Abstract
Nuclei alter their shapes during developmental processes of plant cells. The nuclear-shape changes probably affect nuclear functions and high-order functions of cells, tissues, organs and individuals, and the mechanisms have mostly remained unclear. To reveal the molecular mechanisms, we have isolated several lines of Arabidopsis mutants that have aberrant nuclear shapes. Although nuclei of epidermal cells in Arabidopsis thaliana usually show elongated shape, some mutants had spherical shaped nuclei and another one had larger non-spherical shaped nuclei than wild-type plants. Map-based cloning identified responsible genes for two mutants, both of which had spherical and smaller nuclei. kaku2 had a base substitution in the LINC1 gene that encodes a coiled-coil protein localized at nuclear periphery for regulating nuclear morphology. kaku4 had a base substitution in the gene that encodes an unknown protein. Transient expression assay indicated that GFP-tagged KAKU4 was localized at nuclear envelope. Overexpression of KAKU4 caused elongation of nuclei in tobacco cells. Our findings suggest that KAKU2 and KAKU4 are involved in nuclear organization in plant cells.
