Cytoskeleton Structure and Dynamics
Burgos-Rivera, Brunilis , Ruzicka, Daniel, R. , McKinney, Elizabeth, C. , Meagher, Richard, B. .
Arabidopsis Actin Depolymerizing Factor ADF9 Participates in Both Cytoplasmic and Nuclear Processes.
ADFs modulate rates of actin polymerization and depolymerization by severing actin filaments and enhancing actin filament turnover. Higher plant genomes contain at least four ancient classes of ADF genes. This study examines one member of the ADF family in Arabidopsis, ADF9. Although microarray gene expression data is available for ADF9, little is known about the functions of the protein encoded by this gene. ADF9 promoter-GUS reporter fusions showed that ADF9 was constitutively expressed, with the highest levels in fast expanding tissues such as the apical meristem, root tip, and callus. Expression of the GUS reporter gene was greatly increased in the root tip meristem, trichomes, and shoot apical meristem in response to various hormonal treatments. To gain insight into possible gene functions, we analyzed two ADF9 T-DNA insertion mutants. The knockout and knockdown mutants, adf9-1 and adf9-2, had a 99-fold and 2-fold reduction in transcript levels, respectively. Compared to wild type, the mutant plants were smaller in size, flowered early, and had an increased number of primary inflorescences and longer branches. An ADF9 expression clone complemented all the adf9-1 mutant phenotypes. In addition, we found that FLOWERING LOCUS C (FLC), a master regulator of the transition to flowering is repressed 20-fold in adf9-1. The downstream targets of FLC, LEAFY (LFY) and APETALA 1 (AP1) are upregulated 22- and 4-fold respectively in adf9-1, as expected. These results suggest that ADF9 regulates both nuclear and cytoplasmically controlled growth processes.
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1 - The University of Georgia, Genetics, Life Sciences Building B422, Athens, GA, 30602, USA
2 - The University of Georgia, Genetics
actin depolymerizing factor
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM