The detection and estimation of the growth inhibitor xanthoxin in plants.

The plant growth inhibitor xanthoxin which can be prepared in vitro by the oxidation of certain xanthophylls has been identified in the ether extracts of the shoots of a wide variety of higher plants. Gas liquid chromatography of an acetylated derivative has been used for its quantitative estimation.Evidence is provided that xanthoxin is a true endogenous inhibitor and that violaxanthin or a related xanthophyll epoxide is its biogenetic precursor. The importance of xanthoxin and its relationship with abscisic acid and other plant growth inhibitors is discussed.