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Abstract Detail


Photomorphogenesis

Paddock, Troy [1], Armstrong, Greg [2].

Arabidopsis light-independent protochlorophyllide oxidoreductase A (PORA) restores bulk chlorophyll synthesis to a porB porC double mutant.

In angiosperms the strictly light-dependent reduction of protochlorophyllide (Pchlide) to chlorophyllide is catalyzed by NADPH:Pchlide oxidoreductase (POR). The Arabidopsis thaliana genome encodes three structurally related but differentially regulated POR genes PORA, PORB and PORC. PORA and PORB are coexpressed strongly early in development: during etiolation, germination and greening at the seedling cotyledon stage. PORB and PORC are coexpressed both during seedling development and throughout the later life of the plant, and therefore are responsible for post-cotyledon bulk chlorophyll synthesis. The Arabidopsis porB-1 porC-1 double mutant displays a xantha phenotype, and has both reduced amounts of prolamellar bodies and thylakoid membrane stacking in its plastids. Constitutive overexpression of PORA in the double mutant background produces slightly larger prolamellar bodies in etioplasts. Furthermore, bulk chlorophyll synthesis and thylakoid stacking are restored in the light-grown PORA-overexpressing porB porC double mutant. Chlorophyll production during seedling greening after prior etiolation is also restored to normal levels in the PORA-rescued plants. An Arabidopsis porB porC double mutant can therefore be functionally rescued by the addition of the overexpression of PORA, indicating that PORA alone is sufficient to support bulk chlorophyll synthesis throughout the life cycle in the absence of PORB and PORC.


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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

Keywords:
POR
greening
Chloroplast
etioplast.

Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P31010
Abstract ID:933


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