Barbieri, Rosario , Armstrong, Greg .
Etioplast and POR protein-associated changes in nuclear gene expression.
In addition to photosynthesis, plastids contribute to other crucial aspects of plant metabolism. In green tissues, nuclear gene expression is highly influenced by photosynthesis as part of a chloroplast-to-nucleus communication process that uses chlorophyll precursors and photosynthesis byproducts as signals. Despite the important roles of non-photosynthetic plastids in plant development, there is little evidence as to whether these plastid types influence nuclear gene expression.
We tested the hypothesis that plastids in dark-grown seedlings, the etioplasts, are able to communicate their metabolic status to the nucleus and promote changes in nuclear gene expression. The etioplastís main morphological feature is the prolamellar body membrane (PLB), a paracrystalline arrangement of lipids, proteins and pigments, which reorganizes into thylakoids at the onset of light-induced greening. NADPH:protochlorophyllide oxidoreductase (POR) is a strictly light-dependent enzyme responsible for the photoreduction of protochlorophyllide during chlorophyll biosynthesis. The abundance of the dark-accumulated PORA and PORB isoforms in etioplasts also directly affects the size of the PLBs and, therefore, the etioplast developmental status.
Thus, we used a microarray approach to compare the nuclear transcriptomes of etiolated knockout mutants (porA-1, porB-1, and porC-1) for the three Arabidopsis thaliana POR isoforms and of two POR overexpressors (PAO-3, PBO-10). We found that most of the changes in nuclear gene expression were specific to the porA-1 mutation, independent of the size of the PLB. We propose that the PORA protein has a specific role during seedling maturation in the dark that goes beyond its enzymatic function and differentiates it from the other POR isoforms.
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1 - The Ohio State Univesity, Plant Cellular and Molecular Biology, 500 Aronoff Laboratory, 318 West 12th Ave, Columbus, OH, 43210, USA
2 - The Ohio State Univesity, Plant Cellular and Molecular Biology
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM