Physiological Studies on the Outgrowth of the Epicotyl in Stizolobium hassjoo II. Its IAA Metabolim with Special Reference to the Activity in IAA Destruction

In this report, the outgrowth whose characteristics have already been described is examined for its IAA metabolism with special reference to its IAA destructive activity.1) The outgrowth formation from the cut surface of the epicotyl was remarkably accelerated by the application of IAA. This was observed not only in the lower parts of epicotyl, but also in the growing area which did not develop any outgrowth when subjected only to cutting. It is suggested that a relatively large amount of IAA may accumulate in the cut region and take a part in the formation of the outgrowth.2) The outgrowth was found to possess a considerably high amount of IAA as compared with non-outgrowth epicotyl.3) The maintenance by the outgrowth of such a high level of IAA may be, in part, attributed to the decreased rate of its in vivo IAA destruction. The authors express their thanks to Dr. Hiroh Shibaoka, Botanical Garden of University of Tokyo, for his kind help in IAA analysis.