Poster: Late and Moved Abstracts

Abs # 955: Characterization of a Plant Gene Suppressed by Infection of Cronartium quercuum f. sp. fusiforme

Presenter:	Long, Terri A, tlong@uga.edu
Authors	Long, Terri A (A)   Covert, Sarah F (B)
Affiliations:	(A): University of Georgia, Department of Genetics (B): University of Georgia, Warnell School of Forest Resources

Infection of loblolly pine by the biotrophic pathogen, Cronartium quercuum f. sp. fusiforme, causes spindle-shaped galls to form due to swelling, distortion and accumulation of the cells that make up woody tissue. Using differential display and suppression subtraction hybridization our lab previously identified several pine cDNAs that are suppressed in galled tissue. One of these, PT55, is homologous to ESTs collected from a wide variety of plant species as well as a gene in Arabidopsis thaliana involved in photosynthesis. The objective of this project is to further characterize how PT55 and the A. thaliana PT55 ortholog (AT55) are involved in stress response, and how changes in gene expression affect plant growth and development. Plants containing an AT55 promoter-GUS fusion indicate that AT55 is expressed in young leaves, phloem, selected reproductive tissues, and in response to wounding. This pattern correlates well with the expression of its apparent ortholog in loblolly pine according to northern analyses. Constitutive overexpression of AT55 or PT55 in A. thaliana produces discolored seedlings. As the plant ages the leaves turn greener, but are dimpled and smaller than wildtype leaves. RNAi-mediated suppression of AT55 causes leaf discoloration when plants are grown under certain conditions. Implications for the role of AT55 in stress response and development based on these and other results are discussed.