Inhibition of cell division in a moss protonema by some cytokinin isomers.

The cytokinin isomers, 1- and 9-isopentenyladenine, are very active inhibitors of cell division in the protonema of the moss Ceratodon purpureus. They also abolish the N(6)-isopentenyladenine-induced stimulation of cell divisions in this material whereas they are inactive on the induction of gametophore buds in moss protonemata by cytokinins.