Distribution of indole‐3‐acetic acid in relation to the growth of etiolated Lupinus albus hypocotyls

The free indole‐3‐acetic acid (IAA) in methanolic extracts of etiolated hypocotyls of lupin ( Lupinus albus L., from Bari, Italy) was determined by fluorimetry. The distribution of IAA along the hypocotyls was parallel to the growth, but when growth ceased oscillations occurred in the auxin level. These oscillations could be related to processes of differentiation mediated by IAA. The oscillations did not obey any impulses from the apex, since the application of [1‐ 14 C]‐IAA to decapitated plants gives a distribution of radioactivity which also presents an undulatory pattern. Our results support the hypothesis that morphogenesis can be regulated by information transmitted by the translocation of waves of auxin.