LEAF ABSCISSION IN COLEUS II. THE DISTRIBUTION AND FATE OF [14C]-INDOLYLACETIC ACID IN THE PETIOLE.

Autoradiographs of sections of explants treated distally with [14C]indolylacetic acid (IAA) for 48 hours showed that radioactivity was higher in the abscission zone than in the neighbouring distal and proximal zones at all stages of its development. Higher activity in the abscission zone compared with the distal zone (about 4 to 1) was confirmed by liquid scintillation counting and scanning of paper chromatograms of extracts. The chromatograms also showed that a large part of the activity from abscission zones was due to unchanged IAA. This was confirmed by showing that a large part of the radioactivity in the abscission zone could be removed by treating the explants with unlabelled IAA. [ABSTRACT FROM AUTHOR]