Changes of cytokinin levels in tuberous roots of sweet potato during budding

摘要

Presence and levels of cytokinin in tuberous roots of sweet potato (Ipomoea bataatas Lam, cv. Kohkei No. 14) were determined at five different stages during budding by means of mass spectrometry using deuterium-labeled standards. New buds that were purplish red were observed on the tuberous roots 4 days after cultivation. 6-(-3-Methyl-2-butenylamino)-9-glucosylpurine (iPG) was maintained at high levels throughout the cultivation. The levels of trans-ribosylzeatin (RZ) increased until 4 days after cultivation. The rise of trans-RZ level appears to be accompanied by the decline in the levels of iPG. While trans-GZ was maintained at relatively high levels, no significant fluctuation of the level was observed during budding. Trans-Z, cis-GZ and iPA were at very low levels during budding. It seems therefore that iPG functions as a storage form of cytokinin in tuberous roots of sweet potato.