THE KEULE GENE IS INVOLVED IN CYTOKINESIS IN ARABIDOPSIS

We present evidence to show that the KEULE gene of Arabidopsis is invo lved in cytokinesis. Mutant kettle embryos have large multinucleate ce lls with gapped or incomplete cross walls, as well as cell wall. stubs that are very similar to those observed upon caffeine inhibition of c ytokinesis in plants. These defects are observed in all populations of dividing cells in the mutant, including calli, but less frequently in mature cells. Cell division appears to be slowed down, and the planes of cell division are often misoriented. In late embryos and seedlings , cross-wall formation usually appears complete, suggesting that the r equirement for KEULE during cytokinesis is not absolute. Nonetheless, kettle mutants die as seedlings with large polyploid cells. The bloate d surface layer of kettle seedlings does not uniformly behave like wil d-type epidermis, and patches of this layer assume characteristics of the underlying ground tissue. The cytokinesis defect of kettle mutants may influence aspects of cellular differentiation.