WEE1 regulates the cell cycle by inactivating cyclin dependent protein kinases (CDKs) via phosphorylation. In yeast and animal cells, CDC25 phosphatase dephosphorylates the CDK releasing cells into mitosis, but in plants, its role is less clear. Expression of fission yeast CDC25 (Spcdc25) in tobacco results in small cell size, premature flowering and increased shoot morphogenetic capacity in culture. When Arath;WEE1 is over-expressed in Arabidopsis, root apical meristem cell size increases, and morphogenetic capacity of cultured hypocotyls is reduced. However expression of Arath;WEE1 in tobacco plants resulted in precocious flowering and increased shoot morphogenesis of stem explants, and in BY2 cultures cell size was reduced. This phenotype is similar to expression of Spcdc25 and is consistent with a dominant negative effect on WEE1 action. Consistent with this putative mechanism, WEE1 protein levels fell and CDKB levels rose prematurely, coinciding with early mitosis. The phenotype is not due to sense-mediated silencing of WEE1, as overall levels of WEE1 transcript were not reduced in BY2 lines expressing Arath;WEE1. However the pattern of native WEE1 transcript accumulation through the cell cycle was altered by Arath;WEE1 expression, suggesting feedback inhibition of native WEE1 transcription.

• MeSH
• Plants, Genetically Modified MeSH
• Plant Roots genetics   metabolism   MeSH
• Cells, Cultured MeSH
• Flowers genetics   metabolism   MeSH
• Plant Leaves genetics   metabolism   MeSH
• Mitosis genetics   MeSH
• Protein Serine-Threonine Kinases genetics   metabolism   MeSH
• Arabidopsis Proteins genetics   metabolism   MeSH
• Gene Expression Regulation, Plant MeSH
• Plant Stems genetics   metabolism   MeSH
• Nicotiana cytology   genetics   metabolism   MeSH
• Cell Size MeSH
• Plant Shoots genetics   metabolism   MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Protein Serine-Threonine Kinases MeSH
• Arabidopsis Proteins MeSH
• WEE1 protein, Arabidopsis MeSH Browser