Cell to Cell and Long distance Signaling
Gagne, Jennifer M. , Song, Sang-Kee , Clark, Steven E. .
The Protein Phosphatase Type 2C Proteins, POL and PLL1 are Required for Multiple Asymmetric Cell Divisions During Plant Development.
Precise regulation of the stem cell populations in the meristems is vital for proper plant development. The CLAVATA (CLV) pathway plays a key role in controlling meristem size by modulating the mRNA levels of the homeodomain transcription factor, WUSCHEL (WUS). WUS promotes stem cell specification and the CLV pathway negatively regulates WUS expression. Two CLV pathway components, the protein phosphatase type 2C proteins POLTERGEIST (POL) and PLL1, are functionally overlapping positive regulators of WUS expression. Genetic studies have shown that POL and PLL1 act downstream of and are negatively regulated by the other known CLV pathway components. Detailed analysis of pol pll1 double mutants has revealed that the mutant embryos fail to properly specify their basal halves. This defect appears to be due to the loss of key asymmetric cell divisions early in development. WUS and the other CLV pathway components are not required for these processes revealing that POL and PLL1 are shared signaling components for multiple developmental pathways. Interestingly, WUS expression is also known to be regulated by asymmetric cell divisions. Specifically, the apical daughters of L3 stem cells remain stem cells while the basal daughters differentiate and express WUS. It appears then that POL and PLL1 may be required for each of these pathways to set up asymmetric cell division. To further understand the mechanisms of POL and PLL1 signaling we have performed localization studies in yeast, BY2 cells and Arabidopsis. These studies have revealed that POL and PLL1 are predominantly localized to the plasma membrane. Based on these findings, our current model is that POL and PLL1 are key for specific asymmetric cell divisions during plant development.
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1 - University of Michigan, Department of Molecular, Cellular and Developmental Biology, 830 N. University Ave, Ann Arbor, MI, 48109-1048, USA
2 - University of Michigan, Department of Molecular, Cellular and Developmental Biology
Presentation Type: ASPB Minisymposium
Location: Continental C/Hilton
Date: Sunday, July 8th, 2007
Time: 2:00 PM