless of treatment. Adventitious root formation was reduced 50 to 95% and movement of IAA was inhibited 50 to 70% by decreasing gross photosynthesis 90 to 100%. Apparently, photosynthesis partially drives the movement of IAA from the apex to the base where roots arise. This gives a probably role of photosynthesis in rooting, because in this system virtually no rooting will take place without exogenous auxin and at least a low level of gross photosynthesis.