BACKGROUND: During the last three decades, the cell cycle and its control by cyclin-dependent kinases (CDKs) have been extensively studied in eukaryotes. This endeavour has produced an overall picture that basic mechanisms seem to be largely conserved among all eukaryotes. The intricate regulation of CDK activities includes, among others, CDK activation by @entity49494 phosphatase at G   /M. In plants, however, studies of this regulation have lagged behind as a plant @entity49494 homologue or other unrelated phosphatase active at G   /M have not yet been identified. SCOPE: Failure to identify a plant mitotic CDK activatory phosphatase led to characterization of the effects of alien @entity49494 gene expression in plants. @entity286 , expressing the @entity6739 mitotic activator gene, Spcdc25, exhibited morphological, developmental and biochemical changes when compared with @entity164 ( @entity164 ) and, importantly, increased CDK dephosphorylation at G   /M. Besides changes in leaf shape, internode length and root development, in day-neutral @entity286 there was dramatically earlier onset of flowering with a disturbed acropetal floral capacity gradient typical of @entity164 . In vitro, de novo organ formation revealed substantially earlier and more abundant formation of shoot primordia on Spcdc25 @entity286 stem segments grown on shoot-inducing media when compared with @entity164 . Moreover, in contrast to @entity164 , stem segments from transgenic plants formed shoots even without application of exogenous growth regulator. Spcdc25-expressing BY-2 cells exhibited a reduced mitotic cell size due to a shortening of the G    phase together with high activity of cyclin-dependent kinase, NtCDKB1, in early S-phase, S/G    and early M-phase. Spcdc25-expressing @entity286 (' @entity286 ') cell suspension cultures showed a clustered, more circular, cell phenotype compared with chains of elongated @entity164 cells, and increased content of starch and soluble @entity3363 . Taken together, Spcdc25 expression had cytokinin-like effects on the characteristics studied, although determination of endogenous cytokinin levels revealed a dramatic decrease in Spcdc25 transgenics. CONCLUSIONS: The data gained using the plants expressing @entity375 mitotic activator, Spcdc25, clearly argue for the existence and importance of activatory dephosphorylation at G   /M transition and its interaction with @entity19164 signalling in plants. The observed cytokinin-like effects of Spcdc25 expression are consistent with the concept of interaction between cell cycle regulators and phytohormones during plant development. The G   /M control of the plant cell cycle, however, remains an elusive issue as doubts persist about the mode of activatory dephosphorylation, which in other eukaryotes is provided by @entity49494 phosphatase serving as a final all-or-nothing mitosis regulator.

Regulatory dephosphorylation of CDK at G   /M in plants: @entity375 mitotic phosphatase XXXX induces cytokinin-like effects in transgenic @entity286 morphogenesis.

@entity286 :: ('4097', 'Species') :: ['Samsun', 'tobacco', 'Tobacco'] @entity49494 :: ('851019(Tax:4932)', 'Gene') :: ['CDC25', 'cdc25', 'Cdc25'] @entity6739 :: ('4896', 'Species') :: ['Schizosaccharomyces pombe'] @entity19164 :: ('CHEBI:23530', 'Chemical') :: ['cytokinin'] @entity164 :: ('MESH:D017827', 'Disease') :: ['WT', 'wild type'] @entity375 :: ('4932', 'Species') :: ['yeast'] @entity3363 :: ('MESH:D002241', 'Chemical') :: ['sugars']
@entity49494 :: (851019(Tax:4932),Gene) :: ['cdc25']
