|Lyssenko, Nicholas -|
Submitted to: BARC Poster Day
Publication Type: Abstract Only
Publication Acceptance Date: February 22, 2000
Publication Date: N/A
Technical Abstract: Abscission involves controlled degradation of cell wall material and cell separation in the distinct group of plant cells that comprise the area of organ detachment or abscission zone (AZ). The phytohormones ethylene and auxin are known to be important temporal regulators of abscission. Moreover, the process is accompanied by an increase in the activity of several cell wall hydrolases including polygalacturonase and beta-1,4-glucanase (cellulase). Currently, information regarding the regulation of the genes encoding these enzymes in abscission is limited, thus the 5' upstream sequence of a bean abscission cellulase (BAC) is the focus of our present study. Comparison 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 BAC 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.