This proposal concerns molecular events involved in light responses of the ferredoxin gene Fed 1. These responses are quite different from those of other well-studied light regulated genes with respect to the speed and reversibility of light effects. We have recently shown that cis-acting elements responsible are located within the transcribed portion of the gene. This arrangement is unprecedented in plant systems and strongly suggests that post-transcriptional events affecting Fed 1 mRNA stability has not yet received much attention in plant systems, and the Fed 1 gene offers an opportunity to develop a major model system. The first major objective of the present proposal is to further define the relative importance of transcriptional and post-transcriptional events at different stages of plant development. Transcription and mRNa degradation rates will be measured in transgenic plants (or plant cells) carrying various chimeric Fed 1 genes. Both green plants and etiolated seedings will be examined, since diurnal modulation of Fed 1 mRNA levels in mature leaves may occur by a different mechanism than the first induction of gene expression in seedlings. The second objective is to further define the cis-acting sequences required for light effects on Fed 1 mRNA accumulation. As noted above, these sequences are located within the single Fed 1 exon. Effective element(s) will be defined using in vitro mutagenesis in combination with functional assays ranging from transgenic plants to protoplast electroporation with synthetic mRNA. Elements conferring light responses in green leaves or cultured cells will also be compared to those involved in the induction of Fed 1 in dark-grown seedlings. Finally, defined light regulatory elements will be used to begin studies on the biochemical basis of the light response and on factors which may participate in specific interactions with Fed 1 mRNA.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM043108-03
Application #
3302044
Study Section
Molecular Cytology Study Section (CTY)
Project Start
1989-12-01
Project End
1994-11-30
Budget Start
1991-12-01
Budget End
1992-11-30
Support Year
3
Fiscal Year
1992
Total Cost
Indirect Cost
Name
North Carolina State University Raleigh
Department
Type
Schools of Earth Sciences/Natur
DUNS #
City
Raleigh
State
NC
Country
United States
Zip Code
27695
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Petracek, M E; Nuygen, T; Thompson, W F et al. (2000) Premature termination codons destabilize ferredoxin-1 mRNA when ferredoxin-1 is translated. Plant J 21:563-9
Petracek, M E; Dickey, L F; Nguyen, T T et al. (1998) Ferredoxin-1 mRNA is destabilized by changes in photosynthetic electron transport. Proc Natl Acad Sci U S A 95:9009-13
Dickey, L F; Petracek, M E; Nguyen, T T et al. (1998) Light regulation of Fed-1 mRNA requires an element in the 5' untranslated region and correlates with differential polyribosome association. Plant Cell 10:475-84
Petracek, M E; Dickey, L F; Huber, S C et al. (1997) Light-regulated changes in abundance and polyribosome association of ferredoxin mRNA are dependent on photosynthesis. Plant Cell 9:2291-300
Dickey, L F; Nguyen, T T; Allen, G C et al. (1994) Light modulation of ferredoxin mRNA abundance requires an open reading frame. Plant Cell 6:1171-6
Frances, S; White, M J; Edgerton, M D et al. (1992) Initial characterization of a pea mutant with light-independent photomorphogenesis. Plant Cell 4:1519-30
Gallo-Meagher, M; Sowinski, D A; Elliott, R C et al. (1992) Both internal and external regulatory elements control expression of the pea Fed-1 gene in transgenic tobacco seedlings. Plant Cell 4:389-95
Gallo-Meagher, M; Sowinski, D A; Thompson, W F (1992) The pea ferredoxin I gene exhibits different light responses in pea and tobacco. Plant Cell 4:383-8
Dickey, L F; Gallo-Meagher, M; Thompson, W F (1992) Light regulatory sequences are located within the 5' portion of the Fed-1 message sequence. EMBO J 11:2311-7

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