A New Unidentified Indole Hormone in Maryland Mammoth Tobacco

Abstract

IT has been reported previously¹ that the short-day plant, Maryland Mammoth tobacco, will flower under long day-lengths (14½–15½ hr.) if exposed to varying dosages of γ-rays. Recently, we have been investigating the effect of γ-radiation on the endogenous level of the indole compounds occurring naturally in leaf, stem, root and apical tissues of γ-irradiated and normal Maryland Mammoth tobacco. Large quantities of these tissues (300–1,000 gm.) have been extracted with absolute ethanol, employing a technique for extraction and paper chromatography as described previously². Microlitre quantities of the extracts, after acidification and extraction with ethyl ether, were spotted on Whatman No. 1 filter paper and chromatographed in seventeen different solvents. Colours were developed with p-dimethylaminobenzaldehyde. 3-Indoleacetic acid was not detected in any of more than thirty-five individual extractions of leaf, stem, root or apical tissues of normal or γ-irradiated Maryland Mammoth tobacco. However, an unidentified indole compound was found in the leaf and apical extracts with R _F values as shown in Table 1.