The histone acetyltransferase GCN5 affects the inflorescence meristem and stamen development in Arabidopsis
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A central question in biology is to understand how gene expression is precisely regulated to give rise to a variety of forms during the process of development. Epigenetic effects such as DNA methylation or histone modification have been increasingly shown to play a critical role in regulation of genome function. GCN5 is a prototypical histone acetyltransferase that participates in regulating developmental gene expression in several metazoan species. In Arabidopsis thaliana, plants with T-DNA insertions in GCN5 (also known as HAG1) display a variety of pleiotropic effects including dwarfism, loss of apical dominance, and floral defects affecting fertility. We sought to determine when during early development floral abnormalities first arise. Using scanning electron microscopy, we demonstrate that gcn5-1/hag1-1 and gcn5-5/hag1-5 mutants display overproliferation of young buds and development of abnormal structures around the inflorescence meristem. gcn5 mutants also display defects in stamen number and arrangement at later stages. This analysis provides temporal and spatial information to aid in the identification of GCN5 target genes in the developing flower. Preliminary studies of putative targets using reverse transcriptase PCR suggest that the floral meristem identity gene LEAFY is among factors upregulated in gcn5-1 mutants.
KeywordsFlower development Arabidopsis thaliana Chromatin modification Histone acetyltransferase GCN5
Scanning electron microscopy
We thank the Arabidopsis Knockout Facility at the University of Wisconsin for making available the initial T-DNA mutant populations and the Salk Institute Genomic Analysis Laboratory for providing the sequence-indexed Arabidopsis T-DNA insertion mutants. We also thank Dr. Steven Triezenberg (Van Andel Research Institute) and members of the Hark laboratory (Muhlenberg College, MC) for helpful comments on the manuscript. We acknowledge John Santa Maria (MC) for his work in initiating this project and Zachary Kuschner (MC) for his assistance in genotyping gcn5 plants. This research was supported by Muhlenberg College, by a directed grant from the US Department of Education Award #P116Z040266, and by a Greek General Secretariat for Research and Technology grant #82337 to KV.
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