Submitted to: BARC Poster Day
Publication Type: Abstract Only
Publication Acceptance Date: March 29, 1999
Publication Date: N/A
Technical Abstract: In plants, the process of abscission is characterized by localized cell separation and cell wall degradation in the area of organ detachment, known as the abscission zone. Associated with this precise and coordinated developmental event, which is initiated by ethylene, is an increase in the activity of numerous cell wall hydrolases including polygalacturonase and beta-1,4-glucanase (cellulase). Previous work in this laboratory resulted in the isolation of several genes coding for cell wall-degrading enzymes from bean (Phaseolus vulgaris), soybean (Glycine max) and tomato (Lycopersicon esculentum). The 5' upstream sequence of one of these genes, an abscission-related cellulase, is the focus of our present study. Analysis of the abscission cellulase gene promoter of bean and soybean revealed regions of high sequence similarity. One region in particular comprised a core basic leucine zipper (bZIP) transcription factor-binding site (ACGT). Following mutation of this core sequence, an 80% decrease in expression of a luciferase reporter gene was observed in transient assays, when compared to luciferase expression resulting from the unmutated control. Using this core bZIP-binding site as a target, we are currently embarking on a yeast one-hybrid screen of a bean abscission zone expression library in order to identify putative regulators of abscission cellulase gene transcription. An understanding of how abscission-related genes are regulated will provide potential areas for gene manipulation, with a view to controlling abscission processes in crop plants.