Benzyladenine promotes early activation of p34cdc2-like kinase(s) during maize germination

The cell cycle is regulated, at least partially, by protein phosphorylation, activity that is carried out by a series of calcium-independent protein kinases among which the p34(cdc2) kinase plays a preponderant role. The behaviour of p34(cdc2)-like protein kinase(s) has been followed during germination of maize in the presence or absence of the synthetic cytokinin benzyladenine (BA). Whereas there is an increase in p34(cdc2)-like kinase(s) activity at 15h of germination in the presence of BA, coinciding with a peak of Ca2+-independent kinase activity, the amount of either the transcript for p34(cdc2) Or of the corresponding protein(s) does not show much variation during the 0-24 h period of germination studied, whether the phytohormone is present or not. Benzyladenine stimulates the cell cycle and promotes an early mitosis during maize germination. We have found evidence that BA promotes the movement of the p34(cdc2)-like protein(s) to nuclei several hours before this takes place during germination of control seeds, and this may constitute part of the mechanism by which the phytohormone promotes cytokinesis in plants.