Abstract
CDKF;1 is a plant-specific cyclin-dependent kinase (CDK) and functions as a CDK-activating kinase (CAK) in vitro. Such a function has been previously examined with transiently expressed CDKF;1 in root protoplasts. To reveal its in vivo functions, we isolated a T-DNA insertion mutant and investigated the phenotype. The cdkf;1 mutant exhibited a dwarf phenotype and delayed growth. Root growth stopped around 7 days after germination and the expression of CYCB1-GUS almost disappeared, suggesting that CDKF;1 is required for cell division in the root meristem. We also found that the leaf blade area, cell number and cell size were smaller than those of wild-type plants. Moreover, the cdkf;1 mutant showed a lower level of DNA ploidy. On the other hand, cell division pattern during embryogenesis has not been defected in the mutant. Based on these results, we concluded that CDKF;1 plays an essential role in cell divisions during post-embryonic development.
