FUNCTIONAL ANALYSIS OF REGULATORY SEQUENCES AND ISOLATION OF PROTEIN FACTORS CONTROLING EXPRESSION OF AN ABSCISSION-SPECIFIC CELLULASE GENE FROM BEAN (PHASEOLUS VULGARIS).

Authors: Whitelaw, Catherine; LYSSENKO, NICHOLAS; Thai, Vanessa; Tucker, Mark

Submitted to: American Society of Plant Physiologists Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 7/21/2001
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: The bean abscission cellulase (BAC) gene is one of a number of genes induced coordinately with ethylene-promoted leaf abscission. Additionally, BAC gene expression is subject to complete repression by auxin. To investigate the molecular basis for ethylene and auxin regulation, we have examined the BAC promoter to identify cis-elements and trans-acting factors that are involved in BAC gene expression. Using deletion analysis and site-directed mutagenesis, we have characterized cis-acting regulatory elements in the BAC promoter involved in ethylene-induction and auxin-repression. A 10 bp mutation at -103 to -113 (with respect to the start of transcription) was sufficient to reduce reporter gene expression by 60%. Two different classes of transcription factor that bind this region of the BAC promoter were isolated by screening a one-hybrid library of bean leaf abscission zone cDNA in yeast. One class encode proteins of the NAC domain family, a novel class of plant transcription factors, while the other encode proteins belonging to the homeodomain leucine zipper family of DNA-binding proteins. Here we describe the identification and characterization of cis-elements and trans-acting factors from bean and discuss the implications of our results with respect to the regulation of abscission.