Abstract
We have elucidated that the components of MAPK cascade were essential for cytokinesis of plant cell. The NPK1(MAPKKK) binds NACK1(kinesin-like protein ) and is activated during late M phase in tobacco. The NQK1(MAPKK) and NRK1(MAPK) were identified as the downstream components of NPK1. Over expressinon of these, which were dominant-negative form, inhibit the growth of cell plate and result in multinucleate cells with incomplete cell plates. But, the direct evidence, which NRK1 is involved in cytokinesis, has not come. In the present study, we elucidated that AtMPK4 was involved in cytokinesis in Arabidopsis. The ANQ1, which is the homolog of NQK1, activated AtMPK4 specifically in vitro. The avtivity of AtMPK4 was reduced in the anq1mutant . Furthermore, it was observed that multinucleate cells with incomplete cell plates in the root and the leaf in the atmpk4 mutant. These results suggest that MPK4 regulates the growth of cell plate positively.
