INTRACELLULAR LOCALIZATION OF NATIVE AUXIN IN AVENA COLEOPTILE

Intracellular localization of the native auxin in the Avenacole-optile tip was investigated by separating cellular fractionsby differential centrifugation. Each fraction was extractedwith ether and the auxin activity was measured by the sensitizedAvena curvature test. After the removal of the native free auxin,each fraction was alkaline-hydrolyied, and from these hydrolyzatesthe bound auxin was extracted with ether and its activity wasmeasured. Both the native free auxin and the native bound auxinin these extracts were identified as IAA by paper chromatography.The results show that the native free auxin occurs only in thesupernatant soluble cytoplasm, and that the native bound auxinlocalizes also in the supernatant. The distribution of the externallyapplied IAA was also investigated. (Received February 27, 1962; )