Identification of Free Cytokinins and the Changes in Endogenous Levels during Tuber Development of Sweet Potato (Ipomoea batatas Lam.)

Trans-zeatin, trans-zeatin riboside and N⁶-(²-isopentenyl)adenosine(i⁶Ado) were found to be the major cytokinins by high performanceliquid chromatographic separation and gas chromatography-massspectrometric analysis in the small tubers of sweet potato (Ipomoeabatatas Lam. cv. Minamiyutaka) with a diameter of about 5 mm.During tuber development cytokinin levels were high in tubershaving a diameter below 12 mm, minimal in tubers with a diameterof 22.5 mm, and then gradually increased as the tuber developed. The role of cytokinins in tuber development of the sweet potatois discussed. (Received May 20, 1982; Accepted August 10, 1983)