Poster: Cell Cycle & Cytokinesis

Abs # 1091: SCD1 is required for stomatal cell cytokinesis and polarized cell expansion in Arabidopsis thaliana

Presenter:	Falbel, Tanya G., tgfalbel@biochem.wisc.edu
Authors	Falbel, Tanya G. (A)   Koch, Lisa M. (A)   Nadeau, Jeanette A. (B)   Sack, Fred D. (B)   Bednarek, Sebastian Y. (A)
Affiliations:	(A): University of Wisconsin-Madison Biochemistry (B): Ohio State University Plant Biology

In the leaf epidermis, guard mother cells undergo a symmetric division to form the guard cells of stomata. We have identified a temperature-sensitive Arabidopsis mutant, stomatal cytokinesis-defective 1-1 (scd1-1) which affects this specialized division. Defective scd1-1 guard cells are binucleate, forming incomplete cell walls. Cytokinesis is also disrupted in epidermal pavement cells. scd1-1 also affected seedling growth, root elongation and flower morphogenesis. More severe scd1 T-DNA insertion alleles, ( scd1-2 and scd1-3) markedly affect polar cell expansion, observable in root cells, as well as in trichomes and root hairs. SCD1 is a unique gene in Arabidopsis that encodes a protein related to animal proteins that interact with Rab GTPases involved in intracellular protein transport and/or mitogen-activated protein kinases. Immunofluorescence microscopy and analysis of a functional GFP-SCD1 fusion protein in wild type plants has shown that SCD1 was localized in a punctate pattern at or near the plasma membrane. In addition, subcellular fractionation studies have demonstrated that SCD1 is a Triton-insoluble peripheral membrane protein. Further characterization of the distribution and function of SCD1 in vesicle trafficking during plant cytokinesis and cell expansion will be presented.