Poster: Vegetative development

Abs # 334: Characterization of Expression and Function of the Guard Cell Associated 2 (GCA2) Gene from Arabidopsis thaliana

Presenter:	Yan, Dongqing , doyan@syr.edu
Authors	Yan, Dongqing  (A)   Moskal, William A., Jr. (A)   Smart, Lawrence B. (A)
Affiliations:	(A): SUNY College of Environmental Science and Forestry
Web Site:	http://www.esf.edu/efb/smart/

Guard cells are highly specialized cells that modulate the opening and closing of stomata, and thus control gas exchange between the plant and its environment. The goal of this project is to identify novel components regulating guard cell development and stomatal physiology based on guard-cell-specific expression. By screening enhancer trap tagged lines of Arabidopsis, we identified several guard-cell-associated lines. One of those, GCA2, displayed GUS expression in guard cells, especially in cotyledons or in wounded tissues. Additionally, a variable number of abnormal, horseshoe-shaped guard cells in the supposed location of normal stomata were observed in homozygous GCA2 plants. The tagged locus was isolated by a PCR-based genome walking technique, revealing that the GCA2 T-DNA insertion site was within the upstream sequence of a gene on chromosome 3 with homology to the sunflower SF16 gene. The deduced amino acid sequence of GCA2 includes calmodulin-binding and nuclear localization motifs. We have transformed Arabidopsis with a construct fusing GFP with the GCA2 coding region to determine its subcellular localization. We will characterize the expression of the GCA2 gene by northern analysis and in situ hybridization. Additional putative GCA2 knockout lines have been obtained from the Arabidopsis Biological Resource Center and will be compared with the original tagged GCA2 line.