| Abstract Detail
Growth and Vegetative Development Wu, Shuang [1], Scheible, Wolf-Rüdiger [2], Baskin, Tobias [3]. Temperature-sensitive allele of RSW4 links the putative plant separase to cell division and cell expansion in the root of Arabidopsis. The temperature-sensitive mutant, radially swollen4 (rsw4), was isolated previously as root morphogenesis mutant, in which expansion becomes less anisotropic. Map-based cloning revealed that a point mutation occurs in At4g22970. This gene encodes a homologue of separase, an essential protein in eukaryotes involved in separating replicated chromatids at the onset of anaphase. RSW4 is the single copy of separase in arabidopsis and T-DNA insertion alleles are lethal. The connection between reduced separase function and root swelling remains unclear. Here I report the confirmation of mitotic defects from reduced separase function by means of immuno-fluorescence staining, TEM, and observations of histone-GFP in living cells. The transition from metaphase to anaphase in the mutant at the restrictive temperature(30ËšC) is severely affected. Chromosome bridges and un-separated sister chromatids are common in the mutant. Although affected cells proceed into cytokinesis, new cell walls are often incomplete, characterized by cell wall stubs and gapped cell walls. With longer time at 30ËšC, the meristem area of the mutant decreases, corresponding to a decreased rate of cell production. To explain root swelling in rsw4, we first quantified the angular distribution of cortical microtubules in root epidermal cells, imaged with immuno-fluorescence and in living cells expressing GFP-tubulin. Cortical microtubules become disorganized and the extent of the disorganization correlates with the time course of root swelling. This suggests that separase could act at interphase on microtubule behavior. However, we also found that with time at 30ËšC, cyclinB-GUS staining is enhanced in the mutant suggesting the cell cycle prograssion is impaired. To explore the regulatory state of cells in rsw4 further, we have initiated a large analysis of mRNA using micro-array and real time PCR methods. Our hypothesis is that orderly progression through M-phase plays an essential role in the determination of cell and organ polarity.
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1 - University of Massachusetts, Amherst, Biology Department, Morrill III South, 611 North Pleasant St, Univeristy of Massachusetts, amherst, MA, 01002, USA
2 - Max-Planck-Institute for Molecular Plant Physiology, Metabolic Networks
3 - University of Massachusetts, Amherst, Biology Department
Keywords:
separase
cell division
cell expansion
root growth
microtubule.
Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P26039
Abstract ID:1200 |
